WO2012073485A1 - Acier de cémentation possédant une excellente forgeabilité à froid et procédé de production de ce dernier - Google Patents

Acier de cémentation possédant une excellente forgeabilité à froid et procédé de production de ce dernier Download PDF

Info

Publication number
WO2012073485A1
WO2012073485A1 PCT/JP2011/006655 JP2011006655W WO2012073485A1 WO 2012073485 A1 WO2012073485 A1 WO 2012073485A1 JP 2011006655 W JP2011006655 W JP 2011006655W WO 2012073485 A1 WO2012073485 A1 WO 2012073485A1
Authority
WO
WIPO (PCT)
Prior art keywords
less
steel
ferrite
mass
carburizing
Prior art date
Application number
PCT/JP2011/006655
Other languages
English (en)
Japanese (ja)
Inventor
克行 一宮
三田尾　眞司
Original Assignee
Ｊｆｅスチール株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ｊｆｅスチール株式会社 filed Critical Ｊｆｅスチール株式会社
Priority to KR1020137010303A priority Critical patent/KR101631521B1/ko
Priority to CN201180048735.6A priority patent/CN103154293B/zh
Priority to US13/821,763 priority patent/US20130186522A1/en
Publication of WO2012073485A1 publication Critical patent/WO2012073485A1/fr

Links

Images

Classifications

    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/06—Surface hardening
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • C21D1/32—Soft annealing, e.g. spheroidising
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/32—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for gear wheels, worm wheels, or the like
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/02—Making non-ferrous alloys by melting
    • 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
    • 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
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • 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
    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium with copper
    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/02—Pretreatment of the material to be coated
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
    • C23C8/20—Carburising
    • C23C8/22—Carburising of ferrous surfaces
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/80—After-treatment
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/009—Pearlite

Definitions

  • the present invention relates to a carburizing steel excellent in cold forgeability suitable for use in automobiles, various industrial equipment, and the like, and a method for producing the same.
  • gears used in automobiles and the like have been required to be reduced in size as the vehicle weight has been reduced due to energy saving, and the load on the gears has increased. Also, the load on the gears is increasing with the increase in engine output.
  • the durability of a gear is mainly determined by the bending fatigue failure of the tooth root and the surface pressure fatigue failure of the tooth surface.
  • gears have been manufactured by preparing gear materials using case-hardened steel specified as SCM420H, SCM822H, etc. in JIS G 4053 (2003), and subjecting the gear materials to surface treatment such as carburization.
  • surface treatment such as carburization.
  • the tooth root bending fatigue strength and pitting resistance can be reduced by changing steel materials, heat treatment methods, surface work hardening, etc. I tried to improve the sex.
  • Patent Document 1 while reducing Si in steel and controlling Mn, Cr, Mo and Ni, the grain boundary oxide layer on the surface after carburizing heat treatment is reduced, and the occurrence of cracks is reduced. Moreover, by suppressing the generation of an incompletely hardened layer, the reduction of surface hardness is suppressed to increase the fatigue strength, and further Ca is added to control the elongation of MnS that promotes the generation and propagation of cracks. Is disclosed.
  • Patent Document 2 discloses a method for increasing the temper softening resistance using a steel material to which Si is added in an amount of 0.25 to 1.50%.
  • Patent Document 1 since the grain boundary oxide layer and the incompletely hardened layer are reduced by reducing Si, it is possible to suppress the occurrence of bending fatigue cracks at the tooth root.
  • the temper softening resistance decreases only by simple Si reduction. As a result, temper softening due to frictional heat on the tooth surface cannot be suppressed, and the surface softens, so that pitching is likely to occur, and there is a problem that the occurrence of fracture shifts from the tooth base to the tooth surface side. .
  • Patent Document 2 the amount of Si is increased in order to increase the temper softening resistance. However, this increases the deformation resistance during cold working, and is unsuitable for use in cold forging.
  • Patent Document 3 an extra step of performing wire drawing before spheroidizing annealing is required, resulting in an increase in cost.
  • the form of the microstructure as it is rolled affects the structure and hardness after the spheroidizing heat treatment.
  • the control range for obtaining an appropriate spheroidized structure is narrow, so that it is difficult to obtain a stable structure.
  • the present invention has been developed in view of the above situation, and is suitable as a material for high-strength gears having higher bending fatigue strength at the root than conventional gears and excellent in surface fatigue properties, It is an object of the present invention to propose a carburizing steel that can obtain a spheroidized annealed structure relatively easily at low cost, has excellent cold forgeability, and can be mass-produced, and an advantageous manufacturing method thereof.
  • the inventors have obtained the following knowledge. a) By optimizing the amounts of Si, Mn, and Cr in the steel material, the resistance to temper softening is increased, and if this optimization prevents softening due to heat generation on the gear contact surface, cracks in the tooth surfaces that occur during gear drive Occurrence can be suppressed. b) For grain boundary oxide layers that can be the origin of bending fatigue and fatigue cracks, the growth direction of the grain boundary oxide layer is changed from the depth direction to the surface density increasing direction by adding a certain amount of Si, Mn and Cr. change. Therefore, since there is no oxide layer grown in the depth direction to be a starting point, it becomes difficult to be a starting point for bending fatigue and fatigue cracks.
  • Si, Mn and Cr are effective in improving the temper softening resistance and controlling the grain boundary oxide layer.
  • Si, Mn and Cr It is necessary to strictly control the content of Cr.
  • d) In order to promote spheroidization of carbide and improve cold forgeability, it is necessary to strictly control the contents of C, Si, Mn and Cr. In particular, a large amount of Cr is effective.
  • the spheroidizing heat treatment conditions shown in FIG. 1 are applied to a high temperature heated rolled material (1140 ° C., coarse ferrite-pearlite structure) and a low temperature heated rolled material (950 ° C. heated, fine ferrite-pearlite structure). I evaluated it. About this evaluation result, FIG. 2 shows the influence of the annealing holding temperature on the hardness after spheroidizing annealing.
  • the overall hardness is high and the region where the Vickers hardness is HV130 or less is a very narrow temperature. It turns out that it is realizable only in the range.
  • the annealing holding temperature is low, a low-temperature heated rolled material is advantageous.
  • the steel subjected to the experiment contains basic components that satisfy the requirements and suitable conditions described later.
  • the microstructure is influenced by the cold forgeability, but this microstructure is strongly influenced by the structure before annealing in addition to the above spheroidizing annealing conditions. That is, the pre-annealing structure was investigated with respect to the ferrite-pearlite structure fraction and the ferrite grain size.
  • FIG. 3 shows the control of the structure before spheroidizing annealing on the cold forgeability after spheroidizing treatment (765 ° C.-8 hours), specifically, the ferrite and pearlite. It was found that a steel material having excellent cold forgeability can be obtained by setting the total structural fraction to 85% or more and the average grain size of ferrite to 25 ⁇ m or less.
  • the limit upsetting rate is the upsetting rate when the column is upset by a press machine and a crack occurs at the end.
  • the steel composition is the same as in the experiment of FIG.
  • the present invention is based on the above findings.
  • the gist configuration of the present invention is as follows. 1. % By mass C: 0.1 to 0.35% Si: 0.01-0.22%, Mn: 0.3-1.5% Cr: 1.35 to 3.0% P: 0.018% or less, S: 0.02% or less, Al: 0.015-0.05% N: 0.008 to 0.015% and O: 0.0015% or less are contained within the range satisfying the following formulas (1), (2) and (3), the balance is the composition of Fe and inevitable impurities, and the steel structure Steel for carburization in which the total structural fraction of ferrite and pearlite is 85% or more and the average grain size of ferrite is 25 ⁇ m or less.
  • the above carburizing steel is subjected to cold forging which is processed into various parts shapes after carburizing treatment. Prior to this cold forging, it is preferable to perform spheroidizing annealing, but depending on the required amount of processing, etc., it may be subjected to cold forging without performing spheroidizing annealing.
  • the steel is further in mass%, Cu: 1.0% or less, Ni: 0.5% or less, Mo: 0.5% or less, Carburizing steel containing one or more selected from V: 0.5% or less and Nb: 0.06% or less.
  • a method for producing carburizing steel that is cooled at a low temperature. 3.1 ⁇ ⁇ ([% Si] / 2) + [% Mn] + [% Cr] ⁇ ⁇ 2.2 --- (1) [% C] - ([% Si] / 2) + ([% Mn] / 5) +2 [% Cr] ⁇ 3.0 --- (2) 2.5 ⁇ [% Al] / [% N] ⁇ 1.7 --- (3)
  • [% M] is the content of element M (% by mass)
  • the steel material is further in mass%, Cu: 1.0% or less, Ni: 0.5% or less, Mo: 0.5% or less, A manufacturing method of carburizing steel containing one or more selected from V: 0.5% or less and Nb: 0.06% or less.
  • carburizing steel excellent in not only the bending fatigue property of the tooth root but also the surface pressure fatigue property of the tooth surface is mass-produced in a process involving cold forging. Can be obtained at
  • Si 0.01-0.22%
  • Si is an element that increases the softening resistance in the temperature range of 200 to 300 ° C., which is expected to be reached during the rolling of gears and the like, and at least 0.01% addition is indispensable for exerting the effect. Preferably 0.03% or more is added.
  • Si is a ferrite stabilizing element, excessive addition raises the Ac 3 transformation point, and ferrite tends to appear in the core portion having a low carbon content in the normal quenching temperature range. , Leading to a decrease in strength. Excessive addition also has the disadvantage of hardening the steel material before carburizing and degrading the cold forgeability. In this respect, when the Si content is 0.22% or less, the above-described adverse effects do not occur, so the Si content is limited to a range of 0.01 to 0.22%. Preferably it is 0.03 to 0.22% of range.
  • Mn 0.3-1.5%
  • Mn is an element effective for hardenability, and requires addition of at least 0.3%.
  • Mn tends to form an abnormal carburizing layer, and excessive addition causes an excessive amount of retained austenite and leads to a decrease in hardness, so the upper limit was made 1.5%.
  • Preferably it is 0.4 to 1.2% of range. More preferably, it is in the range of 0.6 to 1.2%.
  • Cr 1.35 to 3.0% Cr is an element effective for improving not only hardenability but also temper softening resistance. However, if its content is less than 1.35%, its addition effect is poor. On the other hand, if it exceeds 3.0%, the effect of increasing the softening resistance is saturated, and rather, it becomes easier to form a carburized abnormal layer, so the Cr content is limited to the range of 1.35 to 3.0%. Preferably it is 1.35 to 2.6% of range.
  • P 0.018% or less P is segregated at the grain boundary and lowers the toughness of the carburized layer and the core. Therefore, the lower the content, the better, but 0.018% is acceptable. Preferably it is 0.016% or less. Usually, it is difficult to make the content 0%, but if possible, the content may be 0%.
  • S 0.02% or less S is an element that exists as sulfide inclusions and is effective in improving machinability. However, excessive addition causes a decrease in fatigue strength, so the upper limit was made 0.02%. From the viewpoint of machinability, 0.004% or more may be contained.
  • Al 0.015-0.05%
  • Al is an element which combines with N to form AlN and contributes to the refinement of austenite crystal grains. To obtain this effect, 0.015% or more, preferably 0.018% or more is required to be added. On the other hand, if the content exceeds 0.05%, the formation of Al 2 O 3 inclusions harmful to fatigue strength is promoted, so the Al content is limited to a range of 0.015 to 0.05%. Preferably it is 0.015 to 0.037% of range.
  • N 0.008 to 0.015%
  • N is an element that combines with Al to form AlN and contributes to the refinement of austenite crystal grains. Therefore, the appropriate addition amount is determined by the quantitative balance with Al, but 0.008% or more of addition is necessary to exert the effect. However, if added in excess, bubbles are generated in the steel ingot during solidification and deterioration of forgeability is caused, so the upper limit is made 0.015%. Preferably it is 0.010 to 0.015% of range.
  • O 0.0015% or less O is present as an oxide inclusion in steel and is an element that impairs fatigue strength. Therefore, the lower the content, the better, but 0.0015% is acceptable. Usually, it is difficult to make the content 0%, but if possible, the content may be 0%.
  • the above formula (1) is a factor that affects the hardenability and temper softening resistance. If the formula (1) is less than 2.2, the effect of improving the hardenability and temper softening resistance is not sufficient, and the fatigue strength is low. It becomes insufficient. On the other hand, if it exceeds 3.1, not only the above-mentioned improvement effect is saturated, but also cold workability is deteriorated.
  • the above formula (2) is a factor that affects the ease of spheroidizing of the carbide, and when the formula (2) satisfies 3.0 or more, the spheroidization becomes easy. By combining this composition with the knowledge of e and f, extremely excellent cold forgeability after spheroidizing annealing can be obtained.
  • the above equation (3) is a factor that affects the refinement of austenite crystal grains. If the value of the equation (3) is less than 1.7, the refinement effect is poor and the fatigue strength is insufficient. On the other hand, if it exceeds 2.5, the crystal grains easily become coarse and fatigue strength becomes insufficient, and workability is reduced due to solute Al and solute N.
  • Cu 1.0% or less Cu is effective in improving the strength of the base metal. However, if the content exceeds 1.0%, hot brittleness occurs and the surface properties of the steel deteriorate, so the content is made 1.0% or less.
  • a suitable addition amount is 0.01% or more.
  • Ni 0.5% or less Ni is effective in improving the strength and toughness of the base metal, but it is expensive.
  • a suitable addition amount is 0.01% or more.
  • Mo 0.5% or less Mo, like Ni, is effective in improving the strength and toughness of the base metal, but is included at 0.5% or less because it is expensive.
  • the content may be 0.2% or less.
  • a suitable addition amount is 0.05% or more.
  • V 0.5% or less
  • Si is an element useful for increasing the temper softening resistance. However, if the content exceeds 0.5%, the effect is saturated.
  • a suitable addition amount is 0.01% or more.
  • Nb 0.06% or less
  • Nb like V and Si, is an element useful for increasing the temper softening resistance. However, if the content exceeds 0.06%, the effect is saturated, so 0.06% or less.
  • a suitable addition amount is 0.007% or more.
  • the balance composition of the steel material is Fe and inevitable impurities.
  • B is not particularly added, but may be contained as an impurity as long as it is less than about 0.0003%.
  • the steel material having the above-mentioned preferred component composition is heated to 1160 ° C. or more and less than 1220 ° C., then rolled in a temperature range of Ar 3 points or more, temporarily cooled to 450 ° C. or less, and then 900 ° C.
  • the temperature range of 800-500 ° C is at a rate of 0.1-1.0 ° C / s. It is necessary to cool.
  • the steel material is heated to a temperature of 1160 ° C. or higher.
  • the heating temperature is set to less than 1220 ° C. because scale loss, surface property deterioration, fuel cost increase, and the like.
  • the hot working step preferably the hot rolling step, in order to break the cast structure and obtain a ferrite-pearlite structure, the working is finished at Ar 3 or higher and cooled to 450 ° C. or lower.
  • the hot working is performed at a reduction rate of 50% or more.
  • a lower limit for the cooling end temperature and a realistic value may be selected in consideration of the reheating cost. It is not necessary to provide an upper limit for the reduction ratio in hot working, and a realistic value may be selected in consideration of equipment load.
  • Step material reheating temperature Over 900 ° C and below 970 ° C
  • the second stage heating temperature is set to over 900 ° C. Preferably it is 920 degreeC or more.
  • Total rolling reduction in hot working 70% or more
  • the total rolling reduction ratio in hot working after reheating that is, the total rolling reduction ratio in the processing step after reheating is small, the crystal grains are coarse and the ferrite fraction after cooling is reduced. Not only is it easy to occur, but the hardness of the workpiece increases, so 70% or more.
  • the upper limit of the rolling reduction is not particularly required, and a realistic value may be selected in consideration of the equipment load.
  • this rolling reduction means the reduction rate of thickness when the steel material obtained by hot working is a plate, and the area reduction rate when it is a steel bar or wire.
  • the carburizing steel obtained by the above manufacturing method is preferably subjected to spheroidizing annealing and then subjected to cold forging.
  • the spheroidizing annealing is preferably performed at 760 to 820 ° C. for about 2 to 15 hours.
  • the present invention can obtain excellent cold forgeability even at a relatively low temperature spheroidizing annealing of about 740 to 760 ° C. it can.
  • the structure after spheroidizing annealing is a structure obtained by dividing and spheroidizing plate-like cementite in the layered pearlite of the previous structure.
  • the ground structure is ferrite, it retains the two-phase region of austenite and ferrite in the heating stage, and therefore generally inherits the previous structure.
  • the steel that has been cold forged into a predetermined part shape is subjected to carburizing heat treatment by a conventional method.
  • the surface of the member after the carburizing heat treatment has a structure mainly composed of martensite (tempered martensite when tempered).
  • Cold workability was evaluated by two items of a deformation resistance value and a limit upsetting rate. That is, the deformation resistance value was obtained by collecting a test piece having a diameter of 10 mm and a height of 15 mm from a position 1 / 4D from the surface of a rolled steel bar (diameter D), and using a 300 t (3000 kN) press machine. The compressive load at 70% upsetting was measured, and the deformation resistance measurement method by end face constrained compression proposed by the Japan Society for Technology of Plasticity was used.
  • the limit upsetting rate was defined as the upsetting rate when compression processing was performed by a method of measuring deformation resistance and a crack occurred at the end. If the deformation resistance value is 918 MPa or less and the limit upsetting rate is 76% or more, it can be said that the cold workability is good.
  • the spheroidizing heat treatment property was evaluated by three items: hardness after spheroidizing heat treatment, deformation resistance value, and limit upsetting rate. That is, in the same manner as the evaluation of cold workability in (2) above, a test piece having a diameter of 10 mm and a height of 15 mm was taken from a position 1 / 4D from the surface of the rolled steel bar (diameter D). After subjecting this test piece to spheroidizing heat treatment, the deformation resistance value and the limit upsetting rate were determined. The spheroidizing heat treatment was carried out under the two conditions (A) and (B) shown in FIG.
  • Carburized zone characteristics are 2 of the presence of coarse grains in the carburized zone and the grain boundary oxidation depth after carburizing at 930 ° C for 7 hours and carbon potential: 0.8%.
  • Grain boundary oxidation behavior was evaluated by observing the surface of the test piece after carburizing treatment with an optical microscope and measuring the grain boundary oxidation depth.
  • the present invention it is possible to provide a carburizing steel that is excellent in cold workability and excellent in rotational bending fatigue strength and surface pressure fatigue strength. Therefore, for example, when machined into gears, it is possible to obtain carburizing steel excellent in not only the bending fatigue characteristics of the tooth root but also the surface pressure fatigue characteristics of the tooth surface under mass production in the process involving cold forging. it can.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Heat Treatment Of Steel (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)

Abstract

L'invention concerne un acier de cémentation dont la composition, en termes de pourcentages en masse, est la suivante : de 0,1 à 0,35% de C, de 0,01 à 0,22% de Si, de 0,3 à 1,5% de Mn, de 1,35 à 3,0% de Cr, 0,018% au maximum de P, 0,02% au maximum de S, de 0,015 à 0,05% d'Al, de 0,008 à 0,015% de N et 0,0015% au maximum de O dans des plages qui répondent aux formules (1), (2) et (3), le reste étant constitué de Fe et des inévitables impuretés, la fraction structurelle totale de ferrite et de perlite dans la structure de l'acier s'élevant à 85% au moins et le diamètre moyen des particules de ferrite étant inférieur ou égal 25 μm. 3,1 ≥ {([%Si]/2) + [%Mn] + [%Cr]} ≥ 2,2 --- (1) [%C] - ([%Si]/2) + ([%Mn]/5) + 2[%Cr] ≥ 3,0 --- (2) 2,5 ≥ [%Al] / [%N] ≥ 1,7 --- (3) Ici, [%M] représente la teneur (% en masse) d'un élément M.
PCT/JP2011/006655 2010-11-30 2011-11-29 Acier de cémentation possédant une excellente forgeabilité à froid et procédé de production de ce dernier WO2012073485A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
KR1020137010303A KR101631521B1 (ko) 2010-11-30 2011-11-29 냉간 단조성이 우수한 침탄용 강 및 그 제조 방법
CN201180048735.6A CN103154293B (zh) 2010-11-30 2011-11-29 冷锻性优异的渗碳用钢及其制造方法
US13/821,763 US20130186522A1 (en) 2010-11-30 2011-11-29 Carburizing steel having excellent cold forgeability and method of manufacturing the same

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP2010267779 2010-11-30
JP2010-267779 2010-11-30
JP2011218340 2011-09-30
JP2011-218340 2011-09-30

Publications (1)

Publication Number Publication Date
WO2012073485A1 true WO2012073485A1 (fr) 2012-06-07

Family

ID=46171457

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2011/006655 WO2012073485A1 (fr) 2010-11-30 2011-11-29 Acier de cémentation possédant une excellente forgeabilité à froid et procédé de production de ce dernier

Country Status (5)

Country Link
US (1) US20130186522A1 (fr)
JP (1) JP5927868B2 (fr)
KR (1) KR101631521B1 (fr)
CN (2) CN104630634B (fr)
WO (1) WO2012073485A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2014047419A (ja) * 2012-09-04 2014-03-17 Sanyo Special Steel Co Ltd 熱処理変形の小さい機械構造用鋼材
JP2015081367A (ja) * 2013-10-22 2015-04-27 株式会社神戸製鋼所 絞り加工性と浸炭熱処理後の表面硬さに優れる熱延鋼板
CN114574768A (zh) * 2022-03-15 2022-06-03 中新(重庆)超高强材料研究院有限公司 一种汽车用铌钒复合微合金化、高接触疲劳性能齿轮用钢及齿轮的制造方法

Families Citing this family (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6241136B2 (ja) * 2013-08-26 2017-12-06 新日鐵住金株式会社 肌焼鋼鋼材
JP6225613B2 (ja) * 2013-09-30 2017-11-08 新日鐵住金株式会社 肌焼鋼鋼材
JP6197761B2 (ja) * 2014-07-24 2017-09-20 Ｊｆｅスチール株式会社 冷間加工品の製造方法
JP2016098426A (ja) * 2014-11-26 2016-05-30 山陽特殊製鋼株式会社 浸炭肌で使用する耐ピッチング特性に優れた機械構造用肌焼鋼
JP2016169433A (ja) * 2015-03-13 2016-09-23 株式会社神戸製鋼所 冷間加工性と浸炭熱処理後の靱性に優れる浸炭用鋼板
JP6558016B2 (ja) * 2015-03-26 2019-08-14 日本製鉄株式会社 浸炭機械構造部品
KR101705168B1 (ko) * 2015-04-20 2017-02-10 현대자동차주식회사 내구성이 향상된 침탄 합금강 및 이의 제조방법
JP6319212B2 (ja) * 2015-07-09 2018-05-09 Ｊｆｅスチール株式会社 歯車部品および歯車部品の製造方法
JP6794012B2 (ja) * 2015-12-10 2020-12-02 山陽特殊製鋼株式会社 耐結晶粒粗大化特性、耐曲げ疲労強度および耐衝撃強度に優れた機械構造用鋼
US11591675B2 (en) 2017-02-20 2023-02-28 Nippon Steel Corporation Steel sheet and method for producing same
CN107217210A (zh) * 2017-07-27 2017-09-29 陈海燕 一种齿轮钢
CN108165883A (zh) * 2018-01-22 2018-06-15 弗兰德传动系统有限公司 20CrMnMo钢及其加工方法
JP7152832B2 (ja) * 2018-06-18 2022-10-13 株式会社小松製作所 機械部品
JP2019011510A (ja) * 2018-08-20 2019-01-24 株式会社神戸製鋼所 冷間加工性と浸炭熱処理後の靱性に優れる浸炭用鋼板
CN110846580B (zh) * 2019-12-05 2021-09-07 马鞍山钢铁股份有限公司 一种高Mo高性能Mn-Cr系风电输出齿轮用钢及其生产方法
CN113430461B (zh) * 2021-06-24 2022-05-17 马鞍山钢铁股份有限公司 一种Nb、V微合金化齿轮钢及其制备方法、热处理方法、渗碳处理方法和渗碳齿轮钢

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1112684A (ja) * 1997-06-19 1999-01-19 Kobe Steel Ltd 冷間鍛造用肌焼鋼
WO1999005333A1 (fr) * 1997-07-22 1999-02-04 Nippon Steel Corporation Acier cemente particulierement capable d'empecher la recristallisation secondaire des particules pendant la cementation, procede de fabrication, et matiere brute formee pour pieces cementees
JP2001303174A (ja) * 2000-04-26 2001-10-31 Nippon Steel Corp 結晶粒粗大化防止特性に優れた高温浸炭部品用素形材とその製造方法
WO2010082481A1 (fr) * 2009-01-16 2010-07-22 新日本製鐵株式会社 Acier de cementation, composant cemente, et procede de production d'acier de cementation
JP2010168628A (ja) * 2009-01-23 2010-08-05 Jfe Steel Corp 冷間鍛造性に優れた浸炭用鋼の製造方法
JP2010242209A (ja) * 2009-03-17 2010-10-28 Sanyo Special Steel Co Ltd 耐結晶粒粗大化特性に優れた機械構造用鋼及びその製造方法

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2945714B2 (ja) 1990-05-15 1999-09-06 日産自動車株式会社 高面圧歯車
JPH07122118A (ja) 1993-10-27 1995-05-12 Akira Suzuki 電導性有機超薄膜
US6264759B1 (en) * 1998-10-16 2001-07-24 Pohang Iron & Steel Co., Ltd. Wire rods with superior drawability and manufacturing method therefor
JP4392324B2 (ja) 2004-10-28 2009-12-24 株式会社神戸製鋼所 冷間鍛造用肌焼鋼の製造方法

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1112684A (ja) * 1997-06-19 1999-01-19 Kobe Steel Ltd 冷間鍛造用肌焼鋼
WO1999005333A1 (fr) * 1997-07-22 1999-02-04 Nippon Steel Corporation Acier cemente particulierement capable d'empecher la recristallisation secondaire des particules pendant la cementation, procede de fabrication, et matiere brute formee pour pieces cementees
JP2001303174A (ja) * 2000-04-26 2001-10-31 Nippon Steel Corp 結晶粒粗大化防止特性に優れた高温浸炭部品用素形材とその製造方法
WO2010082481A1 (fr) * 2009-01-16 2010-07-22 新日本製鐵株式会社 Acier de cementation, composant cemente, et procede de production d'acier de cementation
JP2010168628A (ja) * 2009-01-23 2010-08-05 Jfe Steel Corp 冷間鍛造性に優れた浸炭用鋼の製造方法
JP2010242209A (ja) * 2009-03-17 2010-10-28 Sanyo Special Steel Co Ltd 耐結晶粒粗大化特性に優れた機械構造用鋼及びその製造方法

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2014047419A (ja) * 2012-09-04 2014-03-17 Sanyo Special Steel Co Ltd 熱処理変形の小さい機械構造用鋼材
US20150218682A1 (en) * 2012-09-04 2015-08-06 Sanyo Special Steel Co., Ltd. Machine Structural Steel Material Having Low Heat-Treatment Deformation
JP2015081367A (ja) * 2013-10-22 2015-04-27 株式会社神戸製鋼所 絞り加工性と浸炭熱処理後の表面硬さに優れる熱延鋼板
WO2015060311A1 (fr) * 2013-10-22 2015-04-30 株式会社神戸製鋼所 Tôle d'acier laminée à chaud ayant une excellente dureté de surface après traitement thermique de cémentation au carbone et une excellente emboutissabilité
CN105658830A (zh) * 2013-10-22 2016-06-08 株式会社神户制钢所 拉伸加工性和渗碳热处理后的表面硬度优异的热轧钢板
CN114574768A (zh) * 2022-03-15 2022-06-03 中新(重庆)超高强材料研究院有限公司 一种汽车用铌钒复合微合金化、高接触疲劳性能齿轮用钢及齿轮的制造方法

Also Published As

Publication number Publication date
JP5927868B2 (ja) 2016-06-01
CN104630634A (zh) 2015-05-20
CN104630634B (zh) 2017-09-08
JP2013082988A (ja) 2013-05-09
CN103154293A (zh) 2013-06-12
US20130186522A1 (en) 2013-07-25
CN103154293B (zh) 2015-09-16
KR101631521B1 (ko) 2016-06-24
KR20130058069A (ko) 2013-06-03

Similar Documents

Publication Publication Date Title
JP5927868B2 (ja) 冷間鍛造性に優れた浸炭用鋼およびその製造方法
JP5332646B2 (ja) 冷間鍛造性に優れた浸炭用鋼の製造方法
JP4956146B2 (ja) 鍛造性と結晶粒粗大化防止特性に優れた肌焼鋼およびその製造方法並びに浸炭部品
JP4725401B2 (ja) 鋼製部品及びその製造方法
WO2015098106A1 (fr) Procédé de production de constituant en acier cémenté et constituant en acier cémenté
JP4464864B2 (ja) 耐結晶粒粗大化特性と冷間加工性に優れた軟化焼鈍の省略可能な肌焼用鋼
JP5742801B2 (ja) 熱間圧延棒鋼または線材
JP4464862B2 (ja) 耐結晶粒粗大化特性と冷間加工性に優れた軟化焼鈍の省略可能な肌焼用鋼
JP5332517B2 (ja) 浸炭用鋼の製造方法
JP4581966B2 (ja) 高周波焼入れ用鋼材
JP4687616B2 (ja) 鋼製の浸炭部品又は浸炭窒化部品
JP5652844B2 (ja) 高加工性浸炭用鋼板
JP2015166495A (ja) 冷間鍛造性および結晶粒粗大化抑制能に優れた肌焼鋼
JP4448047B2 (ja) 耐結晶粒粗大化特性と冷間加工性に優れ、軟化焼鈍の省略可能な肌焼用鋼
JP2006307272A (ja) 耐結晶粒粗大化特性と冷間加工性に優れた肌焼用鋼およびその製法
JP4464861B2 (ja) 耐結晶粒粗大化特性と冷間加工性に優れた肌焼用鋼
JP5332410B2 (ja) 浸炭用鋼材の製造方法
JP4488228B2 (ja) 高周波焼入れ用鋼材
JP5869919B2 (ja) 冷間加工性に優れた肌焼用条鋼
JP4556770B2 (ja) 浸炭用鋼およびその製造方法
JP6390685B2 (ja) 非調質鋼およびその製造方法
JP5912778B2 (ja) 耐剥離性および耐衝撃疲労特性に優れた歯車
JP2007002292A (ja) 軟窒化用非調質鋼
JP4411096B2 (ja) 球状化後の冷間鍛造性に優れた肌焼用鋼線材・棒鋼
WO2016158611A1 (fr) Acier de cémentation et pièce cémentée

Legal Events

Date Code Title Description
WWE Wipo information: entry into national phase

Ref document number: 201180048735.6

Country of ref document: CN

121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 11845775

Country of ref document: EP

Kind code of ref document: A1

WWE Wipo information: entry into national phase

Ref document number: 13821763

Country of ref document: US

ENP Entry into the national phase

Ref document number: 20137010303

Country of ref document: KR

Kind code of ref document: A

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 11845775

Country of ref document: EP

Kind code of ref document: A1