CN1205036A - Steel having excellent machinability and machined component using said steel - Google Patents

Steel having excellent machinability and machined component using said steel Download PDF

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Publication number
CN1205036A
CN1205036A CN97191416A CN97191416A CN1205036A CN 1205036 A CN1205036 A CN 1205036A CN 97191416 A CN97191416 A CN 97191416A CN 97191416 A CN97191416 A CN 97191416A CN 1205036 A CN1205036 A CN 1205036A
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steel
content
effect
machinability
value
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CN1095503C (en
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渡里宏二
冈田康孝
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Nippon Steel Corp
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Sumitomo Metal Industries Ltd
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Priority claimed from JP00197497A external-priority patent/JP3494271B2/en
Priority claimed from JP01604797A external-priority patent/JP3534146B2/en
Priority claimed from JP04313897A external-priority patent/JP3489376B2/en
Application filed by Sumitomo Metal Industries Ltd filed Critical Sumitomo Metal Industries Ltd
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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
    • 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
    • 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
    • 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
    • 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 steel products of the present invention are endowed with excellent machinability and have the following composition based on % by weight: C: 0.05% to 0.6%; S: 0.002% to 0.2%; Ti: 0.04% to 1.0%; N: 0.008% or less; Nd: 0% to 0.1%; Se: 0% to 0.5%; Te: 0% to 0.05%; Ca: 0% to 0.01%; Pb: 0% to 0.5%; and Bi: 0% to 0.4%; wherein the maximum diameter of titanium carbosulfide contained in the steel is not greater than 10 mu m, and its amount expressed in the index of cleanliness of the steel is equal to or more than 0.05%. The machined parts, according to the present inventions are manufactured by subjecting the steel products of the invention to a machining process, and are useful as structural steel parts for a variety of machinery, such as transportation machinery including automobiles, machinery for industrial use, construction machinery, and the like.

Description

The steel of excellent in machinability and the parts that become through machining with these steel
The present invention relates to a kind of steel of excellent in machinability and the parts that become through machining with this material.In detail, relate to a kind of good cutting ability that has, and being suitable for doing with the automobile is the steel of raw material of the structure unit such as Transport Machinery, industrial machine, construction implement of representative, reach with these steel as raw material, by the various machine structural parts of machining such as bent axle, connecting rod, gear one-tenth.
As everyone knows, various machine structural parts such as Transport Machinery, industrial machine, construction implement were made by following manner in the past, that is: (a) with hot-work roughing become given shape, then, after being finish-machined to desirable shape by machining, quench and modifier treatment such as tempering; After perhaps (b) carries out hot-work and quenching and temper,, be processed into desirable shape through machining.
But along with the machine structural parts high strength, the cost of machining also increases, and is strong day by day to the requirement of the free-cutting steel of excellent in machinability.
People know, if easy element of contact (improving the machinability element) such as independent or compound interpolation Pb, Te, Bi, Ca or S can improve machinability in steel.For this reason, existing people of past knows that employing adds above-mentioned easy element of contact in the steel that with the steel for mechanical structure is representative, improves the method for machinability.But, when in steel for mechanical structure etc., only adding easy element of contact separately, can not guarantee desirable mechanical characteristics (for example, toughness and fatigue strength) often.
Under these circumstances, after the hot-work of above-mentioned (a),, quench again and the technology of temper, for example, once reported in flat 2-111842 communique of Yu Tekai and the flat 6-279849 communique of Te Kai through machining.That is to say, this method is that the C in the steel is existed with graphite formation, makes " machinability, the hot rolling system steel that hardenability is good " of machinability raising reach " manufacture method of the steel for mechanical structure of excellent in machinability " by breach and the lubricant effect that utilizes this graphite.
But, open the steel of being reported in the flat 2-111842 communique the spy, make the separate out nucleus of nitrogenize B (NB) as graphite in order to add B, to promote greying, must add B, exist the problem that when solidifying, easily generates slight crack.On the other hand, open the method for being reported in the flat 6-279849 communique the spy, in the time of with interpolation Al, O (oxygen) amount is low in the restriction steel, in the state promotion greying of hot direct rolling., handle for this reason, can not say it to be economical in the graphitizing annealing that must carry out after the hot rolling more than 5 hours.
In addition, after the hot-work of carrying out above-mentioned (b) and Q-tempering were handled, the technology of machining for example specially opened that flat 6-212347 communique reported.This technology is to have direct quenching after the steel heat forged that particular chemical forms, to carry out temper thereafter, to separate out " the forge hot goods and the manufacture method thereof of the high-fatigue strength of tool " of TiC.But,, therefore, can not guarantee to have good machinability sometimes by only being defined as below 0.1 as the N amount of the chemical constitution of steel ratio N/Ti with the Ti amount at the forge hot goods described in this communique.That is to say, % by weight, the N amount that will contain the steel of 0.01-0.20%Ti represents only to stipulate 0.1 when following with N/Ti, then forms the TiN of hard in large quantities, has the situation that machinability degenerates that produces, and, also there is the situation that toughness degenerates that produces.
Once being reported in deoxidation in " iron and steel " (Vol.57 S484 (1971)) adjusts in the free cutting steel if interpolation Ti can improve machinability.But, at heavy addition Ti, thereby when generating TiN in a large number, the instrument abrasion is increased, find out from the machinability angle to be considered to ideal.For example, with the steel that contains C:0.45%, Si:0.29%, Mn:0.78%, P:0.017%, S:0.041%, Al:0.006%, N:0.0087%, TI:0.228%, O:0.004% and Ca:0.001%, anti-to reducing bit life, machinability is bad.Like this, in steel, only add Ti separately and can not improve machinability.
The purpose of this invention is to provide a kind of good machinability that has, be suitable for as various mechanical structures parts such as the Transport Machinery that with the automobile is representative, industrial machine, construction implements steel, and be that raw material carries out the various machine structural parts that machining such as bent axle, connecting rod, gear form with its steel.
Technology of the present invention is main as following:
(I) be by weight % contain that C:0.05-0.6%, S:0.002-0.2%, Ti:0.04-1.0%, N:0.008% are following, the chemical constitution of Nd:0-0.1%, Se:0-0.5%, Te:0-0.05%, Ca:0.01%, Pb:0-0.5%, Bi:0-0.4%, the maximum diameter of the carbon sulfide of Ti is below the 10 μ m in the steel, and its amount is the steel of the excellent in machinability more than 0.05% by purity.
(II) be contain that C:0.2-0.6%, Si:0.05-1.5%, Mn:0.1-2.0%, P:0.07% are following, S:0.01-0.2%, Al:0.002-0.05%, Cu:0-1.0%, Ni:0-2.0%, Cr:0-2.0%, Mo:0-0.5%, V:0-0.3%, Nb:0-0.1%, the chemical constitution that all the other are made of Fe and unavoidable impurities, and its tissue is ferrite and pearlitic above-mentioned (I) described non-hardened and tempered steel material more than 90%.
(III) be to contain C:0.05-0.3%, Si:0.05-1.5%, Al:0.002-0.05%, Cu:0-1.0%, Mo:0-0.5%, V:0-0.30%, Nb:0-0.1%, B:0-0.02%, the value that satisfies with the represented fn3 of following formula is 2.5-4.5%, the chemical constitution that all the other are made of Fe and unavoidable impurities, and, its tissue be bainite more than 90%, perhaps be the non-hardened and tempered steel material described in above-mentioned (I) of ferrite and bainite:
fn3=0．5Si(％)+Mn(％)+1．13Cr(％)+1．98Ni(％)
(IV) be to contain C:0.1-0.6%, Si:0.05-1.5%, Mn:0.4-2.0%, Al:0.002-0.05%, Cu:0-1.0%, Ni:0-2.0%, Cr:0-2.0%, Mo:0-0.5%, V:0-0.3%, Nb:0-0.1%, B:0-0.02%, the chemical constitution that all the other are made of Fe and unavoidable impurities, and, its tissue be the non-hardened and tempered steel material described in martensitic above-mentioned (I) more than 50%.
(V) be that the steel described in above-mentioned (I) are made material, the parts that form through machining.
(VI) be that the non-hardened and tempered steel material described in above-mentioned (II) is made material, the parts that form through machining.
(VII) be that the non-hardened and tempered steel material described in above-mentioned (III) is made material, the parts that form through machining.
(VIII) be that the modified steel described in above-mentioned (IV) are made material, the parts that form through machining.
In addition, the sulfide that also contains the Ti of simple formation in said in the present invention " the carbon sulfide of Ti ".
Said in this manual " (the carbon sulfide of Ti) maximum diameter " is meant at " longest diameter in the carbon sulfide of each Ti ".
The purity of the carbon sulfide of Ti is to make the magnification of opticmicroscope become 400 times, the value that " the microscopic method of the non-metallic inclusion of steel " 60 visual fields by the JIS0555 defined are measured.
Also have, so-called in this manual " non-hardened and tempered steel material ", be meant the steel that omit as " quenching and tempering " of so-called " modifier treatment ", also contain " steel that can use at the direct state of hot-work postcooling " and " after hot worked cooling, carrying out the steel of suitable tempered ageing treatment "." modified steel " also claim to quench and the tempered steel.
The ratio of tissue is organized ratio when being microscopic examination, promptly is called the area ratio.
About above-mentioned (II), claim " ferrite and perlite are more than 90% ", be meant that the shared ratio sum of ferrite and perlite is more than 90% in ferrite and perlite blended tissue.
About above-mentioned (III), claim " bainite is more than 90% ", be meant that when not containing ferrite in tissue, bainite accounts for the situation more than 90% of tissue; Claim " ferrite and bainite are 90% ", be meant that ferrite and the shared ratio sum of bainite are more than 90% in the tissue when bainite and ferrite mix.
About above-mentioned (IV), claim " martensite is more than 50% ", be meant that martensite accounts for the situation more than 50% of tissue.Also have, described (IV) about carrying out quenching and tempering " modified steel ", therefore above-mentioned martensite is meant tempered martensite, i.e. " tempered martensite " is hereinafter to be referred as " martensite ".
The chemical constitution and tissue influence to machinability and mechanical property of present inventors in order to study steel tested repeatedly.
Its result at first finds, (a) an amount of Ti, (b) of interpolation makes sulfide become the carbon sulfide of Ti as the inclusion in the control steel in steel, and (c) if the carbon sulfide of above-mentioned Ti is disperseed imperceptibly, the machinability of steel rapidly improves.
And, continue the phenomenon that its result of research has also found following (d)-(p) further.
(d) in containing the steel of an amount of S, add Ti on one's own initiative, just can form the carbon sulfide of Ti in the steel.
(e) generate the carbon sulfide of above-mentioned Ti in steel, the growing amount of MnS just reduces.
When (f) the S amount in steel was identical, the carbon sulfide of Ti had the effect of improving machinability bigger than MnS.This may be because the fusing point of the carbon sulfide of Ti is lower than the fusing point of MnS, and the lubrication of tool surfaces becomes big during based on machining.
(g) improve the effect of machinability for the carbon sulfide that can give full play to Ti, restriction N content is below 0.008%, is important to suppressing separating out of TiN.
(h) minimizing of the TiN in restriction N content and the steel is relevant, therefore, can improve the toughness in the mechanical property.
(i) for the carbon sulfide that utilizes Ti improves machinability, suitably select Ti carbon sulfide size and be important with the represented amount of its purity (hereinafter to be referred as purity).
(j) the carbon sulfide of the Ti that when the system steel, is generated, being used under common hot worked Heating temperature and the Heating temperature that is used for quenching usually, not molten admittedly on parent in modifier treatment.Therefore, the carbon sulfide of Ti is brought into play so-called " obstruction " effect in austenitic range, can prevent thickization of austenite crystal effectively.Certainly, the carbon sulfide of Ti, for common tempered Heating temperature and under the Heating temperature that is equivalent to the tempered ageing treatment, not molten admittedly on parent in modifier treatment yet.
(k) being ferrite and pearlitic steel more than 90% for what organize, is very little by the crooked and generation unrelieved stress of being out of shape mutually.
(l) intensity and the flexible equilibrium that is organized as more than 90% to the steel of bainite or ferrite and bainite is good.
(m) be very good for the intensity of martensitic steel and flexible equilibrium more than 50% of tissue.
(n) has specific chemical ingredients, what organize is in ferrite and the pearlitic non-hardened and tempered steel material more than 90%, ferritic ratio is pressed area than being 20-70%, ferritic granularity is more than 5 by JIS granularity label, the mean value of pearlitic thin layer spacing is below the 0.2 μ m, if can satisfy a condition in these conditions at least, just can obtain good intensity and flexible equilibrium.
(o) bigger and/or with the value of the represented fn2 of following formula (2) when bigger than 2 than 0% with the value of the represented fn1 of following formula (1), the effect change that the carbon sulfide of Ti improves machinability greatly.And, with the value of the represented fn2 of formula (2) than 2 greatly the time, the blockage effect of the carbon sulfide of Ti also becomes greatly, can obtain big intensity and good toughness:
fn1=Ti(％)-1．2S(％)????(1)；
fn2=Ti(％)／S(％)???????(2)。
(p) relevant with the value of the represented fn3 of following formula (3) with the tissue and the toughness of non-hardened and tempered steel material with specific chemical constitution, if this value in specific scope, tissue be bainite more than 90%, perhaps be ferrite and bainite:
fn3=0．5Si(％)+Mn(％)+1．13Cr(％)+1．98Ni(％)????(3)。
The present invention is based on above-mentioned discovery and finishes.Below, explain each main composition of the present invention.Wherein, the amount of each element " % " is with " weight % " expression.
(A) chemical constitution of steel
C：
C combines with Ti with S simultaneously, forms the carbon sulfide of Ti, has the effect that improves machinability.And carbon is for guaranteeing that the intensity aspect also is an effective elements.But carbon content is below 0.05%, can not obtain its effect.On the other hand, carbon content surpasses 0.6%, and toughness will reduce.Therefore, the amount of C is decided to be 0.05-0.6%.
In addition, tissue be that the C content of ferrite and pearlitic non-hardened and tempered steel material (hereinafter to be referred as " steel of condition X ") is that 0.2-0.6% is an ideal more than 90%, ideal is 0.25-0.5% more.
Tissue be bainite more than 90%, or the C content of the non-hardened and tempered steel material of ferrite and Bei Shi iron (hereinafter to be referred as " steel of condition Y ") is that 0.05-0.3% is an ideal, ideal is 0.1-24% more.
The C content for martensitic modulation steel (hereinafter to be referred as " steel of condition Z ") more than 50% of tissue is that 0.1-0.6% is an ideal
S：
S combines with Ti with C simultaneously, forms the carbon sulfide of Ti, and the effect that improves machinability is arranged.But its content is can not obtain its effect below 0.002%.
In the past, the purpose of adding sulphur in free cutting steel was to make to form MnS, can improve machinability.But,, distinguish that above-mentioned MnS improves the machinability effect and is based on the cutting when improving cutting and the oilness function of tool surfaces according to present inventors' check.Yet it is big that MnS becomes, and it is big that the hairline of steel main body becomes, and has the situation that causes shortcoming.
S improves the effect of machinability among the present invention, originally is by compound interpolation proper C and Ti, and the carbon sulfide that forms Ti obtains.For this reason, as described above the S content more than 0.002% must be arranged.On the other hand, S content surpasses 0.2%, and the effect that improves machinability is not changed, but generate thick MnS in the steel once more, thus problems such as generation hairline.And, degenerate significantly in the workability of heat condition, become difficult, toughness in the plastic working of heat condition and also reduce.Therefore, the content of S is decided to be 0.002-0.2%.
In addition, the S content of " steel of condition X " is that 0.01-0.2% is an ideal, and ideal is 0.02-0.17% more.
The S content of " steel of condition Y " is that 0.005-0.17% is an ideal.
Ti：
Ti is the important alloying element as the control inclusion in the present invention.Its content is 0.04% when following, owing to can not make S be converted into the carbon sulfide of Ti fully, can not improve machinability.On the other hand, Ti content had both made and had surpassed 1.0%, and the effect of improving machinability reaches capacity, and only upward cost increase, and toughness and hot workability significantly degenerate.Therefore, Ti content is decided to be 0.04-1.0%.
Also have, the Ti content of " steel of condition X " is that 0.08-0.8% is an ideal.
The Ti content of " steel of condition Y " is that 0.06-0.8% is an ideal.
The Ti content of " steel of condition Z " is that 0.06-0.8% is an ideal.
N content is below 0.008%.
In the present invention, control N content is low is very important.That is to say, because N combines with Ti greatly easily with the avidity of Ti, form TiN, Ti has been fixed, therefore, when containing N in a large number, the carbon sulfide that can not bring into play aforesaid Ti fully improves the effect of machinability.And thick TiN reduces toughness and machinability.Therefore, N content is decided to be below 0.008%.And for the effect of the carbon sulfide that improves Ti, being limited to 0.006% on the N content is ideal.
Nd：
Also can not add Nd.Add Nd, as Nd 2S 3Have the chip breaking effect, the effect that improves machinability is arranged.And, Nd 2S 3In the higher temperature range of the ratio of molten steel, disperse to generate imperceptibly, the back operation for the heating of hot-work and quenching the time, can suppress the growth of austenite crystal, make and organize miniaturization, the effect that makes steel high strength and high tenacityization is also arranged.For positively obtaining described effect, the content of Nd is to be ideal more than 0.005%.But its content surpasses 0.1%, Nd 2S 3Chap own is big, reduces instead cause toughness.Therefore, Nd content is 0-0.1%.And Nd content ideal higher limit is 0.08%.
Se：
Also can not add Se.Add Se, the effect of the machinability that improves steel is more arranged.For positively obtaining this effect, Se has the content ideal more than 0.1%.But its content surpasses 0.5%, and aforesaid effect is reached capacity, instead generate thick inclusion, causes that fatigue strength and/or flexible reduce.Therefore, Se content is decided to be 0-0.5%.
Te：
Also can not add Te.Add Te, the effect of the machinability of further raising steel is arranged.For positively obtaining this effect, Te content is being ideal more than 0.005%.But its content surpasses 0.05%, and aforesaid effect reaches capacity, instead generate thick inclusion, causes that fatigue strength and/or flexible reduce.And heavy addition Te causes hot workability and degenerates, and particularly, Te content surpasses 0.05%, and hot worked steel surface just produces slight crack.Therefore, Te content is decided to be 0-0.05%.
Ca：
Also can not add Ca.Add Ca, the effect of the machinability that improves steel is greatly arranged.For positively obtaining this effect, Ca content is 0.001% to be ideal.But its content surpasses 0.01%, and aforesaid effect reaches capacity, instead generate thick inclusion, causes that fatigue strength and/or flexible reduce.Therefore, the content of Ca is 0-0.01%.
Pb：
Also can not add Pb.Add Pb, the effect of the machinability that improves steel is more arranged.For positively obtaining this effect, it is ideal that Pb has the amount more than 0.05%.But its content surpasses 0.5%, and aforesaid effect reaches capacity, instead generate thick inclusion, causes that fatigue strength and/or flexible reduce.Therefore, the excessive interpolation of Pb causes hot workability and degenerates, and particularly, Pb content surpasses 0.5%, just produces slight crack at hot worked steel surface.Therefore, Pb content is decided to be 0-0.5%.
Bi：
Also can not add Bi.Add Bi, the effect of the machinability that improves steel is greatly arranged.For positively obtaining this effect, Bi content is that the content more than 0.05% is ideal.But its content surpasses 0.4%, and aforesaid effect reaches capacity, instead generate thick inclusion, causes that fatigue strength and/or flexible reduce.And, because hot workability worsens, produce slight crack on hot worked steel surface.Therefore, Bi content is decided to be 0-0.4%.
In the scope of relevant machinability, " steel of excellent in machinability " of the present invention are for the element beyond the C that had narrated, S, Ti, N, Nd, Se, Te, Ca, Pb and the Bi, the necessity that does not limit especially.But, concerning steel, except that machinability, also have the requirement of a lot of other characteristics, for example, by the crooked and generation residual stress requirement of distortion mutually, the equilibrium of strength and toughness will wait well.In this case, as long as relation is arranged, also can determine the chemical constitution of the element except that the C that had narrated, S, Ti, N, Nd, Se, Te, Ca, Pb and Bi with the steel tissue.
Below about the chemical constitution of the element beyond C, S, Ti, N, Nd, Se, Te, Ca, Pb and the Bi, the situation of dividing aforesaid " steel of condition X ", " steel of condition Y " to reach " steel of condition Z " describes.
(A-1) more than 90% of tissue be the situation of ferrite and pearlitic non-hardened and tempered steel material (" steel of condition X ").
Si：
Si has the effect of strengthening steel-deoxidizing and ferriteization.And, along with the increase of Si content, improve the effect of the cutting swarf surface lubrication of cutting, prolong life tools, therefore also have the effect that improves machinability.But its content is below 0.05%, lacks additive effect.On the other hand, surpass 1.5%, aforesaid effect reaches capacity, but toughness degenerates.Therefore, Si content is that 0.05-1.5% is good.And Si content is that 0.3-1.3% is an ideal, and ideal is 0.5-1.3% more.
Mn：
Mn is by strengthening the molten admittedly effect that improves fatigue strength that has.But its content is 0.1% when following, is difficult to obtain its effect.On the other hand, Mn content surpasses 2.0%, in the situation of " steel of condition X ", endurance ratio (fatigue strength/tensile strength) and yield ratio (yield strength/tensile strength) is reduced.Therefore, the content of Mn is that 0.1-2.0% is good.And ideal Mn content is 0.4-2.0%, and that better is 0.5-1.7%.
P：
Also can plan to add P.In " steel of condition X ", add P and have the effect that improves tensile strength and fatigue strength.For positively obtaining this effect, P content is to be ideal more than 0.01%.Yet P content surpasses 0.07%, and toughness is degenerated significantly.And reduction hot workability.Therefore, the content of P should be below 0.07%.Content when initiatively adding P is that 0.015-0.05% is an ideal.
Al：
Al is the deoxidation effective elements to steel.Yet its content is 0.002% when following, seldom arrives desired effect, and surpasses 0.05%, and its effect reaches capacity.Machinability is reduced.For this reason, the content of Al should be 0.002-0.05%.And the content of Al is that 0.005-0.03% is an ideal.
Cu：
Also can not add Cu.Add Cu, separate out, have the effect of the intensity, particularly fatigue strength that improve steel by reinforcement.For positively obtaining this effect, the content of Cu is to be ideal below 0.2%.Yet its content surpasses at 1.0% o'clock, will cause that hot workability degenerates, thickization of precipitate, and aforesaid effect also reaches capacity, and is anti-to reducing.And cost also increases.Therefore, the content of Cu should be 0-1.0%.
Ni：
Also can not add Ni.Add Ni, have the effect that improves intensity.For obtaining this effect really, the content of Ni is 0.02% to be ideal.Yet its content surpasses 2.0% o'clock this effect and reaches capacity, and cost increases.Therefore, the content of Ni can be decided to be 0-2.0%.
Cr：
Also can not add Cr.Add Cr,, the effect that improves fatigue strength is arranged owing to strengthen solid melting.For obtaining this effect really, the content of Cr is the ideal more than 0.02%.Yet its content surpasses 2.0%, and under the situation of " steel of condition X ", durable yield ratio when reduces.Therefore, the content of Cr is that 0-2.0% is good.And when adding Cr, its content is that 0.05-1.5% is an ideal.
Mo：
Also can not add Mo.Add Mo, what make that iron plain sheet and perlite constitute organizes miniaturization, has the effect of raising hardness of steel, particularly fatigue strength.For obtaining this effect really, be ideal more than 0.05% with the content of Mo.But its content surpasses 0.5%, instead make thickization of tissue abnormalities ground after the hot-work, reduces fatigue strength.Therefore, the content of Mo with 0-0.5% for well.
V：
Also can not add V.Add V, separate out, particularly have the effect that improves fatigue strength as fine nitride and oxycarbide.For obtaining this effect really, V content is in the ideal more than 0.05%.Yet its content surpasses 0.3%, because the precipitate chap is big, instead make the saturated or reduction of described effect.And, can only increase the cost of raw material.Therefore, the content of V should be 0-0.3%.
Nb：
Also can not add Nb.Add Nb, separate out, prevent thickization of austenitic bad grain, have the effect of the effect, particularly fatigue strength that improve hardness of steel simultaneously as fine nitride and oxycarbide.For obtaining this effect really, Nb content is 0.005% above ideal.Yet its content surpasses 0.1%, just makes the thick hard carbon nitride of the saturated generation of described effect, and the damage instrument causes cutting to reduce.Therefore, Nb content is that 0-0.1% is good.And being limited to 0.05% on the Nb content is ideal.
fn1、fn2：
As previously mentioned, with the value of the fn1 of described formula (1) expression when bigger than 0%, and/or with the value of the fn2 of described formula (2) expression than 2 greatly the time, the effect of the carbon sulfide raising machinability of Ti is big.And.With the value of the represented fn2 of formula (2) when bigger than 2, the blockage effect of the carbon sulfide of Ti also becomes greatly, and tensile strength and fatigue strength change are greatly.Therefore, the value of fn1 is bigger than 0%, and the value of fn2 is greatly an ideal than 2.And the upper limit of the value of above-mentioned fn1 and fn2 is not stipulated especially, can be the higher limit of its composition aspect yet.
, form the oxide inclusion of hard, damage cutting tool when cutting is arranged, the situation that machinability is reduced as the oxygen of impurity element.Particularly, oxygen level surpasses 0.015%, causes reducing significantly the situation of machinability.Therefore, in order to keep good machinability, should fix on below 0.015% as the oxygen level of impurity element.And oxygen level is to be ideal below 0.01%.
(A-2) situation of the non-hardened and tempered steel material of the Bei Shi more than 90% of tissue or ferrite and bainite (" steel of condition Y ").
Si：
Si has the effect that improves steel-deoxidizing and quenching.And, both made when " steel of condition Y ", owing to increase, improve the effect of the cutting swarf surface lubrication of cutting along with Si content, prolong life tools, can improve machinability.But its content is below 0.05%, lacks additive effect.On the other hand, its content surpasses 1.5%, and described effect is reached capacity, and toughness is degenerated.Therefore, Si content should be 0.05-1.5%.And Bi content is that 0.5-1.3% is an ideal.
Al：
Al is the element with strong desoxydatoin.In order to ensure its effect, Al content should be 0.002% when following.Yet Al content surpasses 0.05%, and its effect reaches capacity, and only increases cost.Therefore, the content of Al should be 0.002-0.05%.And the content of Al is that 0.005-0.04% is an ideal.
Cu：
Also can not add Cu.Add Cu, do not reduce toughness, improve the intensity of steel, and have the effect that improves machinability.For positively obtaining this effect, the content of Cu is to be ideal below 0.2%.Yet its content surpasses at 1.0% o'clock, brings to make that hot workability degenerates, thickization of precipitate, and described effect is saturated, toughness reduces.And, also just increase cost.Therefore, the content of Cu should be 0-1.0%.
Mo：
Also can not add Mo.Add Mo, can improve hardenability, organize miniaturization simultaneously, have the effect that improves hardness of steel.For obtaining this effect really, be ideal more than 0.05% with the content of Mo.But its content surpasses 0.5%, instead make thickization of tissue abnormalities ground after the hot-work, reduces fatigue strength.Therefore, the content of Mo with 0-0.5% for well.
V：
Also can not add V.Add V, separate out as fine nitride and oxycarbide, can improve the intensity of steel, simultaneously, the oilness of smear metal when improving cutting has the effect that improves cutting.For obtaining this effect really, V content is in the ideal more than 0.05%.Yet its content surpasses 0.30%, because bigization of precipitate chap, described effect reaches capacity, and reduces toughness.And, also can only increase the cost of raw material.Therefore, the content of V should be 0-0.30%.
Nb：
Also can not add Nb.Add Nb, separate out, prevent thickization of austenitic particulate, have the effect that improves hardness of steel, flexible effect, particularly fatigue strength simultaneously as fine nitride and oxycarbide.For obtaining this effect really, Nb content is 0.005% above ideal.Yet its content surpasses 0.1%, just makes described effect saturated, produces thick hard carbon nitride, and the damage instrument causes cutting and reduces.Therefore, Nb content should be 0-0.1%.
B：
Also can not add B.Add B, improve hardenability, have the hardness of steel of raising, flexible effect.For obtaining this effect really, B content is 0.0003% above ideal.Yet its content surpasses 0.02%, and described effect reaches capacity, instead reduce toughness.Therefore, B content should be 0-0.02%.
fn3：
As mentioned above, value with the fn3 of described formula (3) expression is relevant with the tissue and the toughness of the non-hardened and tempered steel material with specific chemical constitution, when the 2.5-4.5%, non-hardened and tempered steel is main is organized as bainite or ferrite and bainite, can obtain good intensity and flexible equilibrium in this value.
Related Si, Mn, Cr and the Ni of fn3 has the effect of the hardenability that improves steel, and still, this value is below 2.5%, can not obtain the effect of desired raising hardenability, and toughness reduces.On the other hand, the value of fn3 surpasses 4.5%, and it is too high that hardenability becomes, instead reduce toughness.Therefore, be that 2.5-4.5% is good with the represented fn3 of formula (3).In addition, the amount of each element beyond the aforesaid Si, if can satisfy described fn3 is that 2.5-4.5% is just passable, also not restriction especially.Yet the content of Mn, Cr and Ni is respectively 0.4-3.5%, below 3.0%, is ideal below 2.0%.
fn1、fn2：
When " steel of condition Y " are arranged, as previously mentioned, with the value of the fn1 of described formula (1) expression when bigger and/or with the value of the fn2 of described formula (2) expression than 0% than 2 greatly the time, the effect of the carbon sulfide raising machinability of Ti is big.And.When bigger than 2, the blockage effect of the carbon sulfide of Ti also becomes greatly with the value of the represented fn2 of formula (2), and tensile strength and fatigue strength become greatly.Therefore, the value of fn1 is bigger than 0%, and the value of fn2 is greatly an ideal than 2.In addition, the upper limit of the value of described fn1 and fn2 is not stipulated especially, can be the higher limit of its composition aspect yet.
Yet, form the oxide inclusion of hard as the O (oxygen) of impurity element, have when cutting, cutting tool is damaged, the situation that machinability is reduced.Particularly, there is oxygen level to surpass 0.015%, just causes the situation that machinability reduces significantly.Therefore, when meeting " steel of condition Y ", in order to keep good machinability, should fix on below 0.015% as the oxygen level of impurity element.And oxygen level is to be ideal below 0.01%.
Further, as impurity element P, from guaranteeing the toughness viewpoint of steel, its content is to be good below 0.05%.
(A-3) situation of the martensitic modified steel more than 50% of tissue (" steel of condition Z ")
Si：
Si has the effect that improves steel-deoxidizing and quenching.And, when " steel of condition Z " are arranged,, improve the effect of the cutting swarf surface lubrication of cutting with the increase of Si content, prolong life tools, can improve machinability.Yet its content is below 0.05%, lacks additive effect.On the other hand, its content surpasses 1.5%, and described effect is reached capacity, and toughness is degenerated.Therefore, Si content should be 0.05-1.5%.
Mn：
Mn can improve the hardenability of steel, owing to strengthen solid melting, has the effect that improves fatigue strength simultaneously.Yet its content is below 0.4%, can not obtain its effect, and surpasses 2.0%, and not only this effect reaches capacity, instead become really up to the mark, reduces toughness.Therefore, the content of Mn is with 0.4-2.0%.
Al：
Al is the element with strong desoxydatoin.In order to ensure its effect, its content should be more than 0.002%.Yet Al content surpasses 0.05%, and its effect is saturated, just increases cost.Therefore, the content of Al should be 0.002-0.05%.And the content of Al is that 0.005-0.04% is an ideal.
Cu：
Also can not add Cu.Add Cu, do not reduce toughness, improve the intensity of steel, and have the effect that improves machinability.For positively obtaining this effect, the content of Cu is to be ideal below 0.2%.Yet its content surpasses at 1.0% o'clock, will increase that hot workability degenerates, thickization of precipitate, and described effect is saturated, instead reduce its effect.And, cost is increased.Therefore, the content of Cu should be 0-1.0%.
Ni：
Also can not add Ni.Add Ni, have the quenching effect that improves steel.For obtaining this effect really, the content of Ni is 0.02% to be ideal.Yet its content surpasses 2.0% o'clock this effect and reaches capacity, and cost increases.Therefore, the content of Ni can be decided to be 0-2.0%.
Cr：
Also can not add Cr.Add Cr, improve the hardenability of steel, simultaneously,, the effect that improves fatigue strength is arranged because reinforcement is solid molten.For obtaining this effect really, the content of Cr is 0.03% to be ideal.Yet its content surpasses 2.0%, and not only described effect reaches capacity, instead really up to the mark, the reduction toughness that becomes.Therefore, the content of Cr is 0-2.0%.
Mo：
Also can not add Mo.Add Mo, have the quenching effect that improves steel.For obtaining this effect really, be ideal more than 0.05% with the content of Mo.Yet its content surpasses 0.5%, and not only this effect reaches capacity, and reaches firmly instead become, and reduces toughness, and cost has also increased.Therefore, the content of Mo should be 0-0.5%.
V：
Also can not add V.Add V, separate out, have the effect of the intensity, particularly fatigue strength that improve steel as fine nitride and oxycarbide.For obtaining this effect really, V content is in the ideal more than 0.05%.Yet its content surpasses 0.3%, because bigization of precipitate chap, described effect reaches capacity, instead reduce its effect.And, also can only increase the cost of raw material.Therefore, the content of V should be 0-0.3%.
Nb：
Also can not add Nb.Add Nb, separate out, prevent thickization of the bad grain of Austriaization body, have the effect of raising hardness of steel, particularly fatigue strength simultaneously as fine nitride and oxycarbide.For obtaining this effect really, Nb content is 0.005% above ideal.Yet its content surpasses 0.1%, just makes the hard carbon nitride that described effect is saturated, generation is thick, and the damage instrument causes reducing machinability.Therefore, Nb content should be 0-0.1%.And being limited to 0.05% on the Nb content is ideal.
B：
Also can not add B.Add B, improve hardenability, have the hardness of steel of raising, flexible effect.For obtaining this effect really, B content is 0.0003% above ideal.Yet its content surpasses 0.02%, and described effect reaches capacity, instead reduce toughness.Therefore, B content should be 0-0.02%.
fn1、fn2：
Both made when " steel of condition Z ", as stating, with the value of the fn1 of described formula (1) expression when bigger and/or with the value of the fn2 of described formula (2) expression than 0% than 2 greatly the time, the effect of the carbon sulfide raising machinability of Ti is big.And.When bigger than 2, the blockage effect of the carbon sulfide of Ti also becomes greatly with the value of the represented fn2 of formula (2), and tensile strength and fatigue strength become greatly.Therefore, the value of fn1 is bigger than 0%, and the value of fn2 is greatly an ideal than 2.In addition, the upper limit of the value of described fn1 and fn2 is not stipulated especially, can be the higher limit of its composition aspect yet.
, the oxide inclusion as the O (oxygen) of impurity element forms hard has damage instrument when cutting, the situation that machinability is reduced.Particularly, oxygen level surpasses 0.015%, will cause machinability to reduce significantly.Therefore, when " steel of condition Z " are arranged, in order to keep good machinability, should fix on below 0.015% as the oxygen level of impurity element.And oxygen level is to be ideal below 0.01%.
Further, as impurity element P, from guaranteeing the toughness viewpoint of steel, its content is to be good below 0.05%.
(B) size and the purity of the carbon sulfide of Ti
For the carbon sulfide by Ti improves the machinability that has at the steel of the chemical constitution described in above-mentioned (A), importantly make the size and the purity of carbon sulfide of Ti suitable.In addition, the sulfuration Ti that in what is called of the present invention " the carbon sulfide of Ti ", also comprises independent formation.
The amount of the carbon sulfide of the Ti below maximum diameter is 10 μ m is 0.05% when following by purity, can not bring into play the effect that the carbon sulfide that utilizes Ti improves machinability.Described purity is to be ideal more than 0.08%.Because the Reinheitszahl of the carbon sulfide of described Ti reaches greatly, there is the situation that reduces fatigue strength.Therefore, the higher limit of the purity of the carbon sulfide of described Ti is about 2.0% to be ideal.
At this, the size of the carbon sulfide of Ti is limited in below the 10 μ m by maximum diameter, be that fatigue strength and/or toughness just reduce because surpass 10 μ m.And the maximum diameter of the carbon sulfide of Ti is to be ideal below the 7 μ m.The maximum diameter of the carbon sulfide of this Ti is too small, diminishes owing to improve the machinability effect, and therefore, the lower value of the maximum diameter of the carbon sulfide of Ti is to be ideal about 0.5 μ m.
The form of the carbon sulfide of Ti is that the content with the Ti in the steel, S and N is determined basically.Yet, owing to, be important to preventing that the Ti oxide compound from excessively generating with the size of the carbon sulfide of Ti and purity value for regulation.Therefore, having steel only individual useful above-mentioned (A) described chemical constitution is inadequate situation, and for example, with Si and the abundant deoxidation of Al, adopting the system steel method of adding Ti at last is ideal.
In addition, the carbon sulfide of Ti carries out mirror ultrafinish by the coupons that adopts in the steel, and its abrasive surface is done detected, if observe with the opticmicroscope of magnification more than 400 times, with CF easily and other inclusion distinguish.That is to say that under described condition, if observe with opticmicroscope, " color " of the carbon sulfide of Ti is extremely shallow grey, its " shape " is considered to be equivalent to granular (spherical) of the B family inclusion of JIS.The detailed judgement of the carbon sulfide of Ti can be observed with the electron microscope of the analytic function that EOX (energy dispersion type x-ray analysis equipment) etc. is set.
At this, the purity of the carbon sulfide of Ti, such as described, be 400 times with the magnification of opticmicroscope, measure the value of 60 visual fields by " the micrographic test method of the non-metallic inclusion of steel " of eucalyptus JISG0555 regulation.
(C) tissue of steel
Relate to " steel of excellent in machinability " of the present invention, relevant machinability is limited to, and only stipulates the content of C, S, Ti, N, Nb, Se, Te, Ca, Pb and the Bi of described (A), and the size and the purity of the carbon sulfide of the Ti of described (B), and is promptly abundant.Yet, requiring machinability simultaneously to steel, when also requiring other characteristics, also can be with the regulation of organizing of steel.
At first, be ferrite and pearlitic situation more than 90% being organized as of steel, the problem that undergoes phase transition crooked residual stress is little.Therefore,, for example, do not need as the bridge of manufacturing procedure just (the positive operation of bridge) if steel tissue is ferrite and perlite more than 90%, relevant with the cost reduction.And, when described steel are the non-hardened and tempered steel material, can be reduced to the lot of energy and the cost of modifier treatment.
For the tissue that makes the non-hardened and tempered steel material more than 90% by ferrite and pearliticly constitute, will as stated the steel disc of chemical constitution of record in (II), after for example being heated to 1050-1300 ℃, carry out hot-work such as heat forged, processing the back under the temperature more than 900 ℃ with the speed of cooling below 60 ℃/minute, can carry out air cooling or place cooling, till 500 ℃.In addition, so-called in this manual " speed of cooling " is meant the speed of cooling of steel surface.
Situation at the non-hardened and tempered steel material of above-mentioned tissue, ferritic ratio is pressed area than being 20-70%, ferritic granularity is more than 5 by JIS granularity label, the mean value of pearlitic thin layer spacing is below the 0.2 μ m, if can satisfy above at least one condition, can obtain good intensity and flexible equilibrium.
Secondly, when the tissue 90% of steel was thought bainite or ferrite and bainite, intensity and flexible were balanced good.Therefore, when requiring good intensity and flexible balanced, if tissue is that bainite or ferrite and bainite get final product more than 90%.And, when above-mentioned steel are the non-hardened and tempered steel material, can be reduced to the big energy and the cost that carry out modifier treatment.
In order to make constituting by bainite or ferrite and bainite more than 90% of non-hardened and tempered steel material, steel disc with the chemical constitution of record in aforesaid (III), after for example being heated to 1050-1300 ℃, carry out hot-work such as heat forged, processing the back under the temperature more than 900 ℃ with the speed of cooling below 60 ℃/minute, can carry out air cooling or place cooling, till 300 ℃.
When the non-hardened and tempered steel material, the shaping during hot-work is bigger than more, organizes miniaturization, and intensity and flexible equilibrium are good more.For this reason, in the described hot-work of reality, be shaped than being to be ideal more than 1.5.Here " ratio is shaped " is meant with Ao to be the preceding sectional area of processing.A for processing after sectional area the time (Ao/A).
The crystal size of original austenite particulate is 4 when above by JIS granularity label in tissue, in the non-hardened and tempered steel material (that is, " steel of condition Y ") that constitutes by bainite or ferrite and bainite more than 90% of tissue, can guarantee to stablize good intensity and flexible equilibrium.At this, " the original austenite particulate " in the non-hardened and tempered steel material is meant to heat with the hot-work phase transformation and generates preceding austenite crystallite such as bainite and ferrite.Tissue more than 90% be the non-hardened and tempered steel material of bainite or ferrite and bainite the time, by corroding, observe with opticmicroscope and can easily judge former Ovshinsky particulate with nital.
After carrying out hot-work and cooling, under 200-700 ℃ of temperature,, can obtain intensity and the good especially steel of toughness equilibrium if carry out 20-150 minute heat treated.
At last, the tissue of steel be martensite more than 50% the time, intensity and flexible are balanced for better.Therefore, when requiring to have better intensity and flexible balanced, tissue should be martensite more than 50%.And, when described steel are modified steel, can obtain the equilibrium of very good strength and toughness.
For constituting by martensite more than 50% of the tissue that makes modified steel, the steel disc of the chemical constitution that will in (IV) that has stated, put down in writing, after for example being heated to 1050-1300 ℃, carry out hot-work such as heat forged by the ratio of the shaping more than 1.5, after processing under the temperature more than 900 ℃, with the speed of cooling below 60 ℃/minute, can carry out air cooling or place cooling, till 300 ℃.Then, be heated to 800-950 ℃ and keep after 20-150 minute, water or wet goods heat-eliminating medium quench, and further heat 400-700 ℃ and keep after 20-150 minute, carry out air cooling, place cooling with the speed of cooling more than 2 ℃/minute, according to circumstances also can carry out water-cooled, oil cooling.As quench treatment, after hot-work, by austenite field or austenite and ferritic two-phase field direct quenching, also available what is called " direct quenching ".
In order to make the equilibrium of very excellent strength and toughness, more stablely guarantee modified steel, its tissue be ideal for martensite more than 80%.Also have, nubbin beyond the martensite in tissue is the tempered tissue of ferrite when quench treatment is quenched by the tempered tissue of ferrite, perlite and bainite of austenite phase transformation with by austenite and ferritic two-phase field, and does not also have the tempered tissue of the remaining austenite of phase transformation (so-called " remaining austenite ") through quench treatment.In fact, 100% of tissue also can be martensite.
The crystal size of original austenite particulate is 5 when above by JIS granularity label, and the modified steel that are made of martensite more than 50% of tissue (that is, " steel of condition Z ") can be guaranteed highly stable good intensity and flexible equilibrium.Here, " the original austenite particulate " in modified steel is the original austenite particulate before quenching.Tissue be martensitic modified steel more than 50% the time, for example, behind the quenching steel, perhaps behind the Q-tempering steel, cut out the examination material, corrode,, can judge this original austenite particulate easily by using observation by light microscope with the aqueous solution of bitter taste acids of interpolation tensio-active agent.
Below by embodiment, the present invention is described more specifically, but the invention is not restricted to these embodiment.
Embodiment 1
Steel with chemical constitution shown in the table 1-4 melts with 150kg vacuum melting stove or 3 tons of vacuum melting stoves.With the fusing of 3 tons of vacuum melting stoves be steel 1, steel 6 and steel 36-40, the steel that other all use 150kg vacuum melting stove to melt.In addition, except that steel 36 and 38, generate,,, add Ti at last, so adjust the size and the purity of the carbon sulfide of Ti having added various elements with Si and the abundant deoxidation of Al for preventing the Ti oxide compound.For steel 36 and steel 38, in the time of with Si and Al deoxidation, add Ti.
Steel 1-36 chemical constitution in table 1-3 is the steel of the embodiment of the invention in the specialized range of the present invention.On the other hand, any one of each element of steel 37-46 in table 4 is the steel of the comparative example beyond regulation content range of the present invention.
Secondly, these steel are heated to 1250 ℃ after, 1000 ℃ of heat forged of processing, make the pole of diameter 60mm.In addition, be that cooling conditions after 5-35 ℃/minute the heat forged carries out air cooling or placement is cooled to 300 ℃ with the speed of cooling, the tissue of adjusting pole makes tensile strength be approximately 845-870MPa.And for steel 6, steel 7, steel 9, steel 11, steel 29-36, steel 40, steel 45 and steel 46, after carrying out the cooling after the heat forged, be heated to 770-900 ℃ after 1 hour, carry out water quenching, carry out temper (being cooled to after the tempering air cooling) at 550-560 ℃, adjust tissue and strength level.
(R/2 part position, position from the 15mm on the pole surface of such gained, R is the radius of pole), gather JIS14A tension test sheet, (diameter of parallel portion is 8mm to little wild formula rotating bending test sheet, its length is 18.4mm) and JIS3 shock test sheet (2mmU otch pendulum test film), tensile strength, fatigue strength (limit of fatigue) and toughness (impact value) studied in room temperature.
R/2 part position with the pole surface is the center, Fig. 3 acquisition test sheet according to JISG0555, with magnification is that the width that 400 times opticmicroscope 60 visual fields are observed through mirror ultrafinish is 15mm, it highly is the detection faces of 20mm, the limit distinguishes carbon sulfide and other inclusiones of Ti, and its purity is measured on the limit.The maximum diameter of the carbon sulfide of Ti is that 400 times opticmicroscope 60 visual fields are observed and to be measured with magnification also.After this, further with nital corrosion detection faces, be that 100 times opticmicroscope is observed with magnification through mirror ultrafinish, carry out the structure observation of R/2 part position, investigate ratio (area ratio) of each tissue.
By bit bore test the having carried out evaluation of machinability.That is to say that with the circle section that the pole of diameter 60mm is cut into 55mm length, in the hole that length direction is opened degree of depth 50mm, because the abrasion of sword end, the hole count in the time of can not holing is investigated machinability as the machinability evaluation number.Borehole conditions is used the straight-bar drill bit of JIS rapid tool steel SKH59 φ 6mm, and to give 0.20mm/rev, revolution 980rpm condition is carried out with soluble oil.
In described various test-results shown in the table 5-8.In addition, in 5-8, also put down in writing condition in the lump about the quenching and tempering of steel 6, steel 7, steel 9, steel 11, steel 29-36, steel 40, steel 45 and steel 46.
5-8 can find out by table, contain C, S, Ti and N in scope given to this invention, and the maximum value of the carbon sulfide of the Ti in the steel is below the 10 μ m, and when its purity was test sequence number 1-35 0.05% or more, the machinability evaluation number was above 200.Relative therewith, in test during sequence number 36, make content for C, S, Ti and the N of the steel 36 of test steel in the scope of the present invention's regulation, because the purity of the carbon sulfide of Ti drops to below 0.05%, the machinability evaluation number is low to be 51.In test sequence number 37,39 and 40 o'clock and since do for the test steel 37, any one all beyond the scope of the present invention's regulation, so the machinability evaluation number is low, is respectively 58,40,45 in the content of C, S, Ti and the N of steel 39 and steel 40.In the test sequence number is 38 o'clock, make S content for the steel 38 of test steel outside the scope of the present invention's regulation, and because the purity of the carbon sulfide of Ti also is lower than 0.05%, the machinability evaluation number is low to be 31.
Thus, when the almost equal evaluation machinability of tensile strength level, the excellent in machinability of steel involved in the present invention is fairly obvious.
On the other hand, depart from the steel 41-46 of scope of regulation of the present invention respectively as the time at the content of Nd, Se, Te, Ca, Pb, Bi for the sequence number 41-46 of test, its machinability is good, but with each amount of above-mentioned element the steel 2-7 of the scope of the present invention's regulation as for the test sequence number 2-7 of test steel the time relatively, it also is tangible that its fatigue strength and/or toughness degenerate.
In addition, with table 5-8, can find out significantly that also in situation of the present invention, the maximum diameter of the carbon sulfide of Ti is 0.5-7 μ m, purity is 0.08-0.2%, machinability and fatigue strength balanced good; And, tissue be bainite more than 90%, or when ferrite and bainite, intensity and flexible equilibrium become well, tissue be martensite more than 50% the time, intensity and flexible equilibrium are very good.
Embodiment 2
With the steel 47-54 of the chemical constitution shown in the table 9, be to melt with 150kg vacuum melting stove or 3 tons of vacuum melting stoves.With the fusing of 3 tons of vacuum melting stoves be steel 47-49, other all use 150kg vacuum melting stove to melt.In addition, generate,, adding various elements with Si and the abundant deoxidation of Al in order to prevent the Ti oxide compound, last, add Ti, adjust the size and the purity of the carbon sulfide of Ti.Any chemical group Chengdu of steel 47-54 in table 9 is the steel of the embodiment of the invention in the scope of the present invention's regulation.
Secondly, these steel are heated to 1250 ℃ after, 1000 ℃ of heat forged of processing, make the pole of diameter 60mm.In addition, be that cooling conditions after 5-35 ℃/minute the heat forged carries out air cooling or placement is cooled to 400 ℃ with the speed of cooling, organize mainly to constitute by ferrite, perlite, adjust tensile strength.
Identical by resulting like this pole with the situation of embodiment 1, gather various test films and examine or check.That is to say, surperficial R/2 part position from pole, gather JIS14A tension test sheet, (diameter of parallel portion is 8mm to little wild formula rotating bending test sheet, its length is 18.4mm) and JIS3 shock test sheet (2mmU otch pendulum test film), tensile strength, fatigue strength (limit of fatigue) and toughness (impact value) investigated in room temperature.
To be the center from the R/2 part position on pole surface, Fig. 3 acquisition test sheet according to JISG0555, with magnification is that the width that 400 times opticmicroscope 60 visual fields are observed through mirror ultrafinish is 15mm, it highly is the detection faces of 20mm, carbon sulfide and other inclusiones with Ti distinguishes on one side, Yi Bian measure its purity.With times magnification is the maximum diameter that the carbon sulfide also measure Ti is observed in 400 times opticmicroscope 60 visual fields.After this, further with nital corrosion detection faces, be the structure observation that 100 times opticmicroscope carries out R/2 part position with magnification through mirror ultrafinish, investigate ratio (area ratio) of each tissue.The steel 51-53 of test sequence number 51-53 is tested steel as supplying, carry out the mensuration of the ferrite granularity label of JIS, produce electron scanning micrograph simultaneously, the mean value of pearlitic thin layer spacing is shown.
Also carried out evaluation by the machinability of bit bore test.Its test conditions and evaluation method be explanation in embodiment 1.
At table 10, show the result of above-mentioned various tests.
Can be found out significantly that by table 10 when the non-hardened and tempered steel material that is made of ferrite and perlite more than 90% of tissue, ferritic ratio is pressed area than being 20-70%, ferritic granularity is more than 5 by JIS granularity label.The mean value of pearlitic thin layer spacing is below the 0.2 μ m, if satisfy an above-mentioned condition at least, can obtain good intensity and flexible equilibrium.And, with the value of the represented fn1 of described formula (1) when bigger and/or with the value of the represented fn2 of described formula (2) when bigger than 2 than 0%, the cutting index also becomes greatly, than 2 greatly the time, fatigue strength is also big in the value of the represented fn2 of the formula of using (2).
Embodiment 3
The steel 55-59 of the shown chemical constitution of table 11 founds with 150kg vacuum melting stove or 3 tons of vacuum melting stoves.Found steel 55 and steel 56 with 3 tons of vacuum melting stoves, other all use 150kg vacuum melting stove to found.In addition, in an embodiment, generate,, add after the various elements, add Ti, so adjust the size and the purity of the carbon sulfide of Ti with Si and the abundant deoxidation of Al in order to prevent the Ti oxide compound.Any chemical group Chengdu of steel 55-59 in the table 11 is the steel of the embodiment of the invention in the scope of the present invention's regulation.
Secondly, these steel are heated to 1250 ℃ after, 1000 ℃ of heat forged of processing, make the pole of diameter 60mm.In addition, be that cooling conditions after 5-35 ℃/minute the heat forged carries out air cooling or placement is cooled to 300 ℃ by speed of cooling, organize mainly by bainite or perlite and bainite to constitute, adjust tensile strength.In addition, after steel 57 and steel 58 carry out cooling after the heat forged, heat 1 hour ageing treatment of back air cooling at 560 ℃.
With identical, gather various test films and examine or check by the situation of resulting like this pole and embodiment 1.That is to say, surperficial R/2 part position by pole, gather JIS14A tension test sheet, (diameter of parallel portion is 8mm to little wild formula rotating bending test sheet, its length is 18.4mm) and JIS3 shock test sheet (2mmU otch pendulum test film), tensile strength, fatigue strength (limit of fatigue) and toughness (impact value) investigated in room temperature.
With the R/2 part position from the pole surface is the center, press Fig. 3 acquisition test sheet of JISG0555, with magnification is that the width that 400 times opticmicroscope 60 visual fields are observed through mirror ultrafinish is 15mm, it highly is the detection faces of 20mm, on one side the carbon sulfide of Ti and other inclusiones are distinguished, Yi Bian measure its purity.Be 400 times opticmicroscope 60 visual fields observation also, and studied the maximum diameter of the carbon sulfide of Ti with times magnification.After this, further with nital corrosion detection faces, be that 100 times opticmicroscope carries out the structure observation of R/2 part position with magnification, and investigated ratio (area compares) of each tissue through mirror ultrafinish.
Also carried out by bit bore test the having carried out evaluation of machinability.Test conditions and evaluation method are as described in the embodiment 1.
In table 12, go out the result of described various tests.In addition, in table 12, testing sequence number 60,61, also putting down in writing the condition of carrying out ageing treatment in the lump about steel 57, steel 58.
Can find out significantly by table 12, when the non-hardened and tempered steel material that constitutes by bainite or ferrite and bainite 90% or more of tissue, after carrying out hot-work and cooling off, carry out ageing treatment, obtain good strength and flexible equilibrium.And, with the value of the represented fn1 of described formula (1) when bigger and/or with the value of the represented fn2 of described formula (2) than 0% than 2 greatly the time, cut index and also become big.With the value of the represented fn2 of formula (2) than 2 greatly the time, fatigue strength is also big.
Embodiment 4
The steel 60-64 of the shown chemical constitution of table 13 founds with 150kg vacuum melting stove or 3 tons of vacuum melting stoves.Found steel 60 and steel 61 with 3 tons of vacuum melting stoves, other are founded with 150kg vacuum melting stove.In addition, in an embodiment also in order to prevent that the Ti oxide compound from generating, with Si and the abundant deoxidation of Al, add various elements after, add Ti, adjusted the size and the purity of the carbon sulfide of Ti.Any chemical group Chengdu of steel 60-64 in the table 13 is the steel of the embodiment of the invention in the scope of the present invention's regulation.
Secondly, these steel are heated to 1250 ℃ after, 1000 ℃ of heat forged of processing, make the pole of diameter 60mm.In addition, be that cooling conditions after 5-35 ℃/minute the heat forged carries out air cooling or placement is cooled to 300 ℃ with the speed of cooling.After this, be heated to 850-900 ℃ after 1 hour, use water quenching, carry out temper (being cooled to after the tempering air cooling) at 550 ℃, organize and the adjustment of strength level.
Identical from the pole that obtains like this with the situation of embodiment 1, gather various test films and investigate.Promptly, R/2 part position from the surface of pole, (diameter of parallel portion is 8mm to gather JIS14A tension test sheet and little wild formula rotating bending test sheet, its length is 18.4mm), and JIS3 shock test sheet (2mmU otch pendulum test film), investigated tensile strength, fatigue strength (limit of fatigue) and toughness (impact value) in room temperature.
With the R/2 part position from the pole surface is the center, press Fig. 3 acquisition test sheet of JISG0555, with magnification is that the width that 400 times opticmicroscope 60 visual fields are observed through mirror ultrafinish is 15mm, it highly is the detection faces of 20mm, on one side the carbon sulfide of Ti and other inclusiones are distinguished, Yi Bian measure its purity.Be 400 times opticmicroscope 60 visual fields observation also, and studied the maximum diameter of the carbon sulfide of Ti with times magnification.After this, further with nital corrosion detection faces, be 100 times observation by light microscope with magnification through mirror ultrafinish, observe the tissue of R/2 part position, and investigated ratio (area compares) of each tissue.
By bit bore test the having carried out evaluation of machinability.Test conditions and evaluation method are as described in the embodiment 1.
Result in various tests above-mentioned table 14 illustrate.In addition, in table 14, also put down in writing quenching and tempered condition in the lump about steel 60-64.
Can find out significantly by table 14, when the modified steel that constitute by martensite more than 50% of tissue, can obtain very good strength and flexible equilibrium.And, with the value of the represented fn1 of described formula (1) when bigger and/or with the value of the represented fn2 of described formula (2) than 0% than 2 greatly the time, cut index and also become big.With the value of the represented fn2 of formula (2) than 2 greatly the time, fatigue strength is also big.
Embodiment 5
In the embodiment 1-4 that has stated, after the part of steel 1, steel 6, steel 36-40, steel 47-49, steel 55, steel 56, steel 60 and the steel 61 that will found with 3 tons of vacuum melting stoves is heated to 1250 ℃, 1000 ℃ of heat forged processing of processing, place cool to room temperature, make the long square rod of 125mm.
Secondly, after these square rods were heated to 1250 ℃, processing temperature was carried out heat forged more than 1000 ℃, be cooled to 300 ℃ with cooling conditions air cooling after 5-35 ℃/minute the heat forged or placement, make the parts shape material of bent axle, machining is finished final bent axle.In addition, about the test sequence number 68,69,73,79 and 80, carry out the cooling of heat forged after, be heated to 850-900 ℃ after 1 hour, use water quenching, carry out the parts shape material that temper (air cooling that is cooled to after the tempering cools off) is made bent axle at 550 ℃, machining is made into final bent axle.
For the superhard cutting of handling with the symbol CNMG12041N-OX shape coating of JIS is used in the surfacing cut of being processed into the resultant articles shape, in dry type, cutting speed 100m/ branch, incision 1.5mm carries out under the condition of feeding 0.25mm/rev.After this, use the straight-bar drill bit of JIS rapid tool steel SKH59 φ 6mm, use soluble oil, carry out the oilhole processing of bent axle with feeding 0.20/rev, rotation number 980rpm condition.During by drill bit processing oilhole, estimate the machinability of entity with the radical of the bent axle of made because the abrasion of drill bit front edge can not be holed.
To do the center from the position of the 15mm on the surface of the pin portion (diameter 70mm) of the parts of above-mentioned bent axle, press Fig. 3 acquisition test sheet of JISG0555, with magnification is that the width that 400 times opticmicroscope 60 visual fields are observed through mirror ultrafinish is 15mm, it highly is the detection faces of 20mm, on one side the carbon sulfide of Ti and other inclusiones are distinguished, Yi Bian measure its purity.With magnification is 400 times opticmicroscope 60 visual fields observation, and has investigated the maximum diameter of the carbon sulfide of Ti.After this, further with nital corrosion detection faces, carry out structure observation with the opticmicroscope of 100 times of ratio of enlargement, and investigate ratio (area ratio) for tissue through mirror ultrafinish.And, being oriented to bent axle of test film to parallel direction, (diameter of parallel portion is 8mm to gather JIS14A tension test sheet and little wild formula rotating bending test sheet, its length is 18.4mm), and JIS3 shock test sheet (2mmU otch pendulum test film), and tensile strength, fatigue strength (limit of fatigue) and toughness (impact value) have been investigated in room temperature.
Result in various tests above-mentioned table 15 illustrate.In addition, also put down in writing in the lump about testing the quenching and the tempered condition of sequence number 68,69,73,79,80 at table 15.
Can find out significantly by table 15, good by the parts shape material cutting of the bent axle that relates to steel made of the present invention.And, to make the bent axle of parts raw material and compare to relate to steel of the present invention with the bent axle of making the parts raw material with the steel part of comparative example, the former intensity and flexible equilibrium are good.
Steel of the present invention, excellent in machinability, and have good intensity and flexible equilibrium is so can be used as with the automobile raw material of the various mechanical structures parts such as Transport Machinery, industrial machine, construction implement that are representative.By these steel are made raw material, carry out machining, can make the parts of various physical constructions with comparalive ease.
Table 1
Steel Chemical constitution (weight %) all the other: Fe and impurity
??C ??Si ??Mn ????P ????S ??Ti ????Al ????N ??Cu ??Ni ??Cr ??Mo ??V ??Nb ????B ?Nd ?Se ?Te ?Ca ?Pb ?Bi ?fn1 ?fn2 ?fn3
?1 ?2 ?3 ?4 ?5 ?6 ?7 ?8 ?9 10 11 12 0.48 0.23 0.37 0.47 0.39 0.27 0.41 0.30 0.23 0.45 0.23 0.25 0.47 0.21 0.21 0.43 0.11 0.23 0.70 1.52 0.48 0.04 0.80 0.01 0.85 1.60 1.01 0.83 0.98 0.78 0.87 0.76 1.86 1.14 1.02 2.16 0.020 0.020 0.021 0.020 0.020 0.019 0.019 0.018 0.019 0.020 0.020 0.019 0.055 0.012 0.157 0.012 0.114 0.161 0.063 0.050 0.069 0.010 0.146 0.015 0.09 0.06 0.81 0.16 0.40 0.86 0.20 0.66 0.24 0.61 0.22 0.56 0.020 0.021 0.019 0.018 0.021 ?0.021 0.021 0.020 0.021 0.021 0.021 0.020 0.0028 0.0015 0.0021 0.0019 0.0034 0.0023 0.0020 0.0013 0.0012 0.0034 0.0038 0.0038 ?- ?- ?- 0.02 ?- ?- ?- ?- ?- ?- 0.02 ??- ??- ??- ??- ??- ??- 0.15 ??- ??- ??- ??- ??- 0.05 0.50 0.22 ?- ?- 0.44 ?- ?- 0.27 ?- 1.15 ?- ??- ??- ??- ??- ??- 0.02 0.13 ??- ??- ??- 0.05 ??- ??- ??- 0.08 ??- 0.09 ??- 0.04 0.06 ??- ??- ??- ??- ??- ??- ??- 0.03 ??- ??- ??- ??- ??- ??- 0.04 ??- ??- ????- ????- ????- ????- ????- 0.0003 ????- ????- ????- ????- ????- ????- ??- 0.045 ??- ??- ??- ??- ??- 0.037 ??- ??- ??- ??- ??- ??- 0.17 ??- ??- ??- ??- ??- ??- ??- ??- ??- ??- ??- ??- 0.02 ??- ??- ??- ??- ??- ??- ??- ??- ??- ??- ??- ??- 0.003 ???- ???- ???- ???- ???- 0.003 ???- ??- ??- ??- ??- ??- 0.15 ??- ??- ??- ??- 0.12 ??- ??- ??- ??- ??- ??- ??- 0.12 ??- ??- ??- ??- 0.09 ?0.02 ?0.05 ?0.62 ?0.15 ?0.26 ?0.67 ?0.12 ?0.60 ?0.16 ?0.60 ?0.04 ?0.54 1.64 5.00 5.16 13.2 3.51 5.34 3.19 13.3 3.45 59.4 1.51 38.4 1.14 2.27 1.36 1.05 1.04 2.52 1.52 1.52 2.90 1.16 2.72 2.17
fn1=Ti(％)-1.2S(％)、fn2=Ti(％)/S(％) fn3=0.5Si(％)+Mn(％)+1.13Cr(％)+1.98Ni(％)
Table 2
Steel Chemical constitution (weight %) all the other: Fe and impurity
??C ??Si ??Mn ????P ????S ??Ti ??Al ??N ?Cu ?Ni ?Cr ?Mo ?V ?Nb ????B ????Nd ??Se ??Te ??Ca ??Pb ??Bi ??fn1 ??fn2 ??fn3
13 14 15 16 17 18 19 20 21 22 23 24 0.39 0.23 0.20 0.46 0.31 0.47 0.23 0.41 0.21 0.24 0.32 0.15 0.45 0.50 1.61 0.03 0.20 0.47 0.08 0.47 0.50 0.40 0.03 0.21 1.40 1.20 0.74 1.10 2.05 0.87 0.03 1.20 1.20 1.50 1.80 2.10 0.021 0.019 0.018 0.039 0.019 0.020 0.020 0.019 0.019 0.021 0.019 0.018 0.058 0.098 0.012 0.047 0.161 0.053 0.070 0.169 0.140 0.101 0.071 0.098 0.13 0.63 0.30 0.18 0.37 0.32 0.48 0.43 0.23 0.22 0.73 0.88 0.021 0.021 0.020 0.021 0.019 0.019 0.018 0.019 0.021 0.020 0.021 0.018 0.0022 0.0015 0.0032 0.0030 0.0036 0.0039 0.0014 0.0039 0.0035 0.0026 0.0039 0.0023 ??- ??- ??- ??- ??- ??- ??- 1.10 ??- ??- 0.20 ??- ??- ??- ??- ??- ??- ??- 0.02 ??- ??- ??- ??- ?0.02 ??- ??- 0.13 0.12 ??- 0.06 2.11 0.41 ??- 0.50 ??- 0.28 0.07 ??- ??- 0.54 ??- ??- ??- ??- ??- 0.08 ??- ??- ??- 0.13 0.08 ??- 0.03 ??- ??- ??- 0.31 ??- ??- ??- 0.04 ??- ??- ??- ??- ??- 0.06 ??- ??- ??- ??- ??- ??- ??- ??- ??- ??- 0.0003 ??- ??- ??- ??- ??- 0.0030 ???- ???- ???- ???- ???- ?0.048 ???- ???- ???- ???- 0.036 ???- 0.20 ??- ??- ??- 0.13 ??- ??- ??- ??- ??- ??- ??- ??- 0.03 ??- 0.02 ??- ??- ??- ??- ??- ??- ??- ??- ??- ??- ??- ??- ??- ??- 0.002 ??- ??- ??- ??- 0.002 ??- ??- ??- 0.07 ??- ??- ??- 0.11 ??- ??- ??- ??- ??- ??- ??- ??- ??- ??- ??- ??- ??- ??- ??- 0.11 0.06 0.51 0.29 ?- 0.12 0.18 0.26 0.39 0.23 0.06 0.10 0.64 0.76 2.19 6.41 26.3 ?- 3.83 2.30 6.01 6.81 2.55 1.64 2.18 10.2 8.95 1.63 1.45 1.69 ?- 1.25 2.15 1.17 2.49 1.90 1.45 2.27 1.82 2.56
fn1=Ti(％)-1.2S(％)、fn2=Ti(％)/S(％) fn3=0.5Si(％)+Mn(％)+1.13Cr(％)+1.98Ni(％)
Table 3
Steel Chemical constitution (weight %) all the other: Fe and impurity
??C ??Si ??Mn ????P ????S ??Ti ????Al ????N ???Cu ????Ni ??Cr ??Mo ??V ??Nb ????B ????Nd ??Se ??Te ??Ca ??Pb ??Bi ??fn1 ??fn2 ??fn3
25 26 27 28 29 30 31 32 33 34 35 36 0.23 0.10 0.28 0.21 0.20 0.25 0.21 0.23 0.14 0.26 0.29 0.51 1.57 0.15 0.40 0.05 0.10 0.20 1.05 0.45 0.21 0.33 1.60 0.22 0.40 0.50 1.50 0.70 1.54 0.80 1.00 0.80 1.51 1.34 0.44 0.95 0.020 0.019 0.019 0.018 0.020 0.018 0.019 0.020 0.019 0.019 0.018 0.020 0.133 0.141 0.011 0.044 0.015 0.110 0.143 0.025 0.032 0.114 0.065 0.073 0.67 0.78 0.19 0.27 0.63 0.73 0.44 0.28 0.87 0.39 0.24 0.25 0.020 0.019 0.020 0.019 0.020 0.021 0.020 0.020 0.020 0.020 0.018 0.021 0.0032 0.0030 0.0025 0.0018 0.0022 0.0027 0.0015 0.0013 0.0031 0.0027 0.0018 0.0070 ??- ??- ??- ??- ??- 0.04 ??- ??- ??- ??- ??- 0.11 0.12 ??- ??- ??- ??- ??- 0.05 ??- ??- ??- 0.10 ??- 0.05 0.55 0.11 1.34 ?- 1.20 0.45 0.05 ?- 0.64 0.15 ?- ??- 0.51 ??- ??- 0.05 ??- ??- 0.20 0.04 ??- ??- ??- ??- 0.24 ??- ??- 0.07 ??- ??- 0.12 0.15 ??- 0.06 ??- ??- ??- 0.06 ??- ??- 0.07 ??- 0.02 ??- ??- ??- ??- ???- ???- 0.0011 ???- 0.0005 ???- ???- 0.0010 0.0009 ???- 0.0016 ???- ??- ??- ??- ??- ??- ??- ??- ??- ??- 0.038 ??- 0.050 ??- ??- ??- 0.12 ??- ??- ??- 0.21 ??- ??- ??- ??- 0.03 ?- ?- ?- ?- ?- ?- 0.02 ?- ?- ?- ?- ??- 0.003 ??- ??- ??- ??- 0.002 ??- ??- ??- ??- ??- ??- ??- 0.12 ??- ??- 0.14 ??- ??- ??- 0.06 ??- ??- ??- ??- ??- ??- ??- ??- ??- ??- ??- ??- 0.10 0.09 ?0.51 ?0.61 ?0.17 ?0.22 ?0.62 ?0.60 ?0.27 ?0.25 ?0.83 ?0.25 ?0.16 ?0.16 5.02 5.53 17.0 6.23 41.5 6.64 3.09 11.1 27.1 3.43 3.65 3.45 1.48 1.20 1.82 2.24 1.59 2.26 2.13 1.08 1.32 2.23 1.32 1.06
fn1=Ti(％)-1.2S(％)、fn2=Ti(％)/S(％) fn3=0.5Si(％)+Mn(％)+1.13Cr(％)+1.98Ni(％)
Table 4
Steel Chemical constitution (weight %) all the other: Fe and impurity
??C ??Si ??Mn ????P ????S ??Ti ????Al ????N ?Cu ?Ni ??Cr ??M0 ?V ?Nb ????B ????Nd ??Se ??Te ??Ca ??Pb ??Bi ??fn1 fn2 fn3
37 38 39 40 41 42 43 44 45 46 0.04 0.27 0.49 0.28 0.23 0.36 0.49 0.38 0.26 0.41 0.50 0.45 0.31 0.48 0.21 0.21 0.41 0.11 0.22 0.67 1.40 1.27 0.75 1.23 1.61 1.05 0.81 1.01 0.78 0.87 0.020 0.020 0.020 0.019 0.021 0.020 0.020 0.019 0.019 0.018 0.058 0.001 0.013 0.169 0.012 0.157 0.012 0.117 0.169 0.064 0.09 0.06 0.03 0.90 0.06 0.78 0.16 0.41 0.89 0.21 0.020 0.021 0.021 0.021 0.020 0.018 0.017 0.020 0.020 0.020 0.0029 0.0016 0.0020 0.0180 0.0014 0.0021 0.0019 0.0036 0.0022 0.0021 ??- ??- ??- ??- ??- ??- ??- 0.02 ??- ??- ??- ??- ??- ??- ??- ??- ??- ??- ??- 0.15 0.50 0.14 ??- 0.33 0.48 0.22 ??- ??- 0.47 ??- ??- ??- 0.05 ??- ??- ??- ??- ??- 0.04 0.14 0.15 0.03 ??- 0.12 ??- 0.07 ??- 0.10 ??- 0.03 ??- ??- ??- 0.06 ??- ??- 0.04 ??- ??- ??- ???- 0.0003 ???- ???- ???- ???- ???- ???- ?0.0003 ???- ??- ??- ??- ??- 0.120 ??- ??- ??- ??- ??- ??- ??- ??- 0.18 0.53 ??- ??- ??- ??- ?- 0.02 ?- ?- ?- 0.06 ?- ?- ?- ??- ??- 0.005 ??- ??- ??- 0.013 ??- ??- ?- ?- 0.16 ?- ?- ?- ?- 0.52 ?- ??- ??- ??- ??- ??- ??- ??- ??- 0.42 ??0.03 ??0.06 ?-0.02 ??0.70 ??0.27 ??0.25 ??0.83 ??0.25 ??0.16 ??0.16 1.64 60.0 2.31 3.45 3.09 11.1 27.1 3.43 3.65 3.45 2.22 1.65 0.91 1.47 2.13 1.08 1.32 2.23 1.32 1.06
Fn1=Ti (%)-1.2S (%), fn2=Ti (%)/S (%) fn3=0.5Si (%)+Mn (%)+1.13Cr (%)+1.98Ni (%) rolls off the production line and represents to depart from defined terms of the present invention
</entry></row></tbody></tgroup></table></tables>
</entry></row></tbody></tgroup></table></tables>
Table 7
The test sequence number Steel The carbon sulfide of Ti Tissue The character of machinery The Q-tempering condition
Maximum diameter (μ m) Purity (%) ??F ?(％) ??P ?(％) ??B ?(％) ?M (％) Tensile strength TS (MPa) Fatigue strength σ W (MPa) Endurance ratio σ w/TS Pendulum impact value (J/cm 2) The machinability evaluation number The Heating temperature of quenching (℃) The tempered Heating temperature (℃)
?25 ?26 ?27 ?28 ?29 ?30 ?31 ?32 ?33 ??25 ??26 ??27 ??28 ??29 ??30 ??31 ??32 ??33 ????6.2 ????7.3 ????1.4 ????2.2 ????5.8 ????6.8 ????3.9 ????2.3 ????8.2 ????0.36 ????0.42 ????0.12 ????0.16 ????0.34 ????0.39 ????0.25 ????0.16 ????0.46 ????0 ????0 ????0 ????6 ????0 ????0 ????0 ????0 ????0 ????0 ????0 ????0 ????0 ????0 ????0 ????0 ????0 ????0 ??100 ??93 ??95 ??94 ??24 ??24 ??40 ??21 ??34 ??0 ??7 ??5 ??0 ??76 ??76 ??60 ??79 ??66 ??854 ??865 ??863 ??860 ??868 ??866 ??861 ??867 ??869 ??397 ??405 ??394 ??390 ??440 ??456 ??434 ??439 ??438 ??0.46 ??0.47 ??0.46 ??0.45 ??0.51 ??0.53 ??0.50 ??0.51 ??0.50 ????89 ????83 ????83 ????82 ????104 ????103 ????103 ????104 ????101 ??319 ??302 ??303 ??311 ??321 ??326 ??313 ??307 ??313 ??- ??- ??- ??- ??890 ??900 ??880 ??830 ??850 ???- ???- ???- ???- ??550 ??550 ??550 ??550 ??550
* mark represents to depart from defined terms of the present invention, and in addition, the * label in steel represents to depart from the condition of chemical constitution of the present invention.</entry></row></tbody></tgroup></table></tables>
Table 9
Steel Chemical constitution (weight %) all the other: Fe and impurity
??C ??Si ??Mn ????P ????S ??Ti ????Al ????N ?Cu ?Ni ?Cr ?Mo ?V ?Nb ???B ????Nd ??Se ??Te ??Ca ??Pb ??Bi ??fn1 fn2 fn3
47 48 49 50 51 52 53 54 0.47 0.26 0.46 0.34 0.34 0.27 0.28 0.48 0.46 0.80 0.83 0.39 0.33 0.80 0.26 0.50 1.50 1.05 0.99 0.63 1.07 1.05 1.00 1.48 0.036 0.033 0.035 0.031 0.021 0.037 0.019 0.029 0.143 0.102 0.010 0.132 0.093 0.164 0.140 0.141 0.11 0.69 0.70 0.60 0.58 0.68 0.70 0.20 0.029 0.021 0.019 0.030 0.020 0.020 0.019 0.019 0.0039 0.0034 0.0036 0.0039 0.0014 0.0039 0.0035 0.0021 ??- 0.10 ??- 0.16 ??- ??- ??- ??- ?- ?- ?- ?- ?- ?- ?- ?- 0.50 0.21 0.50 ??- ??- 0.41 0.50 0.48 ????- 0.54 ????- ????- ????- ????- ????- ????- ??- 0.12 ??- 0.22 0.17 0.12 ??- ??- ??- ??- 0.04 ??- 0.04 ??- 0.04 ??- ??- ??- ??- ??- ??- ??- ??- ??- ????- ????- ????- 0.048 ????- 0.037 ????- ????- ??- 0.15 0.13 ??- ??- ??- ??- ??- ????- ????- 0.01 ????- ????- ????- ????- ????- 0.003 ??- ??- ??- 0.002 ??- 0.001 0.002 0.08 0.08 ??- ??- ??- 0.13 ??- 0.07 ??- ??- 0.04 ??- ??- ??- 0.09 ??- ?-0.06 ??0.57 ??0.69 ??0.44 ??0.47 ??0.48 ??0.53 ??0.03 0.77 6.76 70.0 4.55 6.24 4.15 5.00 1.42 2.30 1.69 1.97 0.83 1.24 1.91 1.70 2.27
fn1=Ti(％)-1.2S(％)、fn2=Ti(％)/S(％) fn3=0.5Si(％)+Mn(％)+1.13Cr(％)+1.98Ni(％)
In the mean value item of ferritic JIS granularity label item and pearlitic thin layer spacing, "-" symbolic representation not to be measured</entry></row></tbody></tgroup></table></tables>
Table 11
Steel Chemical constitution (weight %) all the other: Fe and impurity
??C ??Si ??Mn ??P ????S ??Ti ??Al ????N ?Cu ?Ni ?Cr ?Mo ?V ?Nb ????B ????Nd ??Se ??Te ??Ca ??Pb ??Bi ??fn1 fn2 fn3
55 56 57 58 59 0.07 0.12 0.10 0.22 0.11 1.28 0.81 1.16 0.34 1.18 2.41 1.75 1.34 2.45 1.30 0.032 0.020 0.020 0.019 0.015 0.080 0.157 0.161 0.007 0.158 0.89 0.32 0.15 0.29 0.21 0.020 0.021 0.019 0.020 0.015 0.0026 0.0039 0.0023 0.0032 0.0020 ?- ?- ?- ?- ?- ????- ????- ??1.06 ????- ??1.03 ??- 0.51 0.28 0.40 0.25 ??- ??- ??- 0.24 ??- ??- ??- ??- 0.05 ??- ??- ??- ??- 0.06 ??- ???- ???- 0.0014 ???- 0.0011 ???- 0.036 ???- 0.030 ???- ??- ??- ??- ??- ??- ??- ??- ??- ?0.03 ??- ??- ??- 0.002 ??- 0.002 ??- ??- ??- 0.07 ??- ??- ??- 0.11 ??- 0.08 ??0.79 ??0.13 ?-0.04 ??0.28 ??0.02 11.1 2.04 0.93 41.4 1.33 3.05 2.73 4.34 3.07 4.21
fn1=Ti(％)-1.2S(％)、fn2=Ti(％)/S(％) fn3=0.5Si(％)+Mn(％)+1.13Cr(％)+1.98Ni(％)
In test sequence number 60,61, what put down in writing in " Heating temperature of quenching " hurdle is " aging temperature "</entry></row></tbody></tgroup></table></tables>
Table 13
Steel Chemical constitution (weight %) all the other: Fe and impurity
??C ??Si ??Mn ????P ????S ??Ti ????Al ????N ?Cu ?Ni ?Cr ?Mo ?V ?Nb ????B ????Nd ??Se ??Te ??Ca ??Pb ??Bi ??fn1 fn2 fn3
60 61 62 63 64 0.36 0.31 0.20 0.20 0.33 1.28 1.22 0.93 1.17 1.32 1.06 1.14 1.13 1.34 1.11 0.020 0.020 0.021 0.018 0.015 0.087 0.165 0.192 0.025 0.091 0.05 0.61 0.54 0.35 0.12 0.020 0.021 0.021 0.021 0.025 0.0020 0.0027 0.0015 0.0013 0.0015 ??- ??- 0.70 ??- ??- ?- ?- ?- ?- ?- 0.20 1.04 0.80 0.B0 0.18 ??- ??- ??- 0.04 ??- ??- ??- ??- 0.17 ??- ?- ?- ?- ?- ?- 0.0003 ???- ???- ???- 0.0003 ????- 0.038 ????- ????- ????- ??- ??- ??- 0.21 ??- ??- ??- ??- 0.02 ??- ??- ??- 0.002 ??- ??- 0.08 0.14 ??- ??- 0.09 ??- ??- 0.05 ??- ??- ?-0.05 ??0.41 ??0.31 ??0.32 ??0.01 0.57 3.70 2.81 14.1 1.32 1.93 2.93 2.50 2.83 1.97
fn1=Ti(％)-1.2S(％)、fn2=Ti(％)/S(％) fn3=0.5Si(％)+Mn(％)+1.13Cr(％)+1.98Ni(％)
</entry></row></tbody></tgroup></table></tables>
* mark represents to depart from defined terms of the present invention, and in addition, the * label in steel represents to depart from the condition of chemical constitution of the present invention.</entry></row></tbody></tgroup></table></tables>

Claims (19)

1, a kind of steel of excellent in machinability, it is characterized in that in the chemical constitution by weight that % contains that C:0.05-0.6%, S:0.002-0.2%, Ti:0.04-1.0%, N:0.008% are following, Nd:0-0.1%, Se:0-0.5%, Te:0-0.05%, Ca:0-0.01%, Pb:0-0.5%, Bi:0-0.4%, the maximum diameter of the carbon sulfide of the Ti in the steel is below the 10 μ m, and its purity is more than 0.05%.
2, steel according to claim 1, it is characterized in that the maximum diameter of the carbon sulfide of Ti is 0.5-7 μ m, and its amount is 0.08-2.0% by purity.
3, steel according to claim 1 and 2, what it is characterized in that organizing is ferrite and perlite more than 90%.
4, steel according to claim 1 and 2, what it is characterized in that organizing is bainite or ferrite and bainite more than 90%.
5, steel according to claim 1 and 2, what it is characterized in that organizing is martensite more than 50%.
6, non-hardened and tempered steel material according to claim 1, it is characterized in that containing that C:0.2-0.6%, Si:0.05-1.5%, Mn:0.1-2.0%, P:0.07% are following, S:0.01-0.2%, Al:0.002-0.05%, Cu:0-1.0%, Ni:0-2.0%, Cr:0-2.0%, Mo:0-0.5%, V:0-0.3%, Nb:0-0.1%, the chemical constitution that all the other are made of Fe and unavoidable impurities, and its tissue is ferrite and perlite more than 90%.
7, non-hardened and tempered steel material according to claim 6, the maximum diameter that it is characterized in that the carbon sulfide of Ti are that 0.5-7 μ m and its amount are 0.08-2.0 by purity.
8, according to the non-hardened and tempered steel material of claim 6 or 7 described excellent in machinability, it is characterized in that satisfied at least, in area than ferritic ratio be 20-70%, ferritic granularity by JIS granularity label be more than 5, the mean value of pearlitic thin layer spacing is a condition in below the 0.2 μ m.
9, according to the arbitrary described non-hardened and tempered steel material of claim 6-8, it is characterized in that at least satisfying bigger than 0% in order to the value of the represented fn1 of following formula (1), be in more than 2 one with the value of the represented fn2 of following formula (2):
fn1=Ti(％)-1．2S(％)????(1)；
fn2=Ti(％)／S(％)???????(2)。
10, non-hardened and tempered steel material according to claim 1, it is characterized in that containing C:0.05-0.3%, Si:0.05-1.5%, Al:0.002-0.05%, Cu:0-1.0%, Mo:0-0.5%, V:0-0.30%, Nb:0-0.1%, B:0-0.02%, value with the represented fn3 of following (3) formula satisfies 2.5-4.5%, the chemical constitution that all the other are made of iron and unavoidable impurities, and, its tissue be bainite more than 90%, perhaps be ferrite and bainite:
fn3=0．5Si(％)+Mn(％)+1．13Cr(％)+1．98Ni(％)????(3)
11, non-hardened and tempered steel material according to claim 10, the maximum diameter that it is characterized in that the carbon sulfide of Ti are 0.5-7 μ m, and its amount is 0.08-2.0% by purity.
12, according to claim 10 or 11 described non-hardened and tempered steel materials, it is characterized in that at least satisfying bigger than 0% in order to the value of the represented fn1 of following formula (1), be in more than 2 one with the value of the represented fn2 of following formula (2):
fn1=Ti(％)-1．2S(％)????(1)；
fn2=Ti(％)／S(％)???????(2)。
13, modified steel according to claim 1, it is characterized in that containing C:0.1-0.6%, Si:0.05-1.5%, Mn:0.4-2.0%, Al:0.002-0.05%, Cu:0-1.0%, Ni:0-2.0%, Cr:0-2.0%, Mo:0-0.5%, V:0-0.3%, Nb:0-0.1%, B:0-0.02%, the chemical constitution that all the other are made of Fe and unavoidable impurities, and, its tissue be martensite more than 50%.
14, modified steel according to claim 13, the maximum diameter that it is characterized in that the carbon sulfide of Ti are 0.5-7 μ m, and its amount is 0.08-2.0% by purity.
15, according to claim 13 or 14 described modified steel, it is characterized in that at least satisfying bigger than 0% in order to the value of the represented fn1 of following formula (1), be in more than 2 one with the value of the represented fn2 of following formula (2):
fn1=Ti(％)-1．2S(％)????(1)；
fn2=Ti(％)／S(％)???????(2)。
16, a kind of parts that become through machining are as material with the described steel of claim 1.
17, a kind of parts that become through machining are as material with the described non-hardened and tempered steel material of claim 6.
18, a kind of parts that become through machining are as material with the described non-hardened and tempered steel material of claim 10.
19, a kind of parts that become through machining are as material with the described modified steel of claim 13.
CN97191416A 1996-11-25 1997-11-25 Steel having excellent machinability and machined component using said steel Expired - Lifetime CN1095503C (en)

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JP313673/96 1996-11-25
JP31367396 1996-11-25
JP00197497A JP3494271B2 (en) 1997-01-09 1997-01-09 Free-cutting non-heat treated steel with excellent strength and toughness
JP1974/97 1997-01-09
JP16047/97 1997-01-30
JP01604797A JP3534146B2 (en) 1997-01-30 1997-01-30 Non-heat treated steel excellent in fatigue resistance and method for producing the same
JP4306297 1997-02-27
JP43138/97 1997-02-27
JP43062/97 1997-02-27
JP04313897A JP3489376B2 (en) 1997-02-27 1997-02-27 High-strength, high-toughness free-cut non-heat treated steel
JP7736997 1997-03-28
JP7734697 1997-03-28
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JP77369/97 1997-03-28

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