CN100340691C - Bainite die steel in large section for plastic and preparation method - Google Patents
Bainite die steel in large section for plastic and preparation method Download PDFInfo
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- CN100340691C CN100340691C CNB2004100532813A CN200410053281A CN100340691C CN 100340691 C CN100340691 C CN 100340691C CN B2004100532813 A CNB2004100532813 A CN B2004100532813A CN 200410053281 A CN200410053281 A CN 200410053281A CN 100340691 C CN100340691 C CN 100340691C
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- 229910000521 B alloy Inorganic materials 0.000 description 2
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 2
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- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 2
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Abstract
The present invention relates to a bainite plastic die steel in a large section and a preparing method thereof. The bainite plastic die steel in a large section has the chemical components of the following weight percentage: 0.05 to 0.19 % of C, 0.10 to 0.60 % of Si, 1.0 to 1.65 % of Mn, 0.04 to 0.20 % of V, 1.0 to 1.70 % of Cr, 0.15 to 0.50 % of Mo, at most 0.02 % of P, at most 0.01 % of S, 0 to 0.50 % of Ni, at most 0.01 % of N, 0.005 to 0.025 % of Ti, 0 to 0.0050 % of Ca, 0.01 to 0.04 % of Al and Fe and inevitable impurities as the rest. The method of the present invention takes the components to be processed with converter smelting; the die steel is refined by the method of LF+RH; heat processing is carried out after die casting or continuous casting; the temperature of heat processing and finish rolling (calcining) is above 850 DEG C; after that direct cooling is carried out, and cooling speed is at most 1 DEG C per second; the components are processed with backfire whose temperature is at most 600 DEG C, stress is relieved, and saw cutting cracking is avoided; the purpose that the hardness before and after the backfire is not changed are ensured, so that a large section plate blank having the thickness of 500mm obtains uniform granular bainite structures; a core part does not have martensitic structure formation caused by segregation, and hardness level reaches from 28 to 33 of HRC.
Description
Technical field
The invention belongs to metallurgical technology field, relate to and exempt from the pre-hardened plastic mold steel that quenches, be specially adapted to make large-section plastic mould and manufacture method thereof.
Background technology
The large plastic mould tool thickness that is used for household electrical appliances and automobile at present can reach 500mm, as televisor front and rear covers mould, washing machine mould, air conditioner housing mould and bumper mould etc.Carbon chromium-nickel-molybdenum low-alloy quenched and tempered steel during these moulds use is usually made as German standard, famous DIN2738.The typical chemical ingredients of this steel is as shown in table 1.
The chemical ingredients of the existing large section of table 1 quenching and tempering type plastic die steel, wt%
| The trade mark | C | Si | Mn | Cr | Ni | Mo |
| DIN2738 | 0.38 | 0.25 | 1.50 | 1.80 | 1.0 | 0.20 |
Owing to need carry out modifier treatment, the hardness of this steel is subjected to the influence of cross section different sites cooling rate bigger, causes the large section uniformity of hardness distribution poor.Simultaneously, the hardness of quenched martensite tissue is very sensitive with the variation of tempering temperature, causes thick 400mm cross section hardness maximum disparity to be everlasting more than the 4HRC, and produces and go up uniform distribution of temperature in the restive tempering stove.The ununiformity of this Hardness Distribution causes machinability to be adversely affected.In addition, the large section slab because the section stress that section temperature difference causes is big, the hardening break phenomenon often occurs in quenching process.On cost and operation, on the one hand need add noble alloy elemental nickel about 1% for the hardening capacity that improves the large section slab, make the cost of alloy height.Need to use the tender straight device of large-scale quenching apparatus and template on the other hand, make overall manufacturing cost height, the production cycle is long.
In order to reduce alloy and manufacturing cost, shortening manufacturing cycle, the patent of invention of Chinese patent publication number 98111772.4 discloses the design of alloy of utilizing the non-hardened bainite steel, make thickness reach the 450mm cross section and obtain bainite structure and uniform Hardness Distribution, and the firmness level reaches the lower limit of DIN2738 steel.The carbon content of this steel is more than 0.20%, and manganese content is more than 1.70%, and boron content is 0.0005～0.0050%, to improve the hardening capacity of large section slab.Because carbon, manganese belong to easy segregation alloying element, add that boron content is difficult to factor such as precisely control when smelting, when causing industrial production large section slab (more than the thickness 200mm), the core segregation is serious.And the serious direct result of segregation is exactly, even slab core air cooling after hot-work has also obtained martensitic stucture.Though by follow-up tempering, core has obtained the tempered sorbite tissue, still have gap after its hardness and the bainite structure tempering.Because core is different with other position tissue, machinability is adversely affected.Therefore, though this patent of invention has successfully adopted the composition design of non-hardened bainite steel to produce thin specification slab, be difficult to produce the above large section slab of high-quality thick 200mm.
Summary of the invention
The object of the present invention is to provide a kind of bainite large-section plastic mould steel and manufacture method thereof, large section slab uniformity of hardness distribution is better.
For the technology that solves existing quenched and tempered steel and the weakness on the cost, avoid the segregation of carbon manganese and the boron content of existing non-hardened and tempered steel patent of invention to be difficult to the core martensitic stucture phenomenon that precisely control brings simultaneously, the present invention intends formerly adopting low-carbon (LC) on the patent basis, falling manganese, go the boron alloy technology, add a small amount of multicomponent alloy element scheme such as suitable chromium, molybdenum and vanadium simultaneously, obtain bainite structure.Be to adopt low-carbon (LC) (＜0.20%), middle manganese (＜1.70%) adopts the matching Design of alloying elements such as chromium, molybdenum, vanadium simultaneously to reduce the segregation tendency, and matches with suitable production technique, guarantees to obtain the granular bainite tissue after the hot-work.Air cooling imposes and is not higher than 600 ℃ of tempering after hot-work, and the large section slab that makes thickness reach 500mm obtains uniform bainite structure, and the martensitic stucture that the core segregation-free causes forms.Because steel of the present invention is when tempering below 600 ℃, along with variation of temperature hardness remaining unchanged substantially, therefore on acquisition and the equal firmness level's of existing quenched and tempered steel basis.
Technical scheme of the present invention, its chemical ingredients following (weight %): C 0.05～0.19%, Si0.10～0.60%, Mn 1.0～1.65%, V 0.04～0.20%, and Cr 1.0～1.70%, Mo0.15～0.50%, ≤ 0.02%P, S≤0.01%, Ni 0.10～0.50%, and Ti 0.005～0.025%, Al 0.01～0.04%, and all the other are Fe and unavoidable impurities.
Its preferred component following (weight %):
C 0.10～0.15%, and Si 0.15～0.40%, and Mn 1.45～1.65%, V 0.04～0.10%, Cr 1.20～1.60%, and Mo 0.25～0.40%, P≤0.02%, S≤0.01%, Ni 0.10～0.50%,, Ti 0.01～0.025%, Al 0.01～0.04%, and all the other are Fe and unavoidable impurities.
Further, the present invention also comprises Ca 0～0.0050%, N≤0.01%.
C:0.05～0.19% is to guarantee that acquisition granular bainite tissue and hardness are the important element of HRC28～33.Too low, can not guarantee to obtain granular bainite tissue and the needed hardness of steel.Too high, can cause the slab center segregation serious, form the core martensitic stucture.
Si:0.10～0.60%, suitably silicone content can help deoxidation, and forms silicate together with calcium aluminium, helps to improve machinability.But too high silicone content can improve martensite hardening capacity, forms the core martensitic stucture.
Mn:1.00～1.65% is that acquisition granular bainite tissue and hardness are the important alloying element of HRC28～33.Too low, be difficult to guarantee that the large section slab all obtains granular bainite tissue and above-mentioned hardness.Too high, can cause the slab center segregation serious, form the core martensitic stucture.
V:0.04～0.20% adds V and helps obtaining flat bainitic transformation curve, thereby assurance tissue and hardness are not cooled off velocity variations and changed.In addition, utilize V forging/rolling the back and from ferrite, separate out carbonitride, to improve the hardness and the intensity of steel.But V＞0.20% will seriously reduce the plasticity and the toughness of steel.
Cr:1.0～1.7% adds chromium, can improve the hardness of steel on the one hand, can improve the corrosion resistance nature of steel on the other hand.In addition, chromium also is that bainitic transformation promotes element.But too high chromium and manganese add in the steel simultaneously, can cause low melting point Cr-Mn composite oxides to form, and form surface crack in hot procedure.
Mo:0.15～0.50% promotes bainitic transformation strongly, and guarantees flat bainitic transformation curve, helps the large section slab to obtain uniform tissue and Hardness Distribution.But when molybdenum content greater than 0.50% the time, can form alloy carbide, influenced promoter action to bainitic transformation.
Ti:0.005～0.025%, little titanium are handled and are stoped growing up of crystal grain that obvious help is arranged in heat-processed for the steel of not implementing follow-up quench treatment.Simultaneously, can avoid low melting point Cr-Mn composite oxides to form, prevent that surface crack from producing high chromium steel.But its content can not be too high, and not so the TiN particle is thick, not only can not stop grain growth, and can damage the machinability of steel.
Ca:0～0.0050%, calcium is handled can control oxide morphology, and compound by oxide compound-sulfide, can improve machinability.
N :≤0.01%, belong to control element, not so can form aluminium nitride together with aluminium, the hot workability of steel is worsened.
Al:0.01～0.04%, suitably aluminium content can help deoxidation, and forms silicate together with calcium, silicon, helps to improve machinability.In addition, because the oxidation capacity of aluminium is stronger than chromium, its adding can avoid low melting point Cr-Mn composite oxides to form, and prevents that surface crack from producing.But too high aluminium content can form aluminium nitride, and the hot workability of steel is worsened.
Ni:0.10～0.50%, suitable nickel content can promote the granular bainite structural transformation, and improves the toughness of steel, but too high nickel content can increase cost of alloy.
P :≤0.02% and S :≤0.01%, reduce this two impurity content, to reduce segregation as far as possible.
The manufacture method of bainite large-section plastic mould steel of the present invention comprises the steps,
Press mentioned component and smelt, reach LF+RH refining die steel, LF desulfurization, alloying, the RH dehydrogenation is to remove inclusion and obnoxious flavour, particularly hydrogen;
Adopt die casting or continuous casting mode to pour into a mould;
Hot-work after the cast requires 1250～1300 ℃ of control steel ingot soaking temperatures, 1200～1280 ℃ of continuously cast bloom soaking temperatures;
Control hot-work (rolling or forging), finish to gauge (forging) temperature is more than 850 ℃;
Directly cooling after the hot-work, speed of cooling is not higher than 1 ℃/s; Whole slab cross section can obtain the granular bainite tissue, and core can not occur because the martensitic stucture that segregation causes simultaneously;
Impose again and be not higher than 600 ℃ of tempering, eliminate stress, avoid the sawing cracking, and hardness does not change before and after guaranteeing tempering, the large section slab that makes thickness reach 500mm obtains uniform granular bainite tissue, and the martensitic stucture that the core segregation-free causes forms the firmness level and reaches HRC28～33.
Beneficial effect of the present invention
The present invention adopts low-carbon (LC), falls manganese, goes the boron alloy technology, adds a small amount of multicomponent alloy element scheme such as suitable chromium, molybdenum and vanadium simultaneously, obtains bainite structure.Be to intend adopting low-carbon (LC) (＜0.20%), middle manganese (＜1.70%) adopts the matching Design of alloying elements such as chromium, molybdenum, vanadium simultaneously to reduce the segregation tendency, and matches with suitable production technique, guarantees to obtain the granular bainite tissue after the hot-work.Air cooling imposes and is not higher than 600 ℃ of tempering after hot-work, and the large section slab that makes thickness reach 500mm obtains uniform bainite structure, and the martensitic stucture that the core segregation-free causes forms.Because steel of the present invention is when tempering below 600 ℃, along with variation of temperature hardness remaining unchanged substantially, therefore on acquisition and the equal firmness level's of existing quenched and tempered steel basis, large section slab uniformity of hardness distribution is better.
Description of drawings
Fig. 1 a, b are the CCT curve of the present invention and Comparative Examples example 2 non-hardened and tempered steels (CN98111772.4).
Fig. 2 is that rate of cooling is to steel of the present invention and Comparative Examples 2 bainitic transformation Temperature Influence.
Fig. 3 is that rate of cooling is to steel of the present invention and Comparative Examples 2 non-hardened and tempered steels.
Fig. 4 a～Fig. 4 e shows plate slab of the present invention cross section Hardness Distribution.
Fig. 4 f, Fig. 4 g show two Comparative Examples steel 400mm heavy slab cross section Hardness Distribution.
The granular bainite that steel 500mm heavy slab of the present invention shown in Figure 5 obtains is organized synoptic diagram.
Embodiment
According to above-mentioned design of alloy thinking, smelted 5 stove steel in testing laboratory, be cast into the 100kg steel ingot, its chemical ingredients is as shown in table 2.For relatively, show the composition of Comparative Examples 1 quenched and tempered steel DIN2738 and industrial Comparative Examples 2 non-hardened and tempered steels (CN98111772.4) simultaneously.Mandatory declaration be when industrial production Comparative Examples 2 non-hardened and tempered steels (CN98111772.4), to have added small additions of chromium and nickel to contrasting quenched and tempered steel DIN2738 level in order to improve slab hardness.150 * 300mm sample is processed in the steel ingot forging, carries out air cooling and sand cooling respectively to room temperature.Whole section parts intercepting metallographic sample to the test slab carries out structure observation and measurement of hardness.Why dividing air cooling and sand cooling, mainly is to investigate the susceptibility of the hardness of designed steel to rate of cooling.Metallographic structure is observed and is shown that all example steel have all obtained the granular bainite tissue under two kinds of cooling conditionss.Hardness test result shows that the whole cross section of test steel has all obtained basic equal hardness (HRC28～33) under two kinds of cooling conditionss, as shown in table 3.
In order to study the structural transformation characteristics of steel of the present invention after hot-work, on hot modeling test machine, measured its dynamic CCT curve.1200 ℃ * 10min of soaking temperature is cooled to 1100 ℃ and imposes 0.20 strain, is cooled to 1050 ℃ again and imposes 0.30 strain, is cooled to room temperature with different cooling rate again, tissues observed, and measure hardness.The CCT curve that obtains as shown in Figure 1a.In order to compare, Fig. 1 b shows the CCT curve of Comparative Examples 2 non-hardened and tempered steels (CN98111772.4) of industrial interpolation chromium and nickel.
The chemical ingredients of table 2 the present invention and Comparative Examples steel, wt%
The hardness of table 3 example steel under air cooling and sand cooling condition, HRC
| Embodiment | Carbon equivalent Ceq=C+Mn/6+ (Cr+Mo+V)/5+ (Cu+Ni)/15 | Air cooling hardness HRC | Sand |
| 1 | 0.754 | 30 | 29 |
| 2 | 0.732 | 29 | 28 |
| 3 | 0.738 | 29 | 29 |
| 4 | 0.743 | 30 | 29 |
| 5 | 0.771 | 33 | 32 |
The bainite of steel of the present invention begins transformation temperature and changes very little in cooling rate＜5 ℃/s scope, it is 500～510 ℃, (＜0.5 ℃/s) change in the scope very for a short time is 490～510 ℃, as shown in Figure 2 and Comparative Examples 2 non-hardened and tempered steels (CN98111772.4) are only in very narrow cooling rate.In addition, Comparative Examples 2 non-hardened and tempered steels (CN98111772.4) martensite hardening capacity height, the critical cooling rate that promptly obtains martensitic stucture is 3 ℃/s, less than steel of the present invention obtain martensitic stucture critical cooling rate (7 ℃/s).The tendency of this explanation steel formation of the present invention martensitic stucture is more much smaller than Comparative Examples 2 non-hardened and tempered steels.
The hardness of the hardness of steel of the present invention and Comparative Examples 2 non-hardened and tempered steels rate of cooling less than 0.5 ℃/s scope in quite, be VHN315～345 (HRC30～34), reached the level of quenched and tempered steel DIN2738.But along with the further rising of rate of cooling, the degree that steel hardness of the present invention increases is much smaller than Comparative Examples 2 non-hardened and tempered steels, as shown in Figure 3.Test-results shows that the tissue of steel of the present invention and hardness are lower than non-example 2 quenched and tempered steel to the susceptibility comparison of rate of cooling.
Smelt and thermal analogy work according to mentioned component principle of design and testing laboratory's port, carried out industrialness trial-production.Production Flow Chart is: converter smelting, LF+RH refining, die casting, is rolled back spiral-plate air cooling at steel ingot soaking, breaking down, is being no more than tempering under 600 ℃ of temperature then.The test slab thickness is 100,200,300,400 and 500mm, and its chemical ingredients is as shown in table 4.Analyzed the Hardness Distribution of slab, shown in Fig. 4 a～Fig. 4 e in whole cross section.Fig. 4 f and Fig. 4 g show two Comparative Examples steel 400mm heavy slab cross section Hardness Distribution.
The chemical ingredients of table 4 steel of the present invention, wt%
| C | Si | Mn | P | S | V | Cr | Ni | Mo | Al | Ti | N |
| 0.125 | 0.295 | 1.55 | 0.015 | 0.0035 | 0.05 | 1.45 | 0.20 | 0.30 | 0.031 | 0.020 | 0.0065 |
As seen from the figure, with the steel of producing with a kind of composition of the present invention, when slab thickness changes to 500mm from 100mm, its hardness is all in HRC28～33 scopes of design, and the gap of the average hardness of heavy slab and thin slab is in 3HRC, and the hardness maximum disparity of same block of slab also is controlled in the 3HRC.This fully shows the hardness advantage low to the susceptibility of rate of cooling of steel of the present invention.
More same thickness (400mm) slab, the maximum disparity of steel Hardness Distribution of the present invention is 3HRC, Comparative Examples 1 modified DIN2738 steel is because the core hardness highest hardness gap that causes on the low side is 5HRC, and Comparative Examples 2 non-hardened and tempered steels (CN98111772.4) are because the higher highest hardness gap that causes of core hardness also is 5HRC.This explanation, better with the large section slab uniformity of hardness distribution that steel of the present invention is produced than two kinds of compared steel.
Structure observation shows, the large section that reaches 500mm with the thickness of steel production of the present invention has obtained uniform granular bainite tissue, as shown in Figure 5.Slab core does not find because the martensitic stucture that causes of segregation, and these are different with Comparative Examples 2 non-hardened and tempered steels.
Plastic die steel in use unavoidably contacts with atmosphere or humid atmosphere, and occurs point corrosion easily, and this will influence the surface quality of die surface glossiness and plastics.Generally speaking, the corrosion-resistant ability of steel can be represented with chromium equivalent Cr (eq)=Cr+3.3Mo+0.5Ni.The calculation result of carrying out according to the chemical ingredients of table 3 shows that the chromium equivalent of steel of the present invention is 2.49, is lower than 2.94 of the modified DIN2738 steel of contrast slightly, but apparently higher than 1.48 of Comparative Examples 2 non-hardened and tempered steels.Though the corrosion-resistant ability of this indication steel of the present invention is lower slightly than Comparative Examples 1 modified DIN2738 steel, far above Comparative Examples 2 non-hardened and tempered steels.
Can find that by the foregoing description and effect analysis steel comparison of the present invention is better than the uniformity of hardness distribution of the large section slab that modified DIN2738 steel is made, corrosion resistance is approaching.Steel of the present invention has reduced the nickel content of half at least, and do not need quench treatment, simultaneously, when tempering temperature below 600 ℃ the time, the hardness of steel of the present invention does not change along with temperature fluctuation, compared steel is then different, and significant changes in hardness takes place along with the variation of tempering temperature its martensitic stucture that forms in quenching process.Therefore, steel comparison of the present invention is lower than the cost of alloy and the manufacturing cost of modified DIN2738 steel, and manufacturing process is simpler, the manufacturing cycle is shorter, and environmental pollution is littler.
Steel of the present invention and and the common feature of Comparative Examples 2 non-hardened and tempered steels (CN98111772.4) be all to have removed quenching process from.Both cost of alloy are near (content of vanadium of steel of the present invention has only half of compared steel), and manufacturing cost is also approaching.Great advantage is that steel uniformity of hardness distribution of the present invention is better than Comparative Examples 2 non-hardened and tempered steels.This is with the latter higher carbon and manganese content, adds to be difficult to accurately control by boron when smelting to cause large section slab core segregation martensitic stucture seriously to occur relevant.Second advantage be, steel of the present invention chromium content higher, whole chromium equivalent is also obviously high, its corrosion resistance is than Comparative Examples 2 non-hardened and tempered steel height.The 3rd advantage is that the thick titanium nitride inclusion that the large section slab core made from steel of the present invention occurs is few more than Comparative Examples 2 non-hardened and tempered steels.This is because in order to guarantee the main solid solution of boron in Comparative Examples 2 non-hardened and tempered steels in matrix, the titanium content of interpolation is Ti/N=3～4, with fixed nitrogen, not so can cause boron nitride to occur, and influences the promoter action of boron to bainitic transformation.But can cause Comparative Examples 2 non-hardened and tempered steel slab cores thick titanium nitride inclusion to occur like this, thereby machinability is had disadvantageous effect.And the titanium content of steel of the present invention is according to Ti/N=3～4 design, and its high titanium content is no more than 0.025%.At last, draw point of the present invention has proposed the aluminium content requirement to the characteristics of Gao Ge (about 1.40%) Gao Meng (about 1.50%) alloying constituent, and purpose is the steel slab surface crackle that low melting point Cr-Mn oxide inclusion causes when avoiding making steel.This is confirmed in actual industrial production, also is of the present invention one big innovation part.
The cost of alloy of steel of the present invention is low, and the segregation tendency is little, does not need quench treatment, and air cooling after the hot-work imposes tempering again, just can make thickness reach the 500mm slab and obtain hardness HRC28～33.Heavy in section tissue and Hardness Distribution are even, and certain corrosion resistance is arranged.Its manufacturing process is simple, cost is low, the cycle is short.Therefore, steel of the present invention is specially adapted to make the uniform large-section plastic mould of hardness.
Since the invention process, nearly 10000 tons of steel have been produced, thickness range is from 35～500mm, Hardness Distribution is even, machinability is good, obtained household electrical appliances and automobile plastic mould user's favor, progressively modified DIN2311 of substituting import one and DIN2738 steel have obtained good economic benefit.Simultaneously, also be that country saves foreign exchange, reduce Chinese mould user's material cost and brought good social benefit.
Claims (7)
1. bainite large-section plastic mould steel, chemical ingredients is as follows: below be weight percentage,
C 0.05～0.19％，
Si 0.10～0.60％，
Mn 1.0～1.65％，
V 0.04～0.20％，
Cr 1.0～1.70％，
Mo 0.15～0.50％，
P ≤0.02％，
S ≤0.01％，
Ni 0.10～0.50％，
Ti 0.005～0.025％，
Al 0.01～0.04％，
All the other are Fe and unavoidable impurities.
2. bainite large-section plastic mould steel as claimed in claim 1 is characterized in that, chemical ingredients is: C 0.10～0.15%, Si 0.15～0.40%, and Mn 1.45～1.65%, and V 0.04～0.10%, Cr 1.20～1.60%, Mo 0.25～0.40%, P≤0.02%, S≤0.01%, Ni 0.10～0.50%, Ti 0.01～0.025%, and Al 0.01～0.04%, and all the other are Fe and unavoidable impurities.
3. bainite large-section plastic mould steel as claimed in claim 1 or 2 is characterized in that, also comprises N≤0.01%, and Ca 0～0.0050%.
4. the manufacture method of a bainite large-section plastic mould steel is characterized in that, comprises the steps, its composition: C 0.05～0.19%, Si 0.10～0.60%, and Mn 1.0～1.65%, V 0.04～0.20%, and Cr 1.0～1.70%, and Mo 0.15～0.50%, P≤0.02%, S≤0.01%, Ni 0.10～0.50%, N≤0.01%, Ti 0.005～0.025%, and Ca 0～0.0050%, Al 0.01～0.04%, and all the other are Fe and unavoidable impurities;
Press mentioned component and smelt RH vacuum outgas then;
Die casting or continuous casting, control steel ingot soaking temperature is 1250～1300 ℃, the continuously cast bloom soaking temperature is 1200～1280 ℃;
Control hot-work, finish to gauge or final forging temperature are more than 850 ℃;
Directly cooling after the hot-work, speed of cooling is not higher than 1 ℃/s;
Impose and be not higher than 600 ℃ of tempering, the large section slab that makes thickness reach 500mm obtains
Uniform granular bainite tissue, the martensitic stucture that the core segregation-free causes forms.
5. the manufacture method of bainite large-section plastic mould steel as claimed in claim 4 is characterized in that, smelts and adopts converter smelting.
6. the manufacture method of bainite large-section plastic mould steel as claimed in claim 4 is characterized in that, carries out the LF refining before the RH vacuum outgas.
7. the manufacture method of bainite large-section plastic mould steel as claimed in claim 4 is characterized in that, air cooling or sand cooling are adopted in described cooling.
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| BRPI0901378A2 (en) * | 2009-04-03 | 2010-12-21 | Villares Metals Sa | baintically mold steel |
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| CN101956136B (en) * | 2010-11-01 | 2012-06-27 | 机械科学研究总院先进制造技术研究中心 | Martensite-granular bainite plastic die steel and manufacturing method thereof |
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