CN101072891A - Low carbon free cutting steel - Google Patents
Low carbon free cutting steel Download PDFInfo
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- CN101072891A CN101072891A CNA2005800417131A CN200580041713A CN101072891A CN 101072891 A CN101072891 A CN 101072891A CN A2005800417131 A CNA2005800417131 A CN A2005800417131A CN 200580041713 A CN200580041713 A CN 200580041713A CN 101072891 A CN101072891 A CN 101072891A
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
Abstract
A low carbon free-cutting steel which has a chemical composition that C: 0.03 to 0.19 %, Si = 0.10 %, Mn: 1.00 to 2.50 %, P: 0.01 to 0.12 %, S: 0.26 to 0.63 %, Al = 0.010 %, N: 0.0030 to 0.0250 %, O: 0.005 to 0.035 %, Te: 0.002 to 0.100 % and the balance: Fe and impurities, and satisfies (Mn/S) = 4.0. The above steel may contain one or more of 0.04 to 1.25 % of Cr, 0.04 to 0.60 % of Ni and 0.04 to 0.40 % of Mo. The above steel is ''a free-cutting steel being friendly to the environment of the earth'' since it is free of Pb, and, nevertheless, exhibits the machinability superior to that of a conventional Pb free-cutting steel, and further, exhibits the hot workability better than that of conventional Bi free-cutting steel, is free from the occurrence of a crack or scab, and is excellent in productivity, and thus can be suitably used as a raw material of soft small parts which do not need high strength.
Description
Technical field
The present invention relates to low carbon free cutting steel, relate to a kind of low carbon free cutting steel of productivity excellence in more detail, although it does not contain Pb (lead) and Bi (bismuth), have more good machinability compared with existing P b quick-tuming steel, and hot workability is also more good than existing Bi quick-tuming steel.
Background technology
Always, former material as the soft finding that not too needs intensity, improved machinability for productivity improves, what mainly use is this low carbon free cutting steel that is prescribed as " the compound quick-tuming steel steel of sulphur and sulphur " in JIS G 4804 (1999) of SUM11, SUM12, SUM22, SUM23, SUM25, SUM31, SUM32, SUM22L～SUM24L and SUM31L.
Yet the requirement from industrial community is that the quick-tuming steel of more excellent machinability is arranged than above-mentioned low carbon free cutting steel.
Compound interpolation S, Te, Pb and Bi " quick-tuming steel " therefore, for example proposed in patent documentation 1.
On the other hand, because in recent years to the attention of global environment problem, for the quick-tuming steel of the content that has reduced Pb with not contain the expectation of quick-tuming steel of Pb fully very big.
Therefore, propose to have in patent documentation 2 a kind of " low-carbon (LC) sulphur is quick-tuming steel ", it is the P of compound interpolation 0.02～0.40 quality % and surpasses 0.4 and the S below 1.0 quality %, and the content of Pb is suppressed at is lower than 0.01 quality %.
In patent documentation 3, proposing has a kind of compound a large amount of S of 0.4～1.0 quality % and Sn of 0.0015～0.60 quality % of having added, and does not contain " low-carbon sulphur free-cutting steel " of Pb.
Proposed a kind of " low-carbon (LC) sulphur is the quick-tuming steel wire rod " in patent documentation 4, it is compound to have added the P of 0.05～0.20 quality % and the S of 0.15～0.50 quality %, and has controlled the yield tensile ratio of the width average and the wire rod of sulfide-based inclusion.Also have, in this patent documentation 4, also propose to contain " low-carbon (LC) sulphur is the quick-tuming steel wire rod " more than a kind of Bi, Pb and Te for machinability improves.
Proposed a kind of " quick-tuming steel " in patent documentation 5, its compound P of 0.05～0.2 quality % and S of 0.16～0.5 quality % of having added controls the mean sizes of MnS inclusion simultaneously, and is to form by continuous casting manufacturing with certain conditions.Also have, in this patent documentation 5, also propose to contain " quick-tuming steel " more than a kind of Bi, Pb and Te in order to improve machinability.
A kind of " low-carbon (LC) sulphur is the manufacture method of quick-tuming steel " proposed in patent documentation 6 in addition, this method is to pass through Continuous casting process, make in mass, with C:0.05～0.15%, Mn:0.5～2.0%, S:0.1～0.4%, P:0.05～0.10% and N:0.0020～0.0150% is the low-carbon sulphur free-cutting steel of basal component, and in described basal component, contain Pb, Bi, among the Te more than at least a kind, when counting 0.01～0.40% low-carbon (LC) sulphur and be compound quick-tuming steel with their total quality, employing contains the deoxidation material of Si, with converter the molten steel that has carried out Decarburising and refining is carried out after the deoxidation, carry out C, Mn, P, S, the composition adjustment of N etc., and the oxidisability (FetO+MgO%) of ladle slag adjusted to below the 25 quality %, add Pb then as required, Bi, Te, and molten steel oxygen amount is in 0.01～0.015 quality %, and makes Si content be in 0.003～0.08 quality % and cast continuously.
[patent documentation 1] spy opens clear 59-205453 communique
[patent documentation 2] spy opens the 2000-319753 communique
[patent documentation 3] spy opens the 2002-249848 communique
[patent documentation 4] spy opens the 2003-253390 communique
[patent documentation 5] spy opens clear 62-149854 communique
[patent documentation 6] spy opens flat 7-305110 communique
By aforesaid patent documentation 1 disclosed " quick-tuming steel ", compare with SUM11, SUM12, SUM22, SUM23, SUM25, SUM31, SUM32, SUM22L～SUM24L and SUM31L as conduct " the compound quick-tuming steel steel of sulphur and sulphur " regulation among the JIS G 4804 (1999), though excellent in machinability, but therefore the only compound steel that adds S, Te, Pb and Bi may not necessarily access stable excellent hot workability.When containing Pb, can not say so in addition " quick-tuming steel useful " to global environment.
By patent documentation 2 disclosed " low-carbon (LC) sulphur is quick-tuming steel ",, still contain Pb though suppress the content of Pb to such an extent that be lower than 0.01 quality %.Because the only compound P that has added 0.02～0.40 quality % and surpass 0.4, the S below 1.0 quality %, so its machinability ratio existing P b quick-tuming steel is poor.
By patent documentation 3 disclosed " low-carbon sulphur free-cutting steel ", because only compoundly added a large amount of S of 0.4～1.0 quality % and the Sn of 0.0015～0.60 quality %, so its machinability ratio existing P b quick-tuming steel is poor.In addition, owing to contain a large amount of S, may not necessarily access stable excellent hot workability.
Do not contain among by patent documentation 4 disclosed " low-carbon (LC) sulphur is the quick-tuming steel wire rod " Bi, Pb and Te any one, its machinability ratio existing P b quick-tuming steel is poor.On the other hand, among above-mentioned " low-carbon (LC) sulphur is the quick-tuming steel wire rod ",, may not necessarily access stable and excellent hot workability though contain the excellent in machinability more than a kind of Bi, Pb and Te.
By do not contain among the patent documentation 5 disclosed " quick-tuming steel " Bi, Pb and Te any one, its machinability ratio existing P b quick-tuming steel is poor.On the other hand, among above-mentioned " quick-tuming steel ",, may not necessarily access stable and excellent hot workability though contain the excellent in machinability more than a kind of Bi, Pb and Te.
By patent documentation 6 disclosed " low-carbon (LC) sulphur is quick-tuming steel " in its basal component, do not contain yet Bi, Pb and Te any one, its machinability ratio existing P b quick-tuming steel is poor.On the other hand, above-mentioned " low-carbon (LC) sulphur is quick-tuming steel " contains more than a kind of Bi, Pb and Te, counts 0.01～0.40 quality % with their total content, though its excellent in machinability may not necessarily access stable and excellent hot workability.
Summary of the invention
The objective of the invention is to, although a kind of Pb and Bi of not containing is provided, but still have than the more good machinability of existing P b quick-tuming steel, and hot workability is better than existing Bi quick-tuming steel, thereby can not crack and peel off the low carbon free cutting steel of the productivity excellence of flaw, comprise also that wherein low-carbon (LC) sulphur is quick-tuming steel.
Present inventors study with regard to following problem: for " quick-tuming steel " that obtains can using as not containing " quick-tuming steel useful to global environment " of Pb, the extension of the MnS that brings by the processing under suppressing to be heated, the long-width ratio (" length/width ") of MnS in the steel after the hot-work is maintained smaller value, thereby the Te that can improve machinability adds steel.
Promptly, because contain Te and Pb, so its ductility under being heated is low, though therefore hot workability is poor, therefore but have good machinability,, adopt on a small quantity but " the compound quick-tuming steel of S-Pb-Te " that use all the time as quick-tuming steel, " the compound quick-tuming steel of S-Te " with removed " Pb " from this steel carries out melting and investigates hot workability it.
Its result obtains following (a) and reaches (b).
(a) from " the compound quick-tuming steel of S-Pb-Te ", removed the same with Te known be " the compound quick-tuming steel of S-Te " that makes the elements Pb that hot workability reduces, its ductility ratio " the compound quick-tuming steel of S-Pb-Te " under being heated is low on the contrary, crackle takes place easily and peel off flaw.
(b) " the compound quick-tuming steel of S-Te " ductility under being heated reduces along with the increase of the content of Te, crackle takes place easily and peel off problem in the hot-work such as flaw.
Therefore, next melting various " the compound quick-tuming steels of S-Te ", the influence that probe composition element brings hot workability and machinability.Its result obtains the conclusion of following (c)～(e).
(c) in " the compound quick-tuming steel of S-Te ", in order to improve hot workability, the generation that suppresses crackle and peel off flaw need make Mn amount contained in the steel measure (i.e. the value of " Mn/S ") at least more than 4.0 with respect to S.
(d) if " the compound quick-tuming steel of S-Te " after the hot-work implemented Wire Drawing, show as Fig. 1 medelling ground further break owing to have the MnS of smaller long-width ratio, become long-width ratio littler near granulous MnS, the situation that has machinability very to improve.On the other hand, the situation of existing P b quick-tuming steel of not adding Te shown in Fig. 2 medelling, the shape of the MnS of having been cut apart and granularly differ quite far away.
(e) for by to " the compound quick-tuming steel of S-Te " after hot-work enforcement Wire Drawing, make MnS fracture spheroidizing and improve machinability, make the content of Te and Mn satisfy specific relation, control chemical constitution in this way and get final product.
The present invention is based on above-mentioned conclusion and finish, it will be intended to the low carbon free cutting steel shown in following (1)～(4).
(1) a kind of low carbon free cutting steel, wherein, in quality %, contain that C:0.03～0.19%, Si:0.10% are following, Mn:1.00～2.50%, P:0.01～0.12%, S:0.26～0.63%, Al:0.010% are following, N:0.0030～0.0250%, O (oxygen): 0.005～0.035% and Te:0.002～0.100%, surplus is Fe and unavoidable impurities, is more than 4.0 by the value of the fn1 of following formula (1) expression.
fn1＝Mn/S… (1)
Also have, the symbol of element in (1) formula represents that this element is in content in the steel of quality %.
(2) a kind of low carbon free cutting steel, wherein, in quality %, contain that C:0.03～0.19%, Si:0.10% are following, Mn:1.20～2.50%, P:0.01～0.12%, S:0.26～0.63%, Al:0.010% are following, N:0.0030～0.0250%, O (oxygen): 0.005～0.035% and Te: surpass 0.010% and below 0.100%, surplus is Fe and unavoidable impurities, is more than 4.5 by the value of the fn1 of following formula (1) expression.
fn1＝Mn/S… (1)
Also have, the symbol of element in (1) formula represents that this element is in content in the steel of quality %.
(3) above-mentioned (1) or (2) described low carbon free cutting steel wherein, replace the part of Fe, in quality %, contain among Cr:0.04～1.25%, Ni:0.04～0.60% and Mo:0.04～0.40% more than a kind.
(4) each described low carbon free cutting steel in above-mentioned (1)～(3) wherein, also satisfies the value of the fn2 that is represented by following formula (2) more than 2.1.
fn2＝(S/10Te)+Mn… (2)
Also have, the symbol of element in (2) formula represents that this element is in content in the steel of quality %.
Below, the invention of the low carbon free cutting steel of above-mentioned (1)～(4) is called " the present invention (1) "～" the present invention (4) ".Be generically and collectively referred to as " the present invention " in addition.
Although steel of the present invention is " quick-tuming steel useful to global environment " that does not contain Pb, but have than the more good machinability of existing P b quick-tuming steel, and hot workability is also good than existing Bi quick-tuming steel, thereby can not crack and peel off flaw, excellent on productivity, therefore can be as the former material utilization of the soft miniature part that not too needs intensity.
Description of drawings
Fig. 1 illustrates that then MnS breaks, and can access the littler mode chart near granulous MnS of long-width ratio thus if " the compound quick-tuming steel of S-Te " implemented Wire Drawing.
Fig. 2 is that the explanation of medelling ground is implemented Wire Drawing and the shape of splitted MnS to the existing P b quick-tuming steel that does not add Te.
Embodiment
Below be described in detail for each important document of the present invention.Also have, " % " of the content of chemical ingredients is the meaning of " quality % ".
C：0.03～0.19％
C is known to be the element that improves the intensity of steel, but that intensity and machinability have is very strong related, and intensity uprises if the content of C is many, then machinability reduction.Particularly if the content of C surpasses at 0.19% o'clock, then along with the rising of intensity, the reduction of machinability is remarkable.On the other hand, if the content of C tails off, then intensity reduces, and can produce the detrimentally affect of squeeze crack etc. when cutting, and can not guarantee the desired intensity of part.Particularly if the content of C is lower than 0.03%, then along with intensity reduces, becoming of squeeze crack is remarkable.Therefore, the content of C is 0.03～0.19%.
Also have, the content of C is preferably 0.04～0.15%, and more preferably 0.05～0.10%
Below the Si:0.10%
If Si to contain quantitative change many, then deoxidation excessively promotes and the sulfide miniaturization, and the reduction of machinability takes place.Particularly if the content of Si surpasses 0.10%, then extremely miniaturization of sulfide causes the remarkable reduction of machinability.Therefore the content of Si is below 0.10%.
Also have, in order to suppress the sulfide miniaturization machinability can not be reduced, the content of preferred Si is below 0.02%, if 0.015% with next more preferred.
Mn:1.00～2.50% (the present invention (1)), 1.20～2.50% (the present invention (2))
Mn forms sulfide, is to be used to improve the necessary element of machinability.Mn suppresses the formation of FeS in addition in addition, prevents the effect that hot workability reduces.But the content of Mn is lower than at 1.00% o'clock and can not get these effects.On the other hand, if exceedingly Mn is contained, the content that causes the reduction of hot workability, particularly Mn on the contrary surpasses at 2.50% o'clock, and it is big that the reduction of hot workability becomes.Therefore, in the present invention (1), the content of Mn is 1.00～2.50%.
Also have, if the content of Mn becomes more than 1.20%, it is big that the effect of then above-mentioned Mn further becomes.Therefore in the present invention (2), the content of Mn is 1.20～2.50%.
More preferably Mn content is above 1.40% and below 2.50%, most preferably above 1.50% and below 2.50%.
P：0.01～0.12％
P is an EMBRITTLEMENT ELEMENTS, has the effect that improves machinability.In order to obtain described effect, the content that needs P is more than 0.01%.On the other hand, if the content of P becomes excessive, then cause the reduction of hot workability, particularly if the content of P surpasses 0.12%, then the reduction of hot workability is remarkable.Therefore the content of P is 0.01～0.12%.Also have, the lower value of P content is preferably 0.04%.
S：0.26～0.63％
S forms sulfide with Mn, is to be used to improve the necessary element of machinability, need make it to contain more than 0.26%.But if the content of S becomes excessively, cause that then the content of the reduction of hot workability, particularly S surpasses at 0.63% o'clock, the reduction that hot-work is given birth to is remarkable.Therefore, the content of S is 0.26～0.63%.The content of S is preferably 0.28～0.49%, and more preferably 0.28～0.35%.
Below the Al:0.010%
If the amount of Al is many, then deoxidation excessively promotes, sulfide miniaturization, the reduction that produces machinability.Particularly if the content of Al surpasses 0.010%, then extremely miniaturization of sulfide causes that machinability significantly reduces.Therefore Al content is below 0.010%.
Also have, in order to suppress the sulfide miniaturization machinability can not be reduced, the content of preferred Al is below 0.002%, if 0.015% with next more preferred.
N：0.0030～0.0250％
In the present invention, in order to adjust the intensity change of steel according to the change of Mn content, need contain the N more than 0.0030%.Yet if the content of N surpasses 0.0250%, machinability reduces significantly along with the intensity rising, and the reduction of hot workability is remarkable.Therefore, the content of N is 0.0030～0.0250%.Also have, the content of N is preferably 0.0030～0.0150%.
O (oxygen): 0.005～0.035%
In the present invention who applies flexibly this effect of machinability that improves MnS, O (oxygen) is extremely important element.That is, the effect that O has is that MnS is maximized, and improves the machinability of low carbon free cutting steel of the present invention.Yet the content of O is lower than at 0.005% o'clock, can not get described effect.On the other hand, if the content of O is excessive, then cause the reduction of hot workability, particularly then the content of O surpasses at 0.035% o'clock, and then the reduction of hot workability is remarkable.Therefore, the content of O is 0.005～0.035%.Also have, the content of O is preferably 0.010～0.035%.
Te:0.002～0.100% (the present invention (1)) is above 0.010% and in (the present invention (2)) below 0.100%
The effect that Te has is, suppresses the extension of MnS when hot-work, the long-width ratio (" length/width ") of MnS maintained smaller value, thereby improve machinability.In order to obtain above-mentioned effect, need contain Te is more than 0.002%.Yet, if the content of Te is excessive, cause the reduction of hot workability, particularly if the content of Te surpasses 0.100%, then the reduction of hot workability is remarkable.Therefore, in the present invention (1), the content of Te is 0.002～0.100%.
Also have,, then the long-width ratio of above-mentioned MnS is maintained little value and to improve the effect of machinability bigger if the content of Te surpasses 0.010%.Therefore in the present invention (2), the content of Te is above 0.010% and below 0.100%.
Fn1:4.0 above (the present invention (1)) is more than 4.5 (the present invention (2))
In containing the low carbon free cutting steel of the present invention of Te, the value of the fn1 that is represented by described (1) formula can access good hot workability 4.0 when above, can be in the generation that suppresses crackle and peel off flaw in the hot-work headed by the hot rolling.Therefore, in the present invention (1), the value of the fn1 that is represented by described (1) formula is more than 4.0.
Also have, under the value of fn1 is situation 4.5 or more, because can access better hot workability, so can be stable in the hot-work headed by the hot rolling and positively suppress crackle and peel off flaw.Therefore in the present invention (2), the value of the fn1 that is represented by described (2) formula is more than 4.5.
The value of fn1 more preferably more than 4.6, most preferably is more than 5.0.
Also have, the upper limit of the value of the fn1 that described (1) formula is represented does not have special stipulation, also can be according to 0.26% of the lower value of 2.50% and S content of the higher limit of the Mn content of having stated calculate 9.615.
From above-mentioned, the present invention's (1) low carbon free cutting steel regulation is as follows: contain the element from C to Te of above-mentioned scope, and the value of the fn1 that is represented by described (1) formula satisfies more than 4.0, surplus is made of Fe and impurity.
In addition, the present invention's (2) low carbon free cutting steel regulation is as follows: contain the element of above-mentioned scope from C to Te, and the value of the fn1 that is represented by above-mentioned (1) formula satisfies more than 4.5, surplus is made of Fe and impurity.
Also have, in low carbon free cutting steel of the present invention, except above-mentioned composition element, also can be as required as add arbitrarily element add again among the following element more than a kind: Cr:0.04～1.25%, Ni:0.04～0.60% and Mo:0.04～0.40%.
Below, describe with regard to above-mentioned any interpolation element.
Steel of the present invention can be as the former material utilization of the soft miniature part that not too needs intensity.Usually, the miniature part by machining is made collides in shell between the part when conveyance, rubs with other parts when assembling.At this moment, owing to be soft, so be very easy to stay flaws such as impacting vestige.Therefore according to circumstances, need prevent to be made into the strategy that impacts vestige behind the small article.
Also have, in order to prevent to impact vestige, effective means is the surface hardening processing of implementing to be called carburizing, when implementing carburizing treatment, if use the steel that contains Cr, Ni and Mo then can obtain efficiently.This is that by containing these elements, the depth of hardening after the carburizing deepens because Cr, Ni and Mo all are the elements that improve the hardenability of steel.In order positively to obtain this effect, the content of Cr, Ni and Mo is more than 0.04%.On the other hand, if exceedingly Cr, Ni and Mo are contained, then along with intensity rises, the reduction of machinability is remarkable, and manufacturing cost also uprises in addition.Particularly surpass 1.25%, contain Ni and surpass 0.60%, contain Mo and surpass 0.40%, then follow the rising of the reduction of the machinability that intensity rises and manufacturing cost remarkable if contain Cr.
Therefore, Cr, Ni during interpolation and the content of Mo are respectively 0.04～1.25%, 0.04～0.60%, 0.04～0.40%.
Also have, more preferred Cr, Ni during interpolation and the content of Mo are respectively 0.04～0.50%, 0.04～0.20%, 0.04～0.30%.
Above-mentioned Cr, Ni and Mo can only add any a kind, or compound interpolation is more than 2 kinds.
According to above-mentioned reason, the present invention's (3) low carbon free cutting steel is defined as, in quality %, contain among Cr:0.04～1.25%, Ni:0.04～0.60% and Mo:0.04～0.40% more than a kind, replace the part of Fe of the present invention (1) or the present invention's (2) low carbon free cutting steel with these elements.
More than the fn2:2.1
In containing the low carbon free cutting steel of the present invention of Te, the value of the fn2 that is represented by described (2) formula is 2.1 when above, by common Wire Drawing, for example by implementing to count 10～30% Wire Drawing with the section decrement, can access long-width ratio littler near granulous MnS, it is more good that machinability becomes.Therefore, the present invention's (4) low carbon free cutting steel is defined as, and the value of the fn2 that is represented by described (2) formula satisfies more than 2.1.
More preferably the value of fn2 is more than 2.5, if more than 3.0 then most preferably.
Also have, the upper limit of the value of the fn2 that is represented by described (2) formula does not have special stipulation, also can be according to the higher limit of the S content of having stated 0.63%, the higher limit of 0.002% and Mn content of the lower value of Te content 2.50% calculate 34.
Below, illustrate in greater detail the present invention by embodiment.
[embodiment 1]
[table 1]
* represent outside the prescribed condition of the present invention (1).</entry></row></tbody></tgroup></table></tables>
Enter the position of inner 20mm from the surface element of the ingot casting of above-mentioned each steel, the length of extracting diameter 10mm, parallel portion is the bar-shaped test film of 110mm, use hot-work to reproduce testing apparatus, after in atmosphere, carrying out ratio-frequency heating to 1250 ℃ and keeping 5 minutes, be cooled to 900 ℃ with 100 ℃/minute speed, making rate of straining is 10 seconds
-1And under 900 ℃, carry out high temperature tension test, investigate hot workability.Also have, the heating region of above-mentioned bar-shaped test film is the about 20mm of the central part of length direction, cooling immediately behind the high temperature tension test.In above-mentioned, as why selected 900 ℃ of the temperature of high temperature tension test, be because general under the situation of low carbon free cutting steel, be in minimal point in the constriction value of 900 ℃ of following drawing by high temperature.
Hot workability is estimated by the constriction rate (%) in the above-mentioned temperature tension test.Also have, adopt the ductility that is known as easy being heated under to hang down the steel 21 low carbon free cutting steel, that be equivalent to the Bi quick-tuming steel of this problems in asymmetic rolling, with 40% judgement criteria of the constriction value of its high temperature tension test as hot workability.
In addition, investigate the machinability of each steel, measure the long-width ratio of the MnS that influences machinability in addition according to the method for next setting forth.
That is, the surplus portion of the ingot casting of each steel is heated to 1300 ℃, carries out heat forged, make diameter 40mm round steel.Secondly, each above-mentioned round steel is heated to 900 ℃ after, keeps 1 hour enforcement anneal.
In order to remove the concavo-convex of surface and the Decarburized layer that causes of annealing, the round steel of the diameter 40mm that so obtains is carried out desquamation, finally become the round steel of diameter 31mm.
In addition, for steel 2, steel 7, steel 8 and steel 11, use a part of drawing of the round steel of above-mentioned diameter 31mm to be processed into the round steel of diameter 28mm.Also have, the cross section decrement of this drawing processing is 18.4%.
Diameter 31mm that obtains as above-mentioned and the round steel of 28mm are as supplying the examination material, use " the rotary cut blade of implementing the rapid tool steel SKH4 (JIS 4403 (2000)) of coating ", under the condition of roll surface speed: 100m/min, the amount of feed: 0.05mm/rev, incision concentration: 0.5mm, wet type, carry out rotary cut, measure from cutting and begin the average wear loss of the blade flank after 30 minutes and as the instrument wear loss.In addition, measure surperficial so-called " Rmax (maximum height) " that above-mentioned 30 minutes quilts behind the rotary cut are cut material.Also have, above-mentioned " Rmax " is equivalent in JIS B 0601 (2001), by the parameter that is called as " maximum height of profilograph " of the symbology of " Rz ".
In addition, each round steel for above-mentioned diameter 31mm and 28mm, take multiplying power in 8 R/2 (wherein " R " is the radius of round steel) cross section position, parallel with the length direction of round steel and be 400 optical microscope photograph, measure the long-width ratio of each MnS, with the long-width ratio of its mean value as the MnS of each round steel.
Also have, when rotary cut is equivalent to the round steel of steel 20 this diameter 31mm of existing P b quick-tuming steel, with instrument wear loss (265 μ m) and Rmax (10.0 μ m) respectively as the instrument wear loss of machinability and the judgement criteria of Rmax.
In table 2, merge and show each above-mentioned test-results.
In table 2, the long-width ratio of " L/W " expression MnS.In addition, for steel 2, steel 7, steel 8 and steel 11, in order to represent to cause the long-width ratio of MnS to diminish by drawing processing, " Δ L/W " hurdle is set, it is long-width ratio poor of MnS of the round steel that carries out drawing processing of the long-width ratio of MnS of round steel of diameter 31mm and diameter 28mm.
" zero " and " * " shown in the side of the numerical value on " hot constriction rate " hurdle of table 2, expression and comparison qualitatively as the constriction of judgement criteria value 40%, therefore " zero " meaning is that hot workability " is equal above level with existing Bi quick-tuming steel ", and " * " meaning is hot workability " poorer than existing Bi quick-tuming steel ".And " # " meaning of numerical value side is a judgement criteria.
In addition, " ◎ " shown in the numerical value side of " instrument wear loss " La, " zero " and " * " represent and comparison as 265 μ m of judgement criteria qualitatively, " ◎ " meaning is that the instrument wear loss as the evaluation of machinability " is lower than half of existing P b quick-tuming steel; few ", and " zero " meaning is that the instrument wear loss " is lacked than existing P b quick-tuming steel "." * " meaning is instrument wear loss " more than existing P b quick-tuming steel ".And " # " meaning of numerical value side is a judgement criteria.
In addition, " ◎ " shown in the numerical value side on " Rmax " hurdle, " zero " and " * ", expression and comparison qualitatively as 10.0 μ m of judgement criteria, " ◎ " meaning is that the Rmax as the evaluation of machinability " is lower than existing P b quick-tuming steel; the surface is slick ", and " zero " meaning is Rmax " littler than existing P b quick-tuming steel "." * " meaning is Rmax " bigger than existing P b quick-tuming steel, surface irregularity ".And " # " meaning of numerical value side is a judgement criteria.
[table 2]
# represents judgement criteria.</entry></row></tbody></tgroup></table></tables>
As shown in Table 2, the situation that the chemical constitution of steel breaks away from steel 4 (test number 5), steel 16 (test number 20) and the steel 17 (test number 21) of the present invention (1) defined terms is, " hot constriction rate " is lower than 40% of judgement criteria, and hot workability is poor.
Similarly, the situation that the chemical constitution of steel breaks away from steel 5 (test number 6), steel 15 (test number 19), steel 18 (test number 22) and the steel 19 (test number 23) of the present invention (1) defined terms is, " instrument wear loss " is for being higher than 265 μ m of judgement criteria, and " Rmax " also is higher than 10.0 μ m of judgement criteria, and machinability is bad.
With respect to this, the chemical constitution of steel satisfies under the situation of steel 1～3 in the table 1 of the present invention (1)～(3) defined terms and steel 6～14, and both are all excellent for hot workability and machinability as can be known.Also have, among above-mentioned the steel steel 1～3 and steel 6～14, the cross section decrement has been carried out steel 2, steel 7 and the steel 8 that also satisfies the present invention (4) defined terms as 18.4% under the situation of test number 3, test number 9 and test number 11 of drawing processing, as can be known because the long-width ratio of MnS diminishes, so being evaluated as qualitatively of instrument wear loss and Rmax " ◎ ", machinability are extremely excellent.
[embodiment 2]
Steel 22～25 by the melting of 3t (ton) atmosphere calciner has the chemical constitution shown in the table 3 is cast as ingot casting.Steel 22～24th in the table 3, chemical constitution are in the steel of the example of the present invention in the scope of the present invention regulation.On the other hand, the steel in the table 3 25 is steel that are equivalent to existing Bi quick-tuming steel that chemical constitution breaks away from the present invention's regulation.Also have, among the steel of comparative example, steel 20 is the steel that are equivalent to existing P b quick-tuming steel, also has, and for the steel 25 that does not contain Te, the value of " fn2 " becomes " infinity " in table 3.Therefore, for this steel 25 by " ∞ " expression " fn2 " hurdle.
[table 3]
* represent outside the prescribed condition of the present invention (1).</entry></row></tbody></tgroup></table></tables>
Secondly, after above-mentioned each ingot casting is heated to 1300～1350 ℃, it is rolling and become the steel billet at 140mm angle to carry out piecemeal, in addition, with soaking temperature: 1250 ℃ ± 20 ℃, soaking time: 30～40 minutes, finishing temperature: 1000 ℃ ± 30 ℃ condition, suppose the rolling experiment of real machine operation, finally become the wire rod of diameter 5.5mm.
Condition of surface to the wire rod of the diameter 5.5mm that so obtains is carried out visual observation, and investigation has or not peels off flaw and crackle.Its result can confirm that the situation of steel 22～24 is all not peel off flaw and crackle on any wire rod of diameter 5.5mm, even steel 22～24 still has good hot workability in the rolling experiment of supposition real machine operation.
On the other hand, the situation that is equivalent to the steel 25 of existing Bi quick-tuming steel is to have scattered the small flaw that peels off on the wire rod of diameter 5.5mm.
More than, specifically understand the present invention by embodiment, but the present invention is not limited by these embodiment.If do not have disclosed content to satisfy important document of the present invention as embodiment, be also contained among the present invention certainly.
[industrial utilize possibility]
Although steel of the present invention is " quick-turning steel useful to earth environment " that does not contain Pb, have Than the more good machinability of existing Pb quick-turning steel, and hot-workability is than existing Bi quick-turning steel Also more good, thus can not crack and peel off flaw, excellent on productivity, therefore can As the not too former material utilization of necessary soft baby part of intensity.
Claims (4)
1. low carbon free cutting steel, it is characterized in that, in quality %, contain that C:0.03～0.19%, Si:0.10% are following, Mn:1.00～2.50%, P:0.01～0.12%, S:0.26～0.63%, Al:0.010% are following, N:0.0030～0.0250%, O:0.005～0.035% and Te:0.002～0.100%, surplus is Fe and unavoidable impurities
And, be more than 4.0 by the value of the fn1 of following formula (1) expression,
fn1＝Mn/S… (1)
Also have, the symbol of element in (1) formula represents that this element is in content in the steel of quality %.
2. low carbon free cutting steel, it is characterized in that, in quality %, contain that C:0.03～0.19%, Si:0.10% are following, Mn:1.20～2.50%, P:0.01～0.12%, S:0.26～0.63%, Al:0.010% are following, N:0.0030～0.0250%, O:0.005～0.035% and Te: surpass 0.010% but below 0.100%, surplus is Fe and unavoidable impurities
And, be more than 4.5 by the value of the fn1 of following formula (1) expression,
fn1＝Mn/S… (1)
Also have, the symbol of element in (1) formula represents that this element is in content in the steel of quality %.
3. low carbon free cutting steel according to claim 1 and 2 is characterized in that, replaces the part of Fe, in quality % also contain in Cr:0.04～1.25%, Ni:0.04～0.60% and Mo:0.04～0.40% more than a kind.
4. according to each described low carbon free cutting steel in the claim 1～3, it is characterized in that the value that also satisfies the fn2 that is represented by following formula (2) is more than 2.1,
fn2＝(S/10Te)+Mn… (2)
Also have, the symbol of element in (2) formula represents that this element is in content in the steel of quality %.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2004352271A JP4507865B2 (en) | 2004-12-06 | 2004-12-06 | Low carbon free cutting steel |
| JP352271/2004 | 2004-12-06 |
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| CN101072891A true CN101072891A (en) | 2007-11-14 |
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| JP (1) | JP4507865B2 (en) |
| KR (1) | KR20070085739A (en) |
| CN (1) | CN101072891A (en) |
| TW (1) | TWI282374B (en) |
| WO (1) | WO2006062053A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111441004A (en) * | 2020-05-19 | 2020-07-24 | 首钢贵阳特殊钢有限责任公司 | Sulfur-lead-bismuth-tellurium composite series free-cutting steel |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5319169B2 (en) * | 2008-06-10 | 2013-10-16 | 秋山精鋼株式会社 | Manufacturing method of steel material and manufacturing method of steel parts |
| KR101187942B1 (en) | 2010-07-19 | 2012-10-04 | 주식회사 포스코 | LOW CARBON Pb FREE FREE-CUTTING STEEL WIRE ROD HAVING EXCELLENT MACHINABILITY |
| WO2018159617A1 (en) * | 2017-02-28 | 2018-09-07 | Ｊｆｅスチール株式会社 | Wire rod for cutting |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPS55138064A (en) * | 1979-04-10 | 1980-10-28 | Daido Steel Co Ltd | Free-cutting steel having excellent rolling fatigue strength |
| JP2740982B2 (en) * | 1990-02-28 | 1998-04-15 | 株式会社神戸製鋼所 | Free-cutting rope with high precision of the finished surface and method of manufacturing the same |
| JPH07173573A (en) * | 1993-12-17 | 1995-07-11 | Kobe Steel Ltd | Free-cutting steel excellent in machinability by carbide tool and internal quality |
| JP3854878B2 (en) * | 2002-03-07 | 2006-12-06 | 株式会社神戸製鋼所 | Low carbon sulfur-based free-cutting steel wire and method for producing the same |
| JP4267260B2 (en) * | 2002-06-14 | 2009-05-27 | 新日本製鐵株式会社 | Steel with excellent machinability |
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- 2004-12-06 JP JP2004352271A patent/JP4507865B2/en not_active Expired - Fee Related
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111441004A (en) * | 2020-05-19 | 2020-07-24 | 首钢贵阳特殊钢有限责任公司 | Sulfur-lead-bismuth-tellurium composite series free-cutting steel |
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| Publication number | Publication date |
|---|---|
| JP4507865B2 (en) | 2010-07-21 |
| TW200626732A (en) | 2006-08-01 |
| WO2006062053A1 (en) | 2006-06-15 |
| JP2006161087A (en) | 2006-06-22 |
| TWI282374B (en) | 2007-06-11 |
| KR20070085739A (en) | 2007-08-27 |
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