CN101528962A - Cold work die steel, die, and method for production of cold work die steel - Google Patents
Cold work die steel, die, and method for production of cold work die steel Download PDFInfo
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- CN101528962A CN101528962A CNA200780038626XA CN200780038626A CN101528962A CN 101528962 A CN101528962 A CN 101528962A CN A200780038626X A CNA200780038626X A CN A200780038626XA CN 200780038626 A CN200780038626 A CN 200780038626A CN 101528962 A CN101528962 A CN 101528962A
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Abstract
Disclosed is a cold work die steel which comprises (by mass): C: 0.20-0.60%, Si: 0.5-2.00%, Mn: 0.1-2%, Cr: 3.00-9.00%, Al: 0.3-2.0%, Cu: 1.00-5%, Ni: 1.00-5%, Mo: 0.5-3% and/or W: 2% or less (including 0%), and S: 0.10% or less (excluding 0%) wherein these components satisfy the following requirements (1) to (3) [wherein each square bracket [ ] means a content (%) of each element]: (1) [Cr] x [C]=3.00; (2) [Cu]/[Ni]: 0.5-2.2; and (3) [Mo]+0.5 x [W]: 0.5-3.0%, with the remainder being iron and unavoidable impurities. Also disclosed is a die produced by using the steel. Further disclosed is a method for producing the cold work die steel.
Description
Technical field
The present invention relates to a kind of cold work die steel and mould, and relate to a kind of method that is used to make cold work die steel.Particularly, the present invention relates to can be used as at automotive sheet and the household electrical appliance mould die steel of material that uses in the cold/hot-press forging moulding (punching press, bending, drawing, finishing etc.) of steel plate, and relate to a kind of method that is used to make such die steel.
Background technology
Be used to form automotive sheet and household electrical appliance and be required to have life-span of prolongation, and the intensity of steel plate increases with the mould of steel plate.Particularly,, consider environmental problem, need tensile strength to be at least about the height tension steel plate of 590MPa more and more to improve speedometer for automobile (mileage) for automotive sheet; Therefore, the problem of appearance be mould surface film in early days the stage suffer damage, thereby cause " ablate (seizure) " (soldering in the press forging moulding (soldering) phenomenon), thereby greatly shorten die life.
Mould is made up of die matrix (die steel) and the cementation zone (surface film) that forms in its surface.The die steel that is used for matrix is comprising annealing, cutting and quenching/tempered operation manufacturing (in this manual, particularly, quenching is called solution treatment, and tempering is called ageing treatment) of carrying out successively usually.
As die steel (cold work die steel), used the alloy tool steel of the high Cr of high C in the past usually, for example typical JIS SKD11, and for example typical JIS SKH51 of rapid tool steel, it has the wear resistance of further raising.In these tool steel, mainly the precipitation-hardening by Cr base carbide or Mo, W or V base carbide improves hardness.In addition, for the low alloy high-speed tool steel (being commonly called the matrix rapid steel) of alloy content of C wherein, Mo, W, V etc. that improved wear resistance and toughness simultaneously, also used the reduction that obtains by JIS SKH51.
In order further to improve the performance of cold work die steel, for example patent documentation 1 to patent documentation 3 has proposed the technology of change steel-moiety.
Patent documentation 3 discloses a kind of cold work die steel, this cold work die steel has adding an amount of Ni and Al and according to the same proper C u that adds wherein of mentioned component wherein, to reduce the dimensional change degree (dimensional change) in the quenching/tempering, particularly prevent the dimensional change that tempering is expanded and caused, and improve hardness.The document has also been described the content of control C and Cr, and carbide is dispersed in little tissue subtly, thereby improves the wear resistance of steel.
On the other hand, it is not as passing through cutting in the past that patent documentation 4 discloses, then with steel quenching/tempering manufacturing, but by the technology of cutting through quenching/tempered steel (cutting after the quenching/tempering) manufacturing " pre-hardened steel ", to reduce the die production cost.Particularly, as having high hardness, and can show good machinability and can be by the steel of cold stamping processing, the document discloses the pre-hardened steel that the content of a kind of wherein C, Si and S is suitably controlled particularly.Yet the life-span of the mould that is formed by pre-hardened steel is short, and at present, this mould does not still drop into practical application.
Above-mentioned patent documentation 1 to 4 mainly prevents dimensional change at the steel of (after the ageing treatment or after temper) after the thermal treatment by control steel-moiety; But following patent documentation 5 to 7 disclose by control thermal treatment for example quench/condition in the tempering prevents the technology of dimensional change.
Among these, patent documentation 5 discloses by steel being carried out 150 to 450 ℃ low-temperaturetempering of at least one passage, and 480 to 550 ℃ high tempering of at least one passage, to prevent to quench/method of the dimensional change of steel after the tempering.
Patent documentation 7 discloses the method that realizes the predetermined hardness of steel in the following manner: the control composition of steel improves the quenching performance of steel, control preceding quenching of pearlite nose (pearlite nose) and the rate of cooling in the gas cooling subsequently, reduce the thermal treatment strain thus, keep the necessary hardness of die steel simultaneously.
Patent documentation 1:JP-A-10-330894
Patent documentation 2:JP-A-2006-152356
Patent documentation 3:JP-A-2006-169624
Patent documentation 4:JP-A-2002-241894
Patent documentation 5:JP-A-9-125204
Patent documentation 6:JP-A-2001-172748
Patent documentation 7:JP-A-2002-167644
Summary of the invention
Problem to be solved by this invention
As its essential performance, cold work die steel should have high hardness, and should be excellent aspect the dimensional change inhibition after the aforesaid thermal treatment, and in addition, it should be excellent aspect repair by welding.
Repair by welding is mainly used in the damage (particularly, the defective of cementation zone and depression) of revising and repairing mould, thus with mould regeneration and reuse; For example, usually it is used the joint welding of being undertaken by argon welding etc.As mentioned above, owing to tensile strength is at least about the increase of demand of steel of the height tension of 580MPa, greatly shortened die life; And, carry out the repair by welding of mould continually owing to reduce running cost.
Yet when the mould that will be coated with cured film carried out repair by welding, the hardness around welding portion may fluctuate greatly, thereby causes easily splitting and ablating.Particularly, the heat-affected zone after welding (HAZ) significantly softens (HAZ is softening), thereby causes the problem of shortening die life after the repair by welding.HAZ is softening be and joint portion (border between welding metal and matrix, and this can be called as " welding fusing line ") separate viewed phenomenon in a little the zone; And in this zone, it is believed that because Heating temperature is lower than the temperature in the joint portion, and cause austenitic transformation from grain refining, therefore the performance of quenching reduces, thereby increase soft ferritic phase mark, and farther that side tempering at high temperature from this zone reduces hardness thus.Fig. 1 (a) is the synoptic diagram that shows the welding of matrix and welding metal; And Fig. 1 (b) has shown Hardness Distribution among the regional A among Fig. 1 (a) with figure.As shown in Fig. 1 (b), HAZ hardness is along with big more and reduce with joint portion distance, and should the zone deliquescing.When the HAZ deliquescing, the cementation zone that forms owing to subsequently surface hardening can not fully show its provide protection, and the stage cementation zone may be impaired in early days, shortens die life thus.
As mentioned above, repair by welding is finished after can having formed the surface hardening film on matrix, perhaps can finish before forming this surface hardening film on the matrix.Particularly, be at least about in the press forging moulding of steel die of height tension of 590MPa in tensile strength, owing to be difficult to steel is pressed into the steel with desired shape in some cases, therefore steel carries out the processing of press forging moulding test and repair by welding (joint welding) in advance, afterwards, its just true press forging is shaped to required shape.In test press forging forming step, repair by welding after, there be not heat treated situation to press down forging molding steel, therefore, the softening part of HAZ possibility usually is impaired and have a defective.The defective that forms in the softening part of such HAZ may remain in the surface film that forms in the follow-up hardening treatment, and therefore residual defective may be the starting point that causes membrane damage.In addition, not only may form HAZ and soften part, and may form sclerosis part (referring to Fig. 1 and Fig. 7), and in the sclerosis part, may take place usually to rupture or split, thereby give rise to trouble.
Therefore, need provide a kind of die steel of repair by welding excellence, this die steel can prevent that the HAZ in the repair by welding is softening, and can be readily implemented in the joint welding of corner.Yet all above-mentioned patent documentations are not all considered repair by welding, and therefore, may shorten the die life after repair by welding.
The present invention considers said circumstances and carries out, and its objective is provide have high rigidity, the dimensional change inhibition after the excellent thermal treatment, and have the cold work die steel of good repair by welding, and a kind of mould be provided.
Another object of the present invention provides a kind of method that is used for making effectively cold work die steel, and described cold work die steel has high hardness, and is excellent aspect the dimensional change inhibition after thermal treatment.
The means of dealing with problems
Particularly, the present invention relates to following 1 to 12 project:
1. cold work die steel, described cold work die steel comprise by quality %:
C:0.20 to 0.60%,
Si:0.5 to 2.00%,
Mn:0.1 to 2%,
Cr:3.00 to 9.00%,
Al:0.3 to 2.0%,
Cu:1.00 to 5%,
Ni:1.00 to 5%,
Mo:0.5 to 3%, and/or W:2% following (comprising 0%),
S:0.10% following (not comprising 0%),
Wherein satisfy following condition (1) to (3) { wherein each square brackets [] is meant the content (%) of each element }:
(1)[Cr]×[C]≤3.00，
(2) [Cu]/[Ni]: 0.5 to 2.2,
(3) [Mo]+0.5 * [W]: 0.5 to 3.0%,
And surplus is iron and unavoidable impurities.
2. according to the 1st described cold work die steel, described cold work die steel also comprises V:0.5% following (not comprising 0%).
3. according to the 1st or 2 described cold work die steel, it is at least a element among Ti, Zr, Hf, Ta and the Nb of being selected from that (does not comprise 0%) below 0.5% that described cold work die steel also comprises total amount.
4. according to each described cold work die steel in the 1st to 3, described cold work die steel also comprises Co:10% following (not comprising 0%).
5. according to each described cold work die steel in the 1st to 4, described cold work die steel has the martensite point (Ms point) more than 170 ℃, and described martensite point is expressed from the next:
The Ms point
＝550-361×[C]-39×[Mn]-35×[V]-20×[Cr]
-17×[Ni]-10×[Cu]-5×([Mo]+[W])
+15×[Co]+30×[Al]
{ wherein each square brackets [] is represented the content (%) of each element }.
6. one kind by using the mould that obtains according to each described cold work die steel in the 1st to 5.
7. method that is used to make cold work die steel, described method comprises the following steps:
Composition according to claim 1 is satisfied in preparation, and satisfies following condition (4) steel of { wherein each square brackets [] is represented the content (%) of each element }:
(4) [Cu]/[C]: 4.0 to 15;
And, described steel is carried out solution treatment and ageing treatment under the condition that satisfies following formula (5):
TA-10≤T2≤TA+10(5)
Wherein,
TA＝0.29×T1-2.63×[Cu]/[C]+225，
T1 be meant solid solution temperature (℃), and
T2 be meant aging temp (℃).
8. according to the 7th described manufacture method, wherein said steel also comprises V:0.5% following (not comprising 0%).
9. according to the 7th or 8 described manufacture method, it is at least a element among Ti, Zr, Hf, Ta and the Nb of being selected from that (does not comprise 0%) below 0.5% that wherein said steel also comprises total amount.
10. according to each described manufacture method in the 7th to 9, wherein said steel also comprises Co:10% following (not comprising 0%).
11. according to each described manufacture method in the 7th to 10, wherein said steel has the martensite point (Ms point) more than 170 ℃, described martensite point is expressed from the next:
The Ms point
＝550-361×[C]-39×[Mn]-35×[V]-20×[Cr]
-17×[Ni]-10×[Cu]-5×([Mo]+[W])
+15×[Co]+30×[Al]
{ wherein each square brackets [] is meant the content (%) of each element }.
12. mould that obtains according to each described manufacture method in the 7th to 11.
The invention advantage
According to cold work die steel of the present invention, owing to like that suitably control alloying constituent as mentioned above, so steel has high rigidity, excellence aspect the dimensional change inhibition after thermal treatment, and have good repair by welding.Therefore, by adopting mould that above-mentioned cold work die steel obtains advantageously to be particularly useful as the forming mould that steel plate that tensile strength is at least about the height tension of 590MPa is used, and can further prolong the life-span of mould, especially the life-span of its mould after repair by welding.
In addition, in manufacture method of the present invention, owing to suitably control steel-moiety and be used for solution treatment and the condition of ageing treatment, therefore can make cold work die steel effectively with the dimensional change inhibition excellence after high rigidity and the thermal treatment.Therefore, the mould that manufacturing method according to the invention obtains advantageously is particularly useful as the forming mould that steel plate that tensile strength is at least about the height tension of 590MPa is used, and can further prolong the life-span of mould, especially the life-span of its mould after repair by welding.
The accompanying drawing summary
Fig. 1 (a) and 1 (b) are the figure that schematically shows the welded condition of matrix and welding metal, and wherein Fig. 1 (a) is the cross-sectional view of welding portion, and Fig. 1 (b) is the figure that schematically shows the Hardness Distribution among the regional A of Fig. 1 (a).
Fig. 2 (a) is presented at the light micrograph that is formed and be coated with the state of the ablation that the surface of the mould of TiN film occurs by die steel JIS SKD11; Fig. 2 (b) and Fig. 2 (c) its local light micrograph that amplifies of respectively doing for oneself; And Fig. 2 (d) is the light micrograph of the die matrix before applying with the TiN film.
Fig. 3 (a) is the sketch chart that shows the shape of the welding piece of using in an embodiment; Fig. 3 (b) is the amplification cross-sectional view of groove.
Fig. 4 is the sketch chart that schematically shows the state of the test specimen of handling by buttering.
Fig. 5 is the sketch chart that shows the shape of the charpy impact test specimen that uses in an embodiment.
Fig. 6 is the figure that shows the relation between ratio [Cu]/[Ni] and the softening width of HAZ.
Fig. 7 is the figure that shows the Hardness Distribution curve;
Fig. 8 is the figure that shows the relation between ratio [Cu]/[C] and the size changing rate (mean value, maximum value).
Fig. 9 schematically shows the figure of ageing treatment to the influence of hardness and dimensional change (size changing rate).
Figure 10 schematically shows the figure of ageing treatment to the influence of dimensional change amount.
Implement best mode of the present invention
Describe the present invention below in detail.In this manual, per-cent in mass, unless indicate particularly in addition.All percentage expression formulas by mass are identical with all expression formulas by weight.
Describe the cold work die steel of a first aspect of the present invention in detail.
For the cold work die steel that is improved aspect special hardness, dimensional change inhibition after the thermal treatment and the repair by welding among the necessary various performances of cold work die steel is provided, the inventor has at first studied the conventional mould that is formed by JIS SKD11 or matrix rapid steel, to clarify the reason that the die surface film is impaired and generation is ablated.
Fig. 2 (a) is presented at the light micrograph that is formed and be coated with the state of the ablation that occurs on the surface of mould of TiN film by die steel JIS SKD11; And Fig. 2 (b) and Fig. 2 (c) its local light micrograph that amplifies of respectively doing for oneself.For for reference, Fig. 2 (d) is the light micrograph of the die matrix before applying the TiN film.In Fig. 2 (d), the part that looks like white is the Cr carbide.As from Fig. 2 (b) and Fig. 2 (c), obviously finding out, in the zone of peeling off of filming, separate out hard and coarse Cr carbide (mainly contain Cr and Fe, and be of a size of the carbide of about 1 to 50 μ m) from the teeth outwards, and form the crackle that originates from carbide.
Find out from above-mentioned analytical results, the inventor thinks that the starting point of ablating is above-mentioned thick Cr carbide, and when preventing the formation of carbide as much as possible (perhaps when not forming carbide), can prevent that then surface coatings from peeling off, and can keep long die life.
Based on above-mentioned discovery, the inventor has carried out further research.As a result of, the inventor has been found that the following fact: improve above-mentioned performance thus for the formation that prevents thick carbide, it is highly important that and suitably control the C amount, in addition, (positively) adds various alloying constituents on one's own initiative, suitably controls the design of alloying constituent therefrom.Particularly, the inventor has been found that, in order to obtain required performance, effectively add alloying constituent (particularly Al, Cu, Ni, Mo and W) on one's own initiative, thereby the precipitation-hardening of passing through the alloying constituent that added improves hardness, rather than by improving hardness, and mainly due to this reason, can utilize precipitation-hardening that the Al-Ni intermetallic compound causes and the carbide of Mo or W and C to form the secondary hardening that causes as controlling by carbide in the past.The inventor has carried out further experiment, and has reached formation of the present invention.
In this manual, " having high rigidity " be meant when according to the methods analyst sample described in the embodiment that provides the below part when determining its highest hardness, highest hardness is defined as the sample with high rigidity for those samples of 650HV at least.
In a first aspect of the present invention, " at the dimensional change after the thermal treatment (size changing rate) " is by following definite: before ageing treatment and afterwards, analytic sample to be determining its size on these three directions of thickness, width and length, and adopt its mean value with and maximum value and minimum value between difference the two estimate dimensional change.For convenience of description, the former is called as " mean value of size changing rate "; And the latter is called as " size changing rate difference ".The difference of the technology of a first aspect of the present invention and patent documentation 2 is, in the present invention, based on the dimensional change after " mean value of size changing rate " and " size changing rate difference " the two evaluation thermal treatment, and in the document, only measure the former (mean value of size changing rate).Result by experiment, the inventor is verified, for the dimensional change after the abundant inhibition thermal treatment, reduction as the mean value of the size changing rate in patent documentation 2 is unsatisfactory, and requisite is the dimensional change (fluctuation) that is reduced on these three directions of thickness, width and length, even and can reduce the mean value of size changing rate, in some cases, the size changing rate difference also may increase (vice versa) (referring to embodiment given below).In a first aspect of the present invention, phrase " dimensional change after the thermal treatment little (promptly; dimensional change inhibition excellence) " is meant when measuring the dimensional change of thermal treatment front and back according to the method described in the embodiment part given below, the mean value of size changing rate is in ± 0.05% scope, and the size changing rate difference is below 0.08%.
In this manual, adopt the softening width evaluation " repair by welding " of HAZ." repair by welding is excellent " is meant when softening width according to the method mensuration HAZ described in the embodiment part that provides below, in its scope below 6.5mm.
Be described in detail in the composition of steel in a first aspect of the present invention below.In steel, not only control content to the contributive alloying element of precipitation-hardening, it is fallen in the predetermined scope, and, suitably control the balance of predetermined-element as by following formula (1) to (3) definition, improve the above-mentioned performance of steel thus.As shown in the embodiment that provides below, any one those that do not satisfy in these conditions can not have required performance.Particularly, in the present invention, requisite is all to join Cu, Ni and this three of Al in the steel; And for example, do not contain the inaccessiable required effect in any steel capital (referring to embodiment given below) in these compositions in above-mentioned patent documentation 1 or the patent documentation 3, this is that the inventor confirms by experiment.
Reference is " repair by welding " (by the softening width evaluation of HAZ) and " the dimensional change inhibitions before and after thermal treatment " (estimating by size changing rate on the machine direction and size changing rate difference simultaneously), these are the principle targets that will improve in a first aspect of the present invention, are described in the composition of steel in a first aspect of the present invention below simply.
At first, in order to improve repair by welding (in order to reduce the softening width of HAZ), in principle, importantly suitably control the upper limit of [Cr] * [C], Ms point (lower limit), C amount (lower limit), Al amount (lower limit), Ni amount (lower limit), [Cu]/[Ni] (upper and lower bound), [Mo]+0.5 * [W] (lower limit) and V amount (upper limit).Particularly, as the design guidance policy that is used to reduce the softening width of HAZ, be not to use the sclerosis due to forming by martensite, but the precipitation-hardening (for example, ε-Cu, Ni-Al intermetallic compound or Ni-Mo intermetallic compound) of utilization by being reduced to about 0.2 to 0.60% C amount and causing by interpolation alloying constituent (being mainly Al, Cu, Ni, Mo and W).These precipitates are the tiny coherence precipitates in the matrix, and they significantly improve the hardness of steel.
Particularly, Cu, Ni and Al are important as the precipitation-hardening element, and they are the elements that the HAZ remollescent suppressed to have very big contribution.Any steel capital that does not wherein add these elements basically can not have the softening restraining effect of required HAZ, and this is that the inventor is through experiment confirm.
In addition, as being confirmed by the inventor, ratio [Cu]/[Ni] ratio of ([Cu] with [Ni]) and HAZ be softening to suppress to have relation closely, and can to suppress HAZ softening by suitably controlling above-mentioned ratio.Fig. 6 shows the figure of ratio [Cu]/[Ni] to the influence of the softening width of HAZ, wherein measures the softening width of HAZ according to the method described in the embodiment that provides below.In the figure, the 31st to 35 and No. 37 in the 7th, 8 and No. 10 data in the following table 3 and the table 4 data are drawn.As shown in Figure 6, ratio [Cu]/[Ni] has relation closely with the softening width of HAZ; And as can be seen, it is fallen in 0.5 to 2.2 the scope, can control the softening width of HAZ it is fallen into by (6.5mm is following) in the framework of the present definition by controlling above-mentioned ratio.
On the other hand, in order to reduce the dimensional change after the thermal treatment as much as possible, the upper limit, C amount (upper limit), Si amount (upper limit), Mn amount (upper limit), Ms point (lower limit), Al amount (upper limit), Ni amount (upper limit), the Cr that importantly suitably control the product ([Cr] * [C]) of Cr and C content measure (upper limit) and [Mo]+0.5 * [W] (upper limit).The present invention is based on low C, therefore, the Ms point is high, and the formation of residual austenite is certainly little, in addition, suitably controls the content of alloying constituent such as Cu, Ni and Al.Therefore, in the present invention, can significantly delay after about 400 to 550 ℃ ageing treatment or the expansion and the contraction of the steel of surface hardening after handling.Its reason is thought as follows.Promptly, because the adding of above-mentioned alloying constituent, therefore for example in about 400 to 500 ℃ low temperature range, mainly form ε-Cu, in the scope of about 450 to 530 ℃ moderate temperature, mainly form Ni-(Al, Mo) intermetallic compound, and in about 500 to 550 ℃ high temperature range, mainly form the Mo-V carbide; Yet, because the crystalline structure (FCC structure) of these precipitates is different from matrix (BCC structure), so the volumetric shrinkage of steel, thereby facilitate the dimensional change after the thermal treatment to suppress.In addition, in the present invention, separate out to delay thick Cr carbide as far as possible owing to be carried out to the branch design, crystalline structure in any direction is isotropic, even and in making large size and complicated mould structure, also can suppress the dimensional change after its thermal treatment effectively.
Composition of steel in a first aspect of the present invention is described below.
C:0.20 to 0.60%
C is the element of guaranteeing hardness and wear resistance and facilitating the softening width of HAZ to reduce.According to the CVD method, forming on the surface of die matrix under the situation of carbide membrane such as VC or TiC, when C concentration is low, the insufficient problem of film thickness may take place.Consider this point, show effectively above-mentioned effect C amount be limited to 0.20% down.Preferably, the C amount is more than 0.22%.Yet when it adds when too much, residual austenite may increase, and under the situation that does not have high-temperature aging to handle, steel can not have required hardness, and in addition, steel may be at the ageing treatment after, and its dimensional change may increase.Therefore, C amount on be limited to 0.60%.Preferably, the C amount is below 0.50%, more preferably below 0.45%.
Si:0.5 to 2.00%
Si is the element that can be used as deoxidant element in steel is made, and this element impels hardness to improve, and guarantees the machinability of steel.In addition, Si can be used for preventing the martensitic temper softening in the matrix and suppresses the softening width of HAZ.In order to show these effects effectively, the following of Si amount is limited to 0.5%.Yet when it adds when too much, segregation may increase, and the dimensional change after the thermal treatment also may increase, and in addition, toughness may reduce.Therefore, be limited to 2.00% on it.The lower limit of Si amount is preferably 1%, and more preferably 1.2%.On the other hand, the upper limit of Si amount is preferably 1.85%.
Mn:0.1 to 2%
Mn can be used for guaranteeing quenching the element of performance.Yet when it adds when too much, the Ms point significantly reduces, and residual austenite increases, and therefore under the situation that does not have high-temperature aging to handle, steel can not have required hardness.Consider these, limit Mn content it is fallen in the above-mentioned scope.The lower limit of Mn amount is preferably 0.15%; On the other hand, the upper limit of Mn amount is preferably 1%, and more preferably 0.5%, also more preferably 0.35%.
Cr:3.00 to 9.00%
Cr is the element that can be used for guaranteeing predetermined hardness.When the Cr amount was less than 3.00%, the quenching performance may be poor, and may partly form bainite so that reduce hardness, and can not guarantee wear resistance.Preferably, the Cr amount is more than 3.5%, more preferably more than 4.0%.Yet, when it adds when too much, may form thick Cr carbide in a large number, and steel may shrink after thermal treatment, and the film weather resistance may reduce.Therefore, composition on be limited to 9.00%.The Cr amount is preferably below 7.0%, more preferably below 6.5%, also more preferably below 6.0%.
Al:0.3 to 2.0%
Al is by Al-Ni intermetallic compound Ni for example
3The precipitation strength of Al improves the necessary element of hardness, and this helps the inhibition to the softening width of HAZ.In addition, Al also can be used as reductor.Consider these, the following of Al is limited to 0.3%.Yet when it adds when too much, segregation may increase, and the dimensional change after thermal treatment (particularly size changing rate difference) may increase, and toughness may reduce.Therefore, this composition on be limited to 2.0%.Preferably, Al amount is 0.50% to 1.8%, more preferably 0.7% to 1.6%.
Cu:1.00 to 5%
Cu is that the precipitation strength by ε-Cu improves the necessary element of hardness, and this helps the inhibition to the softening width of HAZ.Yet when it adds when too much, steel may split in forging.Therefore, be limited to 5% on it.The Cu amount is preferably 2.0% to 4.0%.
Ni:1.00 to 5%
Ni is by Al-Ni intermetallic compound Ni for example
3The precipitation strength of Al improves the necessary element of hardness, and this helps the inhibition to the softening width of HAZ.In addition, when making up with Cu, Ni is to delaying by the caused hot-work fragility of the excessive adding of Cu and preventing that splitting in the forging process from being effective.Yet when it adds when too much, residual austenite may increase, and under the situation that does not have high-temperature aging to handle, and steel can not be guaranteed the hardness of being scheduled to, and in addition, steel may be at the thermal treatment after.The Ni amount is preferably 1.5% to 4.0%.
Mo:0.5 to 3% and/or (comprise 0%) below the W:2%
Mo and W form M
6C carbide and formation Ni
3Two kinds of elements of Mo intermetallic compound, and help precipitation strength.Yet when Mo and W add when too much, above-mentioned carbide may too much form so that reduce toughness, and in addition, the dimensional change after the thermal treatment (particularly size changing rate difference) may increase.Therefore, the present invention defines above-mentioned scope.In the present invention, the Mo composition that is absolutely necessary, and W is optional elements, but steel can contain them simultaneously.Mo content is preferably 0.5% to 3%, and more preferably 0.7% to 2.5%.W content is preferably below 2%, more preferably below 1.5%.
S:0.10% following (not comprising 0%)
S is the element that can be used for guaranteeing machinability.Yet when it adds when too much, it may cause weld seam to break, thus it on be limited to 0.10%.The S amount is preferably below 0.07%, more preferably below 0.05%, also more preferably below 0.025%.
In addition, a first aspect of the present invention must satisfy following condition (1) to (3) { wherein each square brackets [] is meant the content (%) of each element }.
(1)[Cr]×[C]≤3.00
Limit above-mentioned condition (1), to delay the formation of thick Cr carbide.When the product of [Cr] and [C] surpassed 3.00, the dimensional change after the thermal treatment may increase, and the weather resistance possible deviation of surface film.The product of [Cr] and [C] is preferably below 1.80, more preferably below 1.70.For the viewpoint that prevents the dimensional change after thermal treatment, its lower limit is excellent littler.Yet, consider that from the caused above-mentioned effect of the interpolation that shows Cr and C effectively its lower limit is preferably about 0.8.
(2) [Cu]/[Ni]: 0.5 to 2.2
Above-mentioned condition (2) is defined (referring to embodiment given below) mainly as the parameter of precipitation strength that utilizes ε-Cu and the softening width of inhibition HAZ.In order to show these effects effectively, [Cu] is restricted to 0.5 with the ratio of [Ni].Yet when ratio was too big, it may cause in forging process split.Therefore, be limited to 2.2 on it.Preferably, this ratio is 0.7 to 1.5, more preferably 0.85 to 1.2.
(3) [Mo]+0.5 * [W]: 0.5 to 3.0%
As described in the above, the Mo and the W that constitute above-mentioned condition (3) are the elements that helps precipitation strength.Above-mentioned condition (3) is restricted to by their precipitation strength guarantees the parameter that hardness improves, and softening width inhibition also is effective to HAZ.In above-mentioned condition (3), the coefficient of [W] (0.5) is that the nucleidic mass of considering Mo is about 1/2 the limiting of nucleidic mass of W.In order to show these effects effectively, the following of above-mentioned condition (3) is limited to 0.5%.Yet, when the amount of Mo and W is too many, may consequently reduce toughness by the above-mentioned carbide of excessive formation, and in addition, if like this, then the dimensional change after the thermal treatment (particularly size changing rate difference) may increase.Therefore, above-mentioned condition (3) on be limited to 3.0%.Preferably, the following of above-mentioned condition (3) is limited to 1.0%, and more preferably 1.2%; And on the other hand, its upper limit is preferably 2.8%.
Composition of steel in a first aspect of the present invention is as described above, and surplus is iron and unavoidable impurities.Unavoidable impurities is the element that for example may be contained in inevitably in its manufacturing processed in the steel.For example, they comprise P, N and O.The P amount is preferably about below 0.05%, more preferably below 0.03%.The N amount is preferably below about 350ppm, more preferably below the 200ppm, also more preferably below the 150ppm.The O amount is preferably below about 50ppm, more preferably below the 30ppm, also more preferably below the 20ppm.
In the present invention, can further randomly add following ingredients to improve other performance of steel.
V:0.5% following (not comprising 0%)
V owing to form carbide for example VC help to increase hardness, and be that the softening width of HAZ is suppressed effective elements.In addition, when handling for example steam nitriding, bath salt nitriding or plasma nitridation by nitriding form diffusion hardened layer on matrix surface, V is for increasing surface hardness and being effective for increasing case depth.In order to show these effects effectively, the V amount is preferably about more than 0.05%.Yet when it adds when too much, the meltage of C may reduce, and the hardness of the martensitic stucture of matrix may descend.Therefore, its upper limit is preferably 0.5%.The V amount is more preferably below 0.4%, also more preferably below 0.30%.
The total amount that is selected from least a element among Ti, Zr, Hf, Ta and the Nb is (not comprise 0%) below 0.5%.
These elements all are nitride forming elements, and these fine dispersion and grain refinings owing to nitride and AlN help toughness to increase.In order to show these effects effectively, preferably, the Ti amount is for about more than 0.01%, and the Zr amount is for about more than 0.02%, and the Hf amount is for about more than 0.04%, and the Ta amount is for about more than 0.04%, and the Nb amount is for about more than 0.02%.Yet when these elements add when too much, the meltage of C may reduce, and martensite hardness may reduce.Therefore, the total amount of above-mentioned element is preferably 0.5%.More preferably, the total amount of these elements is below 0.4%, also more preferably below 0.30%.These elements can separately or make up and add.
Co:10% following (not comprising 0%)
To increase steel hardness thus be effective elements to Co to rising Ms point and to reducing residual austenite.In order to show above-mentioned effect effectively, the Co amount is preferably about more than 1%.Yet when it adds when too much, cost may increase.Therefore, its upper limit is preferably 10%.The upper limit of Co amount more preferably 5.5%.
Martensite point (Ms point) 〉=170 ℃
The Ms point
＝550-361×[C]-39×[Mn]-35×[V]-20×[Cr]
-17×[Ni]-10×[Cu]-5×([Mo]+[W])
+15×[Co]+30×[Al]
{ wherein each square brackets [] is represented the content (%) of each element }
In the present invention, the Ms point mainly is the index of the hardness of steel and the dimensional change inhibition after the thermal treatment.When the Ms point was lower than 170 ℃, then residual austenite may increase, and under the situation that does not have high-temperature aging to handle, steel can not have required hardness, and in addition, if like this, then steel may be at the thermal treatment after.The Ms point is preferably higher, more preferably more than 230 ℃, also more preferably more than 235 ℃, also more preferably more than 250 ℃.For the viewpoint of above-mentioned effect, the upper limit that Ms is ordered is not subjected to concrete qualification.Yet, consider and add effect and the effect that above-mentioned element is ordered to set up Ms that its upper limit is preferably about 350 ℃, more preferably 320 ℃.
The present invention also comprises the mould by utilizing above-mentioned die steel to obtain.The method of mfg. moulding die is not subjected to concrete qualification.For example, that mentions has a method that may further comprise the steps: above-mentioned steel is prepared into the fusing form, then the steel that is softened (is for example carried out heat forged and annealing, kept 7 hours at about 700 ℃, average rate of cooling with about 17 ℃/hr is cooled to about 400 ℃ in stove then, afterwards, with its further cooling similarly), be cut to predetermined shape in rough machined mode afterwards, then it is processed to carry out solution treatment in about 950 to 1150 ℃ temperature, subsequently it is carried out ageing treatment at about 400 to 530 ℃, thereby make it have predetermined hardness.
Then, describe according to a second aspect of the invention the method that is used to make cold work die steel below in detail.
The inventor has carried out further research makes them satisfy the dimensional change inhibition after the cold work die steel of required performance, particularly hardness, the thermal treatment and the improved cold work die steel of these performances (prolonging in the life-span aspect the damage of repair by welding mould) of repair by welding to provide.As a result, the inventor has been found that when suitably controlling composition of steel, then can reach required purpose (a first aspect of the present invention).
After a first aspect of the present invention, the inventor has further carried out various researchs based on the formation of disclosed composition of steel in existing patent application, with the dimensional change inhibition after the further raising Heat Treatment Of Steel.As a result, the inventor has been found that when the steel that uses a first aspect of the present invention and when it is being fit to carry out solution treatment and ageing treatment under the condition, can obtain the further cold work die steel of raising of dimensional change inhibition after the thermal treatment effectively.
Particularly, the manufacture method of a second aspect of the present invention is characterised in that, in a first aspect of the present invention, is defined for particularly and makes the favourable of cold work die steel that the dimensional change inhibition after the thermal treatment further improves effectively and create conditions.Particularly, present method is characterised in that solid solution temperature and aging temp are limited by the parameter (Cu by mass and the ratio of C) that helps most the dimensional change inhibition after the thermal treatment.Manufacture method according to a second aspect of the invention, even without any special thermal treatment for example under the situation of " the two stage temper of at least 1 passage " in the patent documentation 5 or the subzero processing in the patent documentation 6, also can be only obtain to have cold work die steel, so the producibility of this method is unusual excellence than the dimensional change inhibition after the also better thermal treatment in the past by 1 passage temper (ageing treatment) the same as before.
For the production method that is used for this cold work die steel, the operation from a first aspect of the present invention to a second aspect of the present invention is described at first.
The inventor has at first studied the conventional mould that is formed by JIS SKD11 or matrix rapid steel, to clarify the reason that the die surface film is impaired and generation is ablated.As a result, the inventor finds, in the zone of stripping film, separated out rigidity and thick Cr carbide (carbide that is mainly Cr or Fe with size of about 1 to about 50 μ m) from the teeth outwards, and begins to form from carbide and split.
From above-mentioned analytical results, the inventor thinks that the starting point of ablating is above-mentioned thick Cr carbide, and when having served as the formation that prevents carbide as much as possible (perhaps, when not forming carbide), can prevent that then surface coatings from peeling off, and can keep long die life.
Based on above-mentioned discovery, the inventor has carried out further research.As a result, the inventor has found the following fact: to improve above-mentioned performance thus in order preventing to form thick carbide, to it is highly important that and suitably control the C amount, in addition, add various alloying constituents on one's own initiative, suitably control design of alloy thus.Particularly, the inventor has been found that, in order to obtain required performance, effectively add alloying constituent (particularly Al, Cu, Ni, Mo and W) on one's own initiative, thereby owing to the precipitation-hardening of the alloying constituent of being added improves hardness, rather than the same as before control by carbide improve hardness, mainly due to this reason, can utilize the carbide of precipitation-hardening due to the Al-Ni intermetallic compound and Mo or W and the C secondary hardening due to forming.
The above-mentioned inventor of being realizes the method for a first aspect of the present invention thus.Afterwards, the inventor further studies to provide has high productive manufacture method, this manufacture method can be only by a passage solution treatment/ageing treatment the same as before, easily make cold work die steel, and need not any special thermal treatment with the dimensional change inhibition after the much more excellent thermal treatment.The result, the inventor finds, in the solution treatment and ageing treatment of above-mentioned steel, when treatment temp (solid solution temperature and aging temp) suitably is defined as with to the dimensional change inhibition after thermal treatment contribution maximum " Cu by mass and the ratio of C " when relevant, as among the embodiment that provides below, can reach its intended purposes; And the inventor has finished the manufacture method of a second aspect of the present invention like this.
Particularly, the inventor is verified, when solid solution temperature (℃) represent by T1, aging temperature (℃) represent that by T2 the mass ratio of Cu and C is by [Cu]/[C] expression, and by following formula:
0.29×T1-2.63×[Cu]/[C]+225
When the numerical value of expression is represented by TA, then satisfy following formula (5) at T2:
TA-10≤T2≤TA+10(5)，
Scope in (promptly, in the scope of TA ± 10 ℃) solution treatment and ageing treatment process produced and had the steel that utmost point excellent size changes inhibition, reason is the scope (referring to the table 7 among the embodiment given below) that its mean sizes velocity of variation after thermal treatment and overall dimension velocity of variation (their details is described below) satisfy a second aspect of the present invention.
In this manual, mentioned " solution treatment " has the implication identical with quench treatment; And " ageing treatment " has the implication identical with temper.
In this manual, " high rigidity " is meant that the hardness according to the mensuration of the method for description in the embodiment part given below is at least 650HV.
In a first aspect of the present invention, " dimensional change after the thermal treatment (size changing rate) " is by following mensuration: analytic sample to be measuring its size on thickness (Δ x), width (Δ y) and three directions of length (Δ z) before and after the ageing treatment, and the maximum value (absolute value) of employing mean value [Δ x+ Δ y+ Δ z)/3] and above-mentioned Δ x, Δ y and Δ z the two estimate dimensional change.For convenience of description, the former is called " mean value of size changing rate or mean sizes velocity of variation "; And the latter is called " maximum value of size changing rate or overall dimension velocity of variation ".The technology difference of a second aspect of the present invention and patent documentation 2 is, in a second aspect of the present invention, based on the dimensional change after " mean value of size changing rate " and " maximum value of size changing rate " evaluation thermal treatment, and in this reference, only measure the former (mean value of size changing rate).Result by experiment, the inventor is verified, for the dimensional change after the abundant inhibition thermal treatment, as with patent documentation 2 in the reduction of mean value of size changing rate make us dissatisfied, and requisite is the dimensional change (fluctuation) that is reduced on these three directions of thickness, width and length, although and can reduce the mean value of size changing rate, also may increase the difference (vice versa) (referring to embodiment given below) of size changing rate in some cases.In a second aspect of the present invention, phrase " dimensional change after the thermal treatment little (promptly; dimensional change inhibition excellence) " is meant when the method for describing in according to embodiment given below part is measured dimensional change before and after the thermal treatment, the mean value of size changing rate is in ± 0.03% scope, and the maximum value of size changing rate (absolute value) is below 0.05%.
The judgement criteria of a second aspect of the present invention of mentioning in the above (method and level thereof) and above-mentioned first aspect difference of the present invention be following some.
At first, in a first aspect of the present invention and in a second aspect of the present invention, adopt " mean value of size changing rate " judgement criteria as the dimensional change after the thermal treatment.Yet in a first aspect of the present invention, acceptance line is ± 0.05%.And in a second aspect of the present invention, acceptance line is ± 0.03%, and than stricter in a first aspect of the present invention.
In addition, in a first aspect of the present invention, employing be maximum value and the difference between the minimum value (absolute value) among " size changing rate difference " or above-mentioned Δ x, Δ y and the Δ z; And in a second aspect of the present invention, employing be " maximum value of size changing rate " mentioned in the above.This is based on following understanding: " in order to provide the dimensional change inhibition than steel more excellent in a first aspect of the present invention; wherein the dimensional change after the thermal treatment (fluctuation) must be reduced as much as possible for the part of maximum (maximum value) ", and on this basis, " the size changing rate difference " in the part of using a first aspect of the present invention, described, in a second aspect of the present invention, also use " maximum value of size changing rate ".As shown in the embodiment that provides below, some steel that satisfies " the size changing rate difference " that define in a first aspect of the present invention can not satisfy " maximum value of size changing rate " (referring to the embodiment given below) that defines in a second aspect of the present invention.In a second aspect of the present invention, these steel can not be described as " steel " with the dimensional change inhibition after the excellent thermal treatment.
Composition of steel in a second aspect of the present invention is discussed in more detail below.In steel, not only control help precipitation-hardening alloying element content so that its fall in the predetermined scope, and as following formula (1) to (4) limit, suitably control the balance of predetermined-element, improve the above-mentioned performance of steel thus.As shown in the embodiment that provides below, any one those steel capital of not satisfying in these requirements can not have required performance.Particularly, in a second aspect of the present invention, requisite is that all Cu, Ni and Al are joined in the steel; For example, can not reach required effect as any the steel capital that does not contain in above-mentioned patent documentation 1 or the patent documentation 3 in these compositions, this is that the inventor confirms by experiment.
Particularly, in a second aspect of the present invention, for the dimensional change after the thermal treatment is minimized, importantly not only suitably control constitute [Cu] of above-mentioned formula (5) and the mass ratio of [C], and the product (upper limit of [Cr] * [C]), C amount (upper limit), Si amount (upper limit), Mn amount (upper limit), Ms point (lower limit), Al amount (upper limit), Ni amount (upper limit), the Cr that suitably control the content of Cr and C measure (upper limit) and [Mo]+0.5 * [W] (upper limit).The present invention is based on low-C, therefore, wherein the Ms point is high, and the formation of residual austenite is few naturally, in addition, suitably controls for example content of Cu, Ni and Al of alloying constituent.Therefore, in the present invention, can delay steel significantly after about 400 to 550 ℃ ageing treatment or expansion and contraction after surface hardening is handled.Its reason is thought as follows.That is, because the interpolation of above-mentioned alloying constituent, for example, main ε-the Cu that forms in about 400 to 500 ℃ temperature range, Ni-(Al, Mo) intermetallic compound is mainly in the scope of about 450 to 530 ℃ moderate temperature, and the Mo-V carbide is mainly in about 500 to 550 ℃ high temperature range; Yet, because the crystalline structure (FCC structure) of these precipitates is different from matrix (BCC structure), so the volumetric shrinkage of steel, thereby help the dimensional change after the thermal treatment to suppress.In addition, in the present invention, owing to separating out and be carried out to branch design in order to delay thick Cr carbide as much as possible, therefore crystalline structure all is isotropy in any direction, even and in the mould structure of making large size and complexity, can suppress its dimensional change after thermal treatment effectively.
In a second aspect of the present invention, mainly, suitably the upper limit of control [Cr] * [C], Ms point (lower limit), C amount (lower limit), Al amount (lower limit), Ni amount (lower limit), [Cu]/[Ni] (upper and lower bound), [Mo]+0.5 * [W] (lower limit) and V measure (upper limit), to improve repair by welding (to suppress the softening width of HAZ).Particularly, as the design guidance policy that is used to reduce the softening width of HAZ, not to adopt the sclerosis that forms by martensite, but adopt by the C amount being reduced to about 0.2 to 0.60% low like that and interpolation by alloying constituent (being mainly Al, Cu, Ni, Mo and W) precipitation-hardening (for example, ε-Cu, Ni-Al intermetallic compound or Ni-Mo intermetallic compound).These precipitates are the tiny coherence precipitates in the matrix, and they significantly increase steel hardness.
Particularly, Cu, Ni and Al are important as the precipitation-hardening element, and are to go far towards to suppress HAZ remollescent element.Any steel capital of fully not adding in these elements can not have the softening effect that suppresses of required HAZ, and this is that the inventor confirms by experiment.
In addition, [Cu]/[Ni] ratio (ratio of [Cu] and [Ni]) suppresses in close relations with HAZ is softening, and as by inventor's confirmation, by suitably controlling above-mentioned ratio, it is softening to suppress HAZ.
Composition of steel in a second aspect of the present invention is described below.
C:0.20 to 0.60%
C is the element of guaranteeing hardness and wear resistance and helping to reduce the softening width of HAZ.Form carbide membrane on according to the surface of CVD method at die matrix for example under the situation of VC or TiC, when C concentration was low, then contingent problem was the film thickness deficiency.Consider this, the following of C amount that fully suppresses above-mentioned effect is limited to 0.20%.Preferably, the C amount is more than 0.22%.Yet when it adds when too much, residual austenite may increase, and under the situation that does not have high-temperature aging to handle, steel can not have required hardness, and in addition, steel may be at the ageing treatment after, and its dimensional change may increase.Therefore, C amount on be limited to 0.60%.Preferably, the C amount is below 0.50%, more preferably below 0.45%.
Si:0.5 to 2.00%
Si is the element that can be used as deoxidant element in steel is made, and this element helps the machinability that improves hardness and guarantee steel.In addition, Si can be used for preventing the martensitic temper softening in the matrix and suppresses the softening width of HAZ.In order to show these effects effectively, the following of Si amount is limited to 0.5%.Yet when it adds when too much, segregation may increase, and the dimensional change after the thermal treatment also may increase, and in addition, toughness may reduce.Therefore, be limited to 2.00% on it.The lower limit of Si amount is preferably 1%, and more preferably 1.2%.On the other hand, the upper limit of Si amount is preferably 1.85%.
Mn:0.1 to 2%
Mn can be used for guaranteeing quenching the element of performance.Yet when it adds when too much, the Ms point significantly reduces, and residual austenite increases, and makes that steel can not have required hardness under the situation that does not have high-temperature aging to handle.Consider these, limit Mn content so that it falls in the above-mentioned scope.The lower limit of Mn amount is preferably 0.15%; On the other hand, the upper limit of Mn amount is preferably 1%, and more preferably 0.5%, also more preferably 0.35%.
Cr:3.00 to 9.00%
Cr is the element that can be used for guaranteeing predetermined hardness.When the Cr amount was less than 3.00%, the performance of then quenching may be poor, and may partly form bainite so that reduce hardness, and can not guarantee wear resistance.Preferably, the Cr amount is more than 3.5%, more preferably more than 4.0%.Yet,, may form thick Cr carbide in a large number, and steel may shrink after thermal treatment, and the film weather resistance may reduce when it adds when too much.Therefore, this composition on be limited to 9.00%.The Cr amount is preferably below 7.0%, more preferably below 6.5%, also more preferably below 6.0%.
Al:0.3 to 2.0%
Al is by Al-Ni intermetallic compound Ni for example
3The precipitation strength of Al increases the necessary element of hardness, and this helps to suppress the softening width of HAZ.In addition, Al also can be used as reductor.Consider these, the following of Al is limited to 0.3%.Yet when it adds when too much, segregation may increase, and the dimensional change after the thermal treatment (particularly size changing rate difference) may increase, and toughness may reduce.Therefore, this composition on be limited to 2.0%.Preferably, Al amount is 0.50% to 1.8%, more preferably 0.7% to 1.6%.
Cu:1.00 to 5%
Cu is that the precipitation strength by ε-Cu increases the necessary element of hardness, and this helps the inhibition to the softening width of HAZ.Yet when it adds when too much, steel may split in forging process.Therefore, be limited to 5% on it.The Cu amount is preferably 2.0% to 4.0%.
Ni:1.00 to 5%
Ni is by Al-Ni intermetallic compound Ni for example
3The precipitation strength of Al increases the necessary element of hardness, and this helps the inhibition to the softening width of HAZ.In addition, when making up with Cu, Ni is for delaying by the caused hot-work fragility of the excessive interpolation of Cu and to prevent to split in the forging process be effective.Yet when it adds when too much, residual austenite may increase, and under the situation that does not have high-temperature aging to handle, and steel can not be guaranteed the hardness of being scheduled to, and in addition, after thermal treatment, steel may expand.The Ni amount is preferably 1.5% to 4.0%.
Mo:0.5 to 3% and/or (comprise 0%) below the W:2%
Mo and W form M
6C carbide and formation Ni
3The Mo intermetallic compound, and help two kinds of elements of precipitation strength.Yet when Mo and W add when too much, above-mentioned carbide may excessive formation, so that reduce toughness, and in addition, the dimensional change after the thermal treatment (particularly size changing rate difference) may increase.Therefore, limit above-mentioned scope in this article.In the present invention, the Mo composition that is absolutely necessary, and W is an optional elements, but steel can contain them simultaneously.Mo content is preferably 0.5% to 3%, and more preferably 0.7% to 2.5%.W content is preferably below 2%, more preferably below 1.5%.
S:0.10% following (not comprising 0%)
S is the element that can be used for guaranteeing machinability.Yet when it adds when too much, it may cause weld seam to break, so is limited to 0.10% on it.The S amount is preferably below 0.07%, more preferably below 0.05%, also more preferably below 0.025%.
In addition, the present invention must satisfy following condition (1) to (4) { wherein each square brackets [] is represented the content (%) of each element }.
(1)[Cr]×[C]≤3.00
Above-mentioned condition (1) is defined, to delay the formation of thick Cr carbide.When the product of [Cr] and [C] surpassed 3.00, then the dimensional change after the thermal treatment may increase, and the weather resistance possible deviation of surface film.The product of [Cr] and [C] is preferably below 1.80, more preferably below 1.70.For the viewpoint that prevents the dimensional change after thermal treatment, its lower limit is preferably littler.Yet because the viewpoint of the above-mentioned effect of the interpolation of Cr and C, its lower limit is preferably about 0.8 for effectively showing.
(2) [Cu]/[Ni]: 0.5 to 2.2
Above-mentioned condition (2) mainly is defined as being used to utilize the precipitation strength of ε-Cu and being used to suppress the parameter (referring to embodiment given below) that HAZ softens width.In order to show these effects effectively, [Cu] is restricted to 0.5 with the ratio of [Ni].Yet when ratio was too big, it may cause in forging process split.Therefore, be limited to 2.2 on it.Preferably, ratio is 0.7 to 1.5, more preferably 0.85 to 1.2.
(3) [Mo]+0.5 * [W]: 0.5 to 3.0%
As above mentioned, the Mo and the W that constitute above-mentioned condition (3) are the elements that helps precipitation strength.Above-mentioned condition (3) is defined as the parameter that is used for guaranteeing by their precipitation strength hardness, and the softening width of HAZ is suppressed effectively.In above-mentioned condition (3), the coefficient of [W] (0.5) is to consider that the nucleidic mass of Mo is that about 1/2 of W nucleidic mass limits.In order to show these effects effectively, the following of above-mentioned condition (4) is limited to 0.5%.Yet when the amount of Mo and W was too many, above-mentioned carbide may excessively form so that reduce toughness, and in addition, if like this, then the dimensional change after the thermal treatment (particularly size changing rate difference) may increase.Therefore, above-mentioned condition (3) on be limited to 3.0%.Preferably, the following of above-mentioned condition (3) is limited to 1.0%, and more preferably 1.2%; And on the other hand, its upper limit is preferably 2.8%.
(4) [Cu]/[C]: 4.0 to 15
Above-mentioned condition (4) is set up as being mainly used in the peak value that makes the hardness of (after the ageing treatment) after the thermal treatment and moves to the parameter of lesser temps side, and this is the dimensional change inhibition that helps to guarantee after thermal treatment.Usually, it is said that in the dimensional change that ageing treatment (tempering) after causes be (for example, referring to the Fig. 9 that mentions below) that the disappearance (decomposition) by residual austenite in solution treatment (quenching) process is caused; Yet, the inventor has been found that, when as above-mentioned condition (4) in after suitably control has ageing treatment the peak value of hardness move to the lesser temps side effect Cu and during with the mass ratio (ratio of [Cu]/[C]) of the closely-related C of residual austenite, can delay the dimensional change after the thermal treatment significantly.
Fig. 1 shows the figure of ratio [Cu]/[C] to the influence of dimensional change, and wherein size changing rate (mean value and maximum value) is measured according to the method for describing among the embodiment that provides below.In the figure, the data of numbering 44 (steel A) in the table 7 that provides below, 52 (steel C), 56 (steel D), 70 (steel J) and 73 (steel K) have been drawn.These steel contain C, Si, Mn, Cr, Al, Cu, Ni, Mo and the W of content much at one.As in Fig. 8, the ratio of [Cu]/[C] and size changing rate in close relations.As can be seen, by controlling this ratio it is fallen in 4.0 to 15 the scope, can it be fallen in a second aspect of the present invention restricted portion (size changing rate mean value is in ± 0.03% scope, and the size changing rate maximum value is below 0.05%) the controlling dimension velocity of variation.
When the ratio of [Cu]/[C] less than 4.0 the time, the aging temp that hardness reaches peak value is significantly higher than the temperature that residual austenite begins to decompose, therefore the expansion after ageing treatment increases, and on the other hand, when this ratio greater than 15 the time, do not have after the ageing treatment to shrink (having eliminated the expansion after solution heat treatment); In any case, the dimensional change inhibition that all can not obtain to be scheduled in these cases.Above-mentioned ratio is preferably 5.0 to 13, and more preferably 6.0 to 12.
Composition of steel in a second aspect of the present invention is as described in the above, and surplus is iron and unavoidable impurities.Unavoidable impurities is the element that for example may be blended in inevitably in its manufacturing processed in the steel.For example, they comprise P, N and O.The P amount is preferably about below 0.05%, more preferably below 0.03%.The N amount is preferably below about 350ppm, more preferably below the 200ppm, also more preferably below the 150ppm.The O amount is preferably below about 50ppm, more preferably below the 30ppm, also more preferably below the 20ppm.
In the present invention, can add following ingredients to improve other performance of steel.
V:0.5% following (not comprising 0%)
V owing to form carbide for example VC help to increase hardness, and be that the softening width of HAZ is suppressed effective elements.In addition, when handling for example steam nitriding, bath salt nitriding or plasma nitridation by nitriding form diffusion hardened layer on matrix surface, V is for increasing surface hardness and being effective for increasing case depth.In order to show these effects effectively, the V amount is preferably about more than 0.05%.Yet when it adds when too much, the meltage of C may reduce, and the hardness of the martensitic stucture of matrix may descend.Therefore, its upper limit is preferably 0.5%.The V amount is more preferably below 0.4%, also more preferably below 0.30%.
The total amount that is selected from least a element among Ti, Zr, Hf, Ta and the Nb is (not comprise 0%) below 0.5%.
These elements all are nitride forming elements, and these fine dispersion and grain refinings owing to nitride and AlN help toughness to increase.In order to show these effects effectively, preferably, the Ti amount is for about more than 0.01%, and the Zr amount is for about more than 0.02%, and the Hf amount is for about more than 0.04%, and the Ta amount is for about more than 0.04%, and the Nb amount is for about more than 0.02%.Yet when these elements add when too much, the C meltage may reduce, and martensite hardness may reduce.Therefore, the total amount of above-mentioned element is preferably 0.5%.More preferably, the total amount of these elements is below 0.4%, also more preferably below 0.30%.These elements can separately or make up and add.
Co:10% following (not comprising 0%)
Co is to rising Ms point and to improve steel hardness thus to reducing residual austenite be effective elements.In order to show above-mentioned effect effectively, the Co amount is preferably about more than 1%.Yet when it adds when too much, cost may increase.Therefore, its upper limit is preferably 10%.The upper limit of Co amount more preferably 5.5%.
Martensite point (Ms point) 〉=170 ℃
The Ms point
＝550-361×[C]-39×[Mn]-35×[V]-20×[Cr]
-17×[Ni]-10×[Cu]-5×([Mo]+[W])
+15×[Co]+30×[Al]
{ wherein each square brackets [] is represented the content (%) of each element }
In the present invention, the Ms point mainly is the index of the hardness of steel and the dimensional change inhibition after the thermal treatment.When the Ms point was lower than 170 ℃, then residual austenite may increase, and under the situation that does not have high-temperature aging to handle, steel can not have required hardness, and in addition, if like this, then steel may be at the thermal treatment after.The Ms point is preferably higher, more preferably more than 230 ℃, also more preferably more than 235 ℃, also more preferably more than 250 ℃.For the viewpoint of above-mentioned effect, the upper limit that Ms is ordered is not subjected to concrete qualification.Yet, consider and add effect and the effect that above-mentioned element is ordered to set up Ms that its upper limit is preferably about 350 ℃, more preferably 320 ℃.
The method that is used for the mfg. moulding die steel is according to a second aspect of the invention then described.
Manufacture method of the present invention may further comprise the steps: the steel of above-mentioned condition is satisfied in preparation, and under the condition that satisfies following formula (5), described steel carries out solution treatment and ageing treatment:
TA-10≤T2≤TA+10(5)
Wherein,
TA＝0.29×T1-2.63×[Cu]/[C]+225，
T1 represent solid solution temperature (℃), and
T2 represent aging temp (℃).
Particularly, the steel that satisfies above-mentioned condition is prepared into the fusing form, then the steel that is softened (is for example carried out heat forged and annealing, kept 7 hours at about 700 ℃, average rate of cooling with about 17 ℃/hr is cooled to about 400 ℃ in stove then, keeps same cooling afterwards), cut into predetermined shape in rough machined mode afterwards, under the condition of following formula (5), carry out solution heat treatment and ageing treatment then.
As mentioned above, in a second aspect of the present invention, design composition of steel like this and make that the remained austenite content in the solution treatment process is little.In addition, as in following formula (5), when controlling the mass ratio ([Cu]/[C]) of Cu and C relatively with solid solution temperature T1 and aging temp T2, then can control steel, make after ageing treatment, and before the expansion of residual austenite due to decomposing, its hardness can be peak value, so steel can satisfy dimensional change inhibition and hardness after the thermal treatment simultaneously.Usually, the method that is used for the die steel manufacturing is included in the solution treatment under about 950 to 1150 ℃ temperature, and the ageing treatment under about 400 to 530 ℃ temperature provides required hardness to steel thus subsequently.Yet, the inventor confirms by experiment, even in solution treatment in above-mentioned scope and the follow-up ageing treatment, the steel of manufacturing can not have required hardness usually, and can not delay the dimensional change (referring to embodiment given below) after its thermal treatment fully, therefore, the inventor specifically defines above-mentioned formula (5).
The method (the high C high Cr steel of matching convention) of mechanism of the present invention and above-mentioned patent documentation 2 is compared.In patent documentation 2, (Fig. 1 in the corresponding patent documentation 2) as shown in Figure 2, residual austenite when decomposing to a certain degree with the steel tempering, thereby the dimensional change in the tempering can be 0; And in the present invention, steel is also undecomposed residual austenite or the temperature tempering when just having decomposed; And in this, both differ from one another.Particularly, in the present invention, steel almost carries out ageing treatment in the temperature lower than the high C high Cr steel of routine (particularly, almost at about low temperature below 500 ℃).According to the present invention, steel is not to carry out ageing treatment in as the big zone (A in Fig. 3) of the dimensional change after the thermal treatment in patent documentation 2, but ageing treatment is carried out in the zone interior (B in Fig. 3) that can form stable in a large number residual austenite therein, therefore, can think, compare with patent documentation 2, the present invention can make the dimensional change with reduction or the steel of fluctuation.Under such lesser temps steel is being carried out under the situation of ageing treatment, the stability of residual austenite wherein may increase, and residual austenite changes seldom in time, therefore effectively, also reduces steel in time dimensional change after thermal treatment.
About following formula, aging temp T2 is preferably TA ± 5 ℃.
Solid solution temperature T1 can be lower than normally used temperature in die steel is made.Therefore, steel of the present invention not distortion in thermal treatment.Particularly, temperature is preferably in 900 to 1150 ℃ scope.
In the present invention, as in above-mentioned, can suitably controlling solid solution temperature and aging temperature; And specifically do not limit the treatment time.Processing can be implemented under the condition that is generally used for common die steel manufacturing.In brief, the solution treatment time (heat-up time) can be about about 1 to 5 hour, and can to control the ageing treatment time (soaking time) be about about 2 to 8 hours.
Embodiment
With reference to the following example, the present invention is more specifically described, certainly, the present invention is not limited by the examples.On the present invention can reach, mention and the scope of following purpose in, the present invention can suitably be revised and be changed, and any such modification and change all should be in technical scope of the present invention.
The embodiment of a first aspect of the present invention is described below.
Use is at the various steel samples (numbering) shown in table 1 and the table 2.In the vacuum induced melting furnace, the 150kg ingot is prepared into the fusing form, then with it in about 900 to 1150 ℃ of heating, and forge and to be two plates of 400mmT * 750mmW * about 2000mmL.Then, these plates are cooled off gradually with the average rate of cooling of about 60 ℃/hr.After being cooled to the temperature that is not higher than 100 ℃, these plates are heated to about 850 ℃ temperature once more, cool off (annealing) gradually with the average rate of cooling of about 50 ℃/hr then.
Zhi Bei annealing specimen carries out the test of following (1) to (4) in the above described manner.
(1) hardness test (mensuration of highest hardness):
From above-mentioned annealing specimen, cut out the test specimen of the about 20mmT * 20mmW of size * 15mmL, and used as the hardness test specimen.This test specimen is carried out following heat treatment cycle.
Solution heat treatment (quenching): in about 1020 to 1030 ℃ of heating 120 minutes →: at about 400 to 560 ℃ of about 3 hours → naturally cooling of soaking by ventilating cooling → ageing treatment (tempering).
Use Vickers hardness tester (the model AVK of AKASHI is under the load of 5kg) measure as above in about 400 to 560 ℃ scope, change the hardness of the sample of tempering temperature and the highest hardness (HV) of record sample.In the present embodiment, highest hardness is evaluated as well (O) for those of 650HV at least.
(2) dimensional change test (mensuration of the mean value of size changing rate and size changing rate difference):
From above-mentioned annealing specimen, cut out the test specimen that is of a size of about 40mmT * 70mmW * 100mmL, and used as the dimensional change test specimen.With its carry out with above-mentioned (1) hardness test in identical solution treatment, then it is had the temperature tempering of highest hardness.Then, measure " mean value of size changing rate " and " size changing rate difference " in the following manner; And according to the standard of mentioning below, assess sample.Both those qualified samples are because the dimensional change inhibition (acceptance line level) after having excellent thermal treatment is be evaluated as good (O).
(2-1) mensuration of the mean value of size changing rate:
On thickness, width and three directions of length, measure above-mentioned dimensional change test specimen (after annealing, still before solution treatment) and tempered test specimen.Measure thickness difference, width difference and length difference before and after the thermal treatment, and with their mean value (per-cent) as " mean value of size changing rate ".In the present embodiment, " mean value of size changing rate " is fallen into ± within 0.05% those are evaluated as well (O), and will above ± 0.05% those be evaluated as poor (*).
(2-2) mensuration of size changing rate difference:
On thickness, width and three directions of length, measure above-mentioned dimensional change test specimen (after annealing, still before solution treatment) and tempered test specimen.Measure thickness difference, width difference and the length difference of thermal treatment front and back.Among data, with the difference between maximum value and the minimum value (per-cent) as " size changing rate difference ".With the size changing rate difference is that below 0.08% those are evaluated as well (O), and will above 0.08% those be evaluated as poor (*).
(3) welding test (mensuration of the softening width of limit preheating temperature and HAZ):
From above-mentioned annealing specimen, cut out the test specimen that is of a size of about 40mmT * 45mmW * 75mmL, and used as welding piece.With its carry out with above-mentioned (2) dimensional change test in identical solution treatment and temper.
Then, the tempering sample that obtains like this is processed into the plate of Fig. 3 (a).The plate of Fig. 3 (a) has the groove as shown in Fig. 3 (b).Then, use TIG wire rod (Eutectic of Japan " TIG-Tectic 5HSS ", φ 2.4mm) (surplus: iron and unavoidable impurities, unit: quality %), the groove of above-mentioned plate is carried out in the following manner the processing of joint welding with composition shown in the table 3.
Welding conditions:
Electric current: 150A
Voltage: 11V
Welding speed: 9.5 to 14cm/mm
Medium temperature: be not higher than preheating temperature
Heating: 7.1 to 10.4kJ/cm
Preheating: do not have or exist (100 ℃, 200 ℃, 300 ℃ or 400 ℃)
For numbering in the table 2 22 and numbering 23 (both are the simulation steel sample of conventional high C high Cr steel), as among Fig. 4 with welding material buttering on groove surface, to prevent welding influence to matrix component.For buttering, the buttering TIG wire rod of forming shown in using below having (KOBELCO " TGS-50 "), and buttering is the individual layer welding.Welding conditions is same as described above.
The composition of buttering TIG wire rod: 0.09%C-0.93%Si-1.95%Mn-0.009%P-0.01%S (surplus: iron and unavoidable impurities, unit: quality %)
As above-mentioned change preheating condition, measure the minimum temperature (limit preheating temperature) of all not splitting thus at welding metal (DEPO) and HAZ parts.Sample with lower limit preheating temperature more is difficult to split.In the present embodiment, be that below 200 ℃ those are evaluated as well (O) with limit preheating temperature, and will have and be higher than those of 200 ℃ and be evaluated as poor (*).
Carry out Hardness Distribution in the cross section of test specimen of processing of joint welding in order to be determined at above-mentioned limit preheating temperature, with the spacing continuously measured of 1mm from welding fusing line (fusion) position at 1/4 position of plate thickness the sample hardness of the position of 30mm with interval extremely.The distance that welding metal centre portions to hardness is reduced to the position of maximum 600HV is called " HAZ softens width ".For reference, the zone that is used to measure the softening width of HAZ has been shown in above-mentioned Fig. 1.In the present embodiment, be that sample below the 6.5mm is evaluated as at good (O) aspect the repair by welding with the softening width of HAZ; And will be evaluated as poor (*) greater than those of 6.5mm.
(4) toughness test:
Above-mentioned annealing specimen is carried out following heat treatment process.
Solution heat treatment (quenching): in about 1020 to 1030 ℃ of heating 120 minutes →: in about 3 hours of about 400 to 560 ℃ of soaking → cool off or naturally cooling by ventilating by ventilating cooling → ageing treatment (tempering).
Then, in Fig. 5, cut out the test specimen (charpy impact test specimen) that test specimen with 10-mmR V-notch is measured as toughness.This test specimen of test is wherein measured test specimen absorption energy at room temperature in Charpy impact test.Obtain three charpy impact test specimens from a sample, and their data are averaged, as the charpy impact value of sample.In the present embodiment, be that below the 15J those are evaluated as " tenacity excellent " with the charpy impact value.
The result is presented in table 4 and 5.
Table 4 and table 5 have brought following argumentation.
Numbering 1 to 21 in the table 4 is to satisfy the data of the sample number into spectrum 1 to 21 of full terms of the present invention in the table 1.These all have dimensional change inhibition and repair by welding after high rigidity and the excellent thermal treatment, and in addition, these are height toughness and good, and reason is that their limit preheating temperature is below 200 ℃.
Opposite with these is that the numbering 22 to 43 in the table 5 is data of the sample number into spectrum 22 to 43 of any one condition that discontented unabridged version invention limits in the table 2, therefore has following defective.
Numbering 22 and 23 in the table 5 is to be the numbering 22 of the simulation steel sample of conventional high C high Cr steel and 23 data in the table 2.These have the softening width of HAZ of increase and the dimensional change of increase, and reason is that the product of [Cr] and [C] is big and the Ms point is low.When tempering temperature was lower, the hardness increase of these steel was more.Therefore, the tempering temperature of these steel is 510 ℃, and measures its performance.
Numbering 24 in the table 5 is data of the little numbering 24 of the wherein C amount in the table 2.This sample has the hardness of reduction and the softening width of HAZ of increase.
Numbering 25 in the table 5 is that the wherein C in the table 2 measures greatly, the product of [Cr] and [C] is big and the data of the numbering 25 that the Ms point is low.This sample has the dimensional change inhibition after the poor thermal treatment.
Numbering 26 in the table 5 is data of the big numbering 26 of the wherein Si amount in the table 2.Good aspect the mean sizes velocity of variation of this sample after thermal treatment, but its size changing rate difference is big.
Numbering 27 in the table 5 is that the wherein Mn in the table 2 measures the data big and numbering 27 that the Ms point is low.Mean sizes velocity of variation after thermal treatment is big.
Numbering 28 in the table 5 is data of the big numbering 28 of the wherein S amount in the table 2.Limit preheating temperature height and this sample have weld seam disruptive risk.
Numbering 29 in the table 5 is data of the little numbering 29 of the wherein Al amount in the table 2.Low and the softening width increase of HAZ of hardness.
Numbering 30 in the table 5 is data of the big numbering 30 of the wherein Al amount in the table 2.Mean sizes velocity of variation after thermal treatment is so not big, but the size changing rate difference is big.
Numbering 31 in the table 5 is data that the wherein Ni in the table 2 measures little and the numbering 30 that [Cu]/[Ni] ratio is big.Low and the softening width increase of HAZ of this hardness.
Numbering 32 in the table 5 is data of the big numbering 32 of the wherein Ni amount in the table 2.Low and the increase of the mean sizes velocity of variation after thermal treatment of hardness.
Numbering 33 in the table 5 is data that the wherein Cu in the table 2 measures little and the numbering 33 that ratio [Cu]/[Ni] is little.Low and the softening width increase of HAZ of this hardness.
Numbering 34 in the table 5 is data of the numbering 34 of the analog sample of the steel of essentially no Cu in the table 2.In this sample, the Cu amount is 0.05% and is very little, and the ratio of [Cu]/[Ni] is little.Low and the softening width increase of HAZ of hardness.In addition, the mean sizes velocity of variation after thermal treatment increases.
Numbering 35 in the table 5 is data of the numbering 35 of the analog sample of the steel of essentially no Ni in the table 2.In this sample, the Ni amount is 0.05% and is very little, and the ratio of [Cu]/[Ni] is little.Low and the softening width increase of HAZ of hardness.In addition, the mean sizes velocity of variation after thermal treatment increases.
Numbering 36 in the table 5 is data of the numbering 36 of the analog sample of the steel of essentially no Al in the table 2.In this sample, the Al amount is 0.05% and is very little.Low and the softening width increase of HAZ of this hardness.In addition, the mean sizes velocity of variation after thermal treatment increases.
Numbering 37 in the table 5 is that wherein Cu amount and the Ni amount in the table 2 satisfies scope of the present invention, the data of the numbering 37 that the ratio of still [Cu]/[Ni] is little.The softening width of this HAZ increases.
Numbering 38 in the table 5 is data of the little numbering 38 of the wherein Cr amount in the table 2.This hardness is low.
Numbering 39 in the table 5 is data of the big numbering 39 of the wherein Cr amount in the table 2.Dimensional change inhibition after the thermal treatment is poor.
Numbering 40 in the table 5 is data of the little numbering 40 of the total amount of wherein [Mo]+0.5 * [W] in the table 2.Low and the softening width increase of HAZ of hardness.
Numbering 41 in the table 5 is data of the big numbering 41 of the total amount of wherein [Mo]+0.5 * [W] in the table 2.Mean sizes velocity of variation after thermal treatment is so not big, but the size changing rate difference is big.
Numbering 42 in the table 5 is data of the big numbering 42 of the wherein Ti amount in the table 2.Low and the softening width increase of HAZ of hardness.
For reference, the Hardness Distribution curve display of the sample that obtains according to aforesaid method is in Fig. 7.In the accompanying drawings, steel of the present invention (black box) is the numbering 4 in the table 1; And conventional SKD11 steel (black diamonds) is the numbering 22 in the table 2.As in Fig. 7, with the steel comparison of routine, steel of the present invention can prevent softening after welding well.
The embodiment of a second aspect of the present invention is then described.
Use the various steel sample A to K shown in the table 6.In the vacuum induced melting furnace, the 150kg ingot is prepared into the fusing form, then with it in about 900 to 1150 ℃ of heating, and forge and to be two plates of 400mmT * 750mmW * about 2000mmL.Then, these plates are cooled off gradually with the average rate of cooling of about 60 ℃/hr.After being cooled to the temperature that is not higher than 100 ℃, these plates are heated to about 850 ℃ temperature once more, cool off (annealing) gradually with the average rate of cooling of about 50 ℃/hr then.
Zhi Bei annealing specimen carries out the test of following (1) and (2) in the above described manner.
(1) hardness test (mensuration of highest hardness):
From above-mentioned annealing specimen, cut out the test specimen of the about 20mmT * 20mmW of size * 15mmL, and used as the hardness test specimen.It is carried out solution treatment → by the processing of the cooling → ageing treatment of ventilating, leave standstill refrigerative then and process under the condition shown in the table 2.Under each situation, the solution treatment time is about 120 minutes, and aging time is about 3 hours.
After ageing treatment, use Vickers hardness tester (the model AVK of AKASHI is under the load of 5kg) measure sample hardness (HV).In the present embodiment, hardness is evaluated as well (O) for those of 650HV at least.
(2) dimensional change test (the peaked mensuration of the mean value of size changing rate and size changing rate):
From above-mentioned annealing specimen, cut out the test specimen that is of a size of about 40mmT * 70mmW * 100mmL, and used as the dimensional change test specimen.It is carried out solution treatment → by the processing of ventilation fan cooling → ageing treatment, leave standstill cooling then under the condition shown in the table 2.Then, measure " mean value of size changing rate " and " maximum value of size changing rate " in the following manner; And according to the standard of mentioning below, assess sample.Those samples that the both is qualified are because the dimensional change inhibition (acceptance line level) after having excellent thermal treatment is be evaluated as good (O).
(2-1) mensuration of the mean value of size changing rate (mean sizes velocity of variation):
On thickness, width and three directions of length, measure above-mentioned dimensional change test specimen (after annealing, still before solution treatment) and tempered test specimen.Measure thickness difference, width difference and length difference before and after the thermal treatment, and with their mean value (per-cent) as " mean value of size changing rate ".In the present embodiment, " mean value of size changing rate " is fallen into ± within 0.03% those are evaluated as well (O), and will above ± 0.03% those be evaluated as poor (*).
(2-2) mensuration of the maximum value of size changing rate (overall dimension velocity of variation):
On thickness, width and three directions of length, measure above-mentioned dimensional change test specimen (after annealing, still before solution treatment) and tempered test specimen.Measure thickness difference, width difference and the length difference of thermal treatment front and back.In data, with peaked absolute value (per-cent) as " maximum value of size changing rate ".With the overall dimension velocity of variation is that below 0.05% those are evaluated as well (O), and will above 0.05% those be evaluated as poor (*).
(2-3) mensuration of size changing rate difference:
For reference, also be determined at " size changing rate difference " in the description that relates to first aspect present invention.Particularly, on thickness, width and three directions of length, measure above-mentioned dimensional change test specimen (after annealing, still before solution treatment) and tempered test specimen.Measure thickness difference, width difference and the length difference of thermal treatment front and back.In data, with the difference (per-cent) of maximum value and minimum value as " size changing rate difference ".With the size changing rate difference is that below 0.08% those are evaluated as well (O), and will above 0.08% those be evaluated as poor (*).
The result is presented in the table 7.
Table 7
TA
*＝0.29×T1-2.63×[Cu]/[C]+225
Table 7 causes following argumentation.
At first, in the numbering 44 to 47 of table 7, the steel A that its composition of steel of table 6 is satisfied condition of the present invention handles at different solid solution temperature T1 and aging temp T2, and the physicals of analytic sample.
Among these, numbering 44 and numbering 45 are samples of the present invention that aging temp T2 satisfies scope of the present invention (TA ± 10 ℃).The two all has dimensional change inhibition after high rigidity and the excellent thermal treatment (not only aspect the size changing rate difference, and at mean sizes velocity of variation and overall dimension velocity of variation aspect all).
Opposite as these is that numbering 46 is comparative samples that aging temp T2 is higher than the scope of the invention; Numbering 47 is comparative samples that aging temp T2 is lower than the scope of the invention.Both all have soft, and are in addition, although their size changing rate differences after thermal treatment are good, bad aspect mean sizes velocity of variation and overall dimension velocity of variation.
In the numbering 48 to 51 of table 7, the steel B that its composition of steel in the table 6 is satisfied condition of the present invention handles at different solid solution temperature T1 and aging temp T2, and the physicals of analytic sample.
Among these, numbering 48 and numbering 49 are samples of the present invention that aging temp T2 satisfies scope of the present invention (TA ± 10 ℃).The two all has the dimensional change inhibition after high hardness and the excellent thermal treatment.
Opposite with these is that numbering 50 is comparative samples that aging temp T2 is higher than the scope of the invention; Numbering 51 is comparative samples that aging temp T2 is lower than the scope of the invention.Although it is the two size changing rate difference after thermal treatment is good, bad aspect mean sizes velocity of variation and overall dimension velocity of variation.In addition, the hardness of numbering 51 is low.
In the numbering 52 to 55 of table 7, the steel C that its composition of steel in the table 6 is satisfied condition of the present invention handles at different solid solution temperature T1 and aging temp T2, and the physicals of analytic sample.
Among these, numbering 52 and numbering 53 are samples of the present invention that aging temp T2 satisfies scope of the present invention (TA ± 10 ℃).The two all has the dimensional change inhibition after high rigidity and the excellent thermal treatment.
Opposite with these is that numbering 54 is comparative samples that aging temp T2 is higher than the scope of the invention; Numbering 55 is comparative samples that aging temp T2 is lower than the scope of the invention.Hardness is low, and the overall dimension velocity of variation after thermal treatment increases.In addition, the mean sizes velocity of variation of numbering 54 after thermal treatment increases.
In the numbering 56 to 58 of table 7, the steel D that its composition of steel in the table 6 is satisfied condition of the present invention handles at different solid solution temperature T1 and aging temp T2, and the physicals of analytic sample.
Among these, numbering 56 and numbering 57 are samples of the present invention that aging temp T2 satisfies scope of the present invention (TA ± 10 ℃).The two all has the dimensional change inhibition after high rigidity and the excellent thermal treatment.
Opposite with these is that numbering 58 is comparative samples that aging temp T2 is higher than the scope of the invention.Overall dimension velocity of variation after thermal treatment increases.
In the numbering 59 to 61 of table 7, the steel E that its composition of steel in the table 6 is satisfied condition of the present invention handles at different solid solution temperature T1 and aging temp T2, and the physicals of analytic sample.
Among these, numbering 59 and numbering 60 are samples of the present invention that aging temp T2 satisfies scope of the present invention (TA ± 10 ℃).The two all has the dimensional change inhibition after high rigidity and the excellent thermal treatment.
Opposite with these is that numbering 61 is comparative samples that aging temp T2 is higher than the scope of the invention.Good aspect the size changing rate difference of this sample after thermal treatment, but its mean sizes velocity of variation and overall dimension velocity of variation increase.
In the numbering 62 to 64 of table 7, the steel F that its composition of steel in the table 6 is satisfied condition of the present invention handles at different solid solution temperature T1 and aging temp T2, and the physicals of analytic sample.
Among these, numbering 62 and numbering 63 are samples of the present invention that aging temp T2 satisfies scope of the present invention (TA ± 10 ℃).The two all has the dimensional change inhibition after high rigidity and the excellent thermal treatment.
Opposite with these is that numbering 64 is comparative samples that aging temp T2 is higher than the scope of the invention.Good aspect the size changing rate difference of this sample after thermal treatment, but its mean sizes velocity of variation and overall dimension velocity of variation increase.
In the numbering 65 to 67 of table 7, the steel G that its composition of steel in the table 6 is satisfied condition of the present invention handles at different solid solution temperature T1 and aging temp T2, and the physicals of analytic sample.
Among these, numbering 65 and numbering 66 are samples of the present invention that aging temp T2 satisfies scope of the present invention (TA ± 10 ℃).The two all has the dimensional change inhibition after high rigidity and the excellent thermal treatment.
Opposite with these is that numbering 67 is comparative samples that aging temp T2 is higher than the scope of the invention.Good aspect the size changing rate difference of this sample after thermal treatment, but its mean sizes velocity of variation and overall dimension velocity of variation increase.
Following sample (numbering) satisfies the condition of solid solution temperature of the present invention and aging temp, but does not satisfy the condition of composition of steel.Therefore, these comparative samples all have some shortcoming.
Numbering 68 and numbering 69 are the steel H of simulation steel sample of the conventional high C high Cr steel of conduct in the table 6 and two samples of steel I.The product of [Cr] and [C] is big, and [Cu] is little with the ratio of [C], and the Ms point is low.After thermal treatment, mean sizes velocity of variation, overall dimension velocity of variation and size percentage difference all increase.When tempering temperature was lower, the hardness increase of these steel was more.Therefore, the tempering temperature of these steel is 510 ℃, and measures its performance.
Two samples of the steel J that numbering 70 and numbering 71 are that the wherein Cu amount in the table 6 is little, the ratio of the ratio of [Cu]/[Ni] and [Cu]/[C] is all little.Low and the overall dimension velocity of variation increase of hardness.
Numbering 72 and numbering 73 are two samples of the big steel K of the ratio of wherein [Cu]/[C] in the table 6.Both overall dimension velocity of variation increase.
In the present embodiment, there is not the time-dependent manner of display size velocity of variation to change.Yet, when carry out under the condition that steel is being satisfied in requirement of the present invention solution treatment, after carry out man-hour that adds of ageing treatment, then the such sample of handling of expection can keep high rigidity and good dimensional change inhibition, and can delay the time-dependent manner variation of its size changing rate.
Describe the present invention in detail with reference to some specific embodiments; Yet,, be apparent that the present invention can anyly need mode to change and revise with what do not exceed the spirit and scope of the present invention for any technician of this area.
The Japanese patent application (Japanese patent application 2006-294528) that the Japanese patent application (Japanese patent application 2006-283038) that the application submitted to based on October 17th, 2006, on October 30th, 2006 submit to, and the Japanese patent application (Japanese patent application 2007-047490) of submission on February 27th, 2007, and their full content all is attached to this by reference.
All reference of quoting in this article integral body by reference are combined in this.
Industrial usability
According to cold work die steel of the present invention, because as in above-mentioned, suitably controlling alloy Divide, so steel has the change in size inhibition after high rigidity, the excellent heat treatment and has good Repair by welding. Therefore, be conducive to especially by the mould that uses above-mentioned cold work die steel to obtain Be at least about the mould that the steel plate of the height tension of 590MPa is used as tensile strength, and can With further prolongation die life, the particularly life-span after its repair by welding.
In addition, in manufacture method of the present invention, owing to suitably controlling steel-constituent and going back Therefore the suitable condition of control solution treatment and Ageing Treatment can effectively be made and have high rigidity also And the cold work die steel of the change in size inhibition after the excellent heat treatment. Therefore, by according to this The mould that the manufacture method of invention obtains is conducive to be particularly useful as tensile strength and is at least about 590MPa The mould used of the steel plate of height tension, and can further prolong die life, particularly Life-span after its repair by welding.
Claims (12)
1. cold work die steel, described cold work die steel comprise by quality %:
C:0.20 to 0.60%,
Si:0.5 to 2.00%,
Mn:0.1 to 2%,
Cr:3.00 to 9.00%,
Al:0.3 to 2.0%,
Cu:1.00 to 5%,
Ni:1.00 to 5%,
Mo:0.5 to 3%, and/or W:2% following (comprising 0%),
S:0.10% following (not comprising 0%),
Wherein satisfy following condition (1) to (3) { wherein each square brackets [] is meant the content (%) of each element }:
(1)[Cr]×[C]≤3.00，
(2) [Cu]/[Ni]: 0.5 to 2.2,
(3) [Mo]+0.5 * [W]: 0.5 to 3.0%,
And surplus is iron and unavoidable impurities.
2. cold work die steel according to claim 1, described cold work die steel also comprise V:0.5% following (not comprising 0%).
3. it is at least a element among Ti, Zr, Hf, Ta and the Nb of being selected from that (does not comprise 0%) below 0.5% that cold work die steel according to claim 1 and 2, described cold work die steel also comprise total amount.
4. according to each described cold work die steel in the claim 1 to 3, described cold work die steel also comprises Co:10% following (not comprising 0%).
5. according to each described cold work die steel in the claim 1 to 4, described cold work die steel has the martensite point (Ms point) more than 170 ℃, and described martensite point is expressed from the next:
The Ms point
＝550-361×[C]-39×[Mn]-35×[V]-20×[Cr]
-17×[Ni]-10×[Cu]-5×([Mo]+[W])
+15×[Co]+30×[Al]
{ wherein each square brackets [] is represented the content (%) of each element }.
6. one kind is passed through to use the mould that obtains according to each described cold work die steel in the claim 1 to 5.
7. method that is used to make cold work die steel, described method comprises the following steps:
Preparation is satisfied composition according to claim 1 and is satisfied following condition (4) steel of { wherein each square brackets [] is represented the content (%) of each element }:
(4) [Cu]/[C]: 4.0 to 15;
And described steel carried out solution treatment and ageing treatment under the condition that satisfies following formula (5):
TA-10≤T2≤TA+10 (5)
Wherein,
TA＝0.29×T1-2.63×[Cu]/[C]+225，
T1 be meant solid solution temperature (℃), and
T2 be meant aging temp (℃).
8. manufacture method according to claim 7, wherein said steel also comprise V:0.5% following (not comprising 0%).
9. according to claim 7 or 8 described manufacture method, it is at least a element among Ti, Zr, Hf, Ta and the Nb of being selected from that (does not comprise 0%) below 0.5% that wherein said steel also comprises total amount.
10. according to each described manufacture method in the claim 7 to 9, wherein said steel also comprises Co:10% following (not comprising 0%).
11. according to each described manufacture method in the claim 7 to 10, wherein said steel has the martensite point (Ms point) more than 170 ℃, described martensite point is expressed from the next:
The Ms point
＝550-361×[C]-39×[Mn]-35×[V]-20×[Cr]
-17×[Ni]-10×[Cu]-5×([Mo]+[W])
+15×[Co]+30×[Al]
{ wherein each square brackets [] is meant the content (%) of each element }.
12. mould that obtains according to each described manufacture method in the claim 7 to 11.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP283038/2006 | 2006-10-17 | ||
| JP2006283038 | 2006-10-17 | ||
| JP294528/2006 | 2006-10-30 | ||
| JP047490/2007 | 2007-02-27 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN101528962A true CN101528962A (en) | 2009-09-09 |
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| CN102601597A (en) * | 2012-04-01 | 2012-07-25 | 株洲春华实业有限责任公司 | Machining process for railway riveting fastener molds |
| CN103403206A (en) * | 2011-02-21 | 2013-11-20 | 日立金属株式会社 | Cold-work tool steel exhibiting superior machinability |
| CN103403207A (en) * | 2011-02-21 | 2013-11-20 | 日立金属株式会社 | Manufacturing method for cold-working die |
| CN103611805A (en) * | 2013-11-20 | 2014-03-05 | 江苏荣腾精密组件科技股份有限公司 | Punching stretching tool |
| CN104032230A (en) * | 2014-06-13 | 2014-09-10 | 柳城县鼎铭金属制品有限公司 | High-silicon high temperature-resistant corrosion-resistant alloy steel and preparation method thereof |
| TWI468238B (en) * | 2012-08-22 | 2015-01-11 | China Steel Corp | Casting mold and heat-treating method of the same |
| CN104640654A (en) * | 2012-08-20 | 2015-05-20 | 日立金属株式会社 | Method for cutting cold work tool steel, and method for producing cold-working die material |
| CN105586543A (en) * | 2014-10-22 | 2016-05-18 | 镇江忆诺唯记忆合金有限公司 | Heat-resisting alloy steel capable of raising thermal fatigue performance |
| CN107164699A (en) * | 2017-05-13 | 2017-09-15 | 合肥鼎鑫模具有限公司 | A kind of alloy mold and its application for automotive hub die casting |
| CN107937827A (en) * | 2017-11-24 | 2018-04-20 | 攀钢集团攀枝花钢铁研究院有限公司 | Improve the production method of steel polishing performance |
| CN108060364A (en) * | 2017-11-04 | 2018-05-22 | 滁州市新康达金属制品有限公司 | A kind of refrigerator end folding door shell punch forming assembling die and the production line with the mold |
| CN108885067A (en) * | 2016-03-23 | 2018-11-23 | 株式会社神户制钢所 | The manufacturing method of vapor chamber |
| CN109207848A (en) * | 2018-09-04 | 2019-01-15 | 黄石市斯帝金属材料技术开发有限公司 | A kind of universal type die steel |
| CN111607742A (en) * | 2020-05-22 | 2020-09-01 | 广东合一纳米材料科技有限公司 | Novel nano die steel and preparation method thereof |
| CN114250422A (en) * | 2021-12-31 | 2022-03-29 | 安徽哈特三维科技有限公司 | Die steel with good toughness and high thermal conductivity and preparation method thereof |
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2007
- 2007-10-16 CN CNA200780038626XA patent/CN101528962A/en active Pending
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|---|---|---|---|---|
| CN103403207B (en) * | 2011-02-21 | 2016-06-15 | 日立金属株式会社 | The manufacture method of cold working mould |
| CN103403206A (en) * | 2011-02-21 | 2013-11-20 | 日立金属株式会社 | Cold-work tool steel exhibiting superior machinability |
| CN103403207A (en) * | 2011-02-21 | 2013-11-20 | 日立金属株式会社 | Manufacturing method for cold-working die |
| TWI447233B (en) * | 2011-02-21 | 2014-08-01 | Hitachi Metals Ltd | Cold work tool steel having improved machinability |
| CN103403206B (en) * | 2011-02-21 | 2015-11-25 | 日立金属株式会社 | The cold work tool steel of excellent in machinability |
| CN102601597A (en) * | 2012-04-01 | 2012-07-25 | 株洲春华实业有限责任公司 | Machining process for railway riveting fastener molds |
| CN104640654A (en) * | 2012-08-20 | 2015-05-20 | 日立金属株式会社 | Method for cutting cold work tool steel, and method for producing cold-working die material |
| TWI468238B (en) * | 2012-08-22 | 2015-01-11 | China Steel Corp | Casting mold and heat-treating method of the same |
| CN103611805A (en) * | 2013-11-20 | 2014-03-05 | 江苏荣腾精密组件科技股份有限公司 | Punching stretching tool |
| CN104032230A (en) * | 2014-06-13 | 2014-09-10 | 柳城县鼎铭金属制品有限公司 | High-silicon high temperature-resistant corrosion-resistant alloy steel and preparation method thereof |
| CN104032230B (en) * | 2014-06-13 | 2016-08-24 | 柳城县鼎铭金属制品有限公司 | A kind of high silicon corrosion-and high-temp-resistant steel alloy and preparation method thereof |
| CN105586543A (en) * | 2014-10-22 | 2016-05-18 | 镇江忆诺唯记忆合金有限公司 | Heat-resisting alloy steel capable of raising thermal fatigue performance |
| CN108885067A (en) * | 2016-03-23 | 2018-11-23 | 株式会社神户制钢所 | The manufacturing method of vapor chamber |
| CN108885067B (en) * | 2016-03-23 | 2020-08-04 | 株式会社神户制钢所 | Method for manufacturing steam cavity |
| CN107164699A (en) * | 2017-05-13 | 2017-09-15 | 合肥鼎鑫模具有限公司 | A kind of alloy mold and its application for automotive hub die casting |
| CN108060364A (en) * | 2017-11-04 | 2018-05-22 | 滁州市新康达金属制品有限公司 | A kind of refrigerator end folding door shell punch forming assembling die and the production line with the mold |
| CN107937827A (en) * | 2017-11-24 | 2018-04-20 | 攀钢集团攀枝花钢铁研究院有限公司 | Improve the production method of steel polishing performance |
| CN109207848A (en) * | 2018-09-04 | 2019-01-15 | 黄石市斯帝金属材料技术开发有限公司 | A kind of universal type die steel |
| CN111607742A (en) * | 2020-05-22 | 2020-09-01 | 广东合一纳米材料科技有限公司 | Novel nano die steel and preparation method thereof |
| CN114250422A (en) * | 2021-12-31 | 2022-03-29 | 安徽哈特三维科技有限公司 | Die steel with good toughness and high thermal conductivity and preparation method thereof |
| CN114250422B (en) * | 2021-12-31 | 2022-09-30 | 安徽哈特三维科技有限公司 | Die steel with good toughness and high thermal conductivity and preparation method thereof |
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