WO2014038548A1 - Machine structure steel material having low heat-treatment deformation - Google Patents

Machine structure steel material having low heat-treatment deformation Download PDF

Info

Publication number
WO2014038548A1
WO2014038548A1 PCT/JP2013/073681 JP2013073681W WO2014038548A1 WO 2014038548 A1 WO2014038548 A1 WO 2014038548A1 JP 2013073681 W JP2013073681 W JP 2013073681W WO 2014038548 A1 WO2014038548 A1 WO 2014038548A1
Authority
WO
WIPO (PCT)
Prior art keywords
hardness
distance
quenching
less
steel
Prior art date
Application number
PCT/JP2013/073681
Other languages
French (fr)
Japanese (ja)
Inventor
藤松　威史
盛彦 中崎
Original Assignee
山陽特殊製鋼株式会社
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 山陽特殊製鋼株式会社 filed Critical 山陽特殊製鋼株式会社
Priority to KR1020157006758A priority Critical patent/KR20150047524A/en
Priority to US14/425,420 priority patent/US20150218682A1/en
Publication of WO2014038548A1 publication Critical patent/WO2014038548A1/en

Links

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
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • 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
    • C21D9/28—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for plain shafts
    • 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
    • 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
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel 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
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • 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
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • 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
    • C21D2211/008—Martensite

Definitions

  • the present invention relates to machine structural steel used as power transmission parts such as gears and shafts used in automobiles, industrial machines, and the like, and more particularly to steel for machine structure with small heat treatment deformation.
  • heat treatment deformation It is known that deformation of a steel material (hereinafter referred to as “heat treatment deformation”) occurs due to heat treatment such as quenching. If there is such heat treatment deformation, the number of manufacturing processes will increase to correct the deformation, the defective part rate will increase if it cannot be corrected, or it will be caused by deformation when incorporated as a drive system part. There are adverse effects such as generating noise and vibration. Therefore, it is a very important problem in practice to keep the heat treatment deformation as small as possible.
  • this heat treatment deformation is considered to be influenced by many factors other than steel, such as part shape, influence of pre-heat treatment process, physical properties of refrigerants such as quenching oil, and non-uniform cooling. Has been. Therefore, attempts have been made to reduce heat treatment deformation by optimizing them in various ways. For example, as a material countermeasure, a method has been proposed in which a soft ferrite phase is precipitated in the core of a hardened steel material to reduce heat treatment strain (see, for example, Patent Document 1).
  • the means for promoting the heat transfer coefficient is due to the convection of the coating material that promotes cooling provided in the portion where cooling is delayed or the coolant formed around the portion where cooling is delayed,
  • the means for reducing the heat transfer rate is said to be glass wool or a heat insulating coating material covering a portion where cooling is likely to proceed.
  • the conventional method proposed above cannot always be a general purpose means. This is because, for example, in the technique of Patent Document 1, a soft phase having a low strength may be introduced into a part, and in the technique of Patent Document 2, the heat treatment furnace itself has to be changed. This is because the technique of Patent Document 3 is not necessarily a general-purpose means, for example, it requires processing for individual heat-treated parts.
  • the present inventors have secured a sufficient steel material strength without relying on the generation of a ferrite structure that is soft and may reduce the strength of the component, and under a general quenching technique such as oil quenching, Even if the cooling of the steel becomes non-uniform, we have conducted intensive research on steel that can keep heat treatment deformation small. As a result, the inventors reduced the heat treatment deformation by controlling the chemical composition of the steel, the martensite transformation start temperature (Ms point), and the hardenability measured by the Jominy one-side quenching method to an appropriate range. It was found that it can be suppressed.
  • Ms point martensite transformation start temperature
  • an object of the present invention is to provide a steel material that is made of mechanical structural steel used as a power transmission component such as a gear or a shaft used in automobiles, industrial machines, and the like, and has less heat treatment deformation.
  • a steel material for mechanical structure with small heat treatment deformation is in mass%, C: 0.20 to 0.30% Si: 0.10 to 1.50%, Mn: 0.10 to 1.20%, P: 0.030% or less, S: 0.030% or less, Cr: 1.30-2.50%, Cu: 0.30% or less, Al: 0.008 to 0.300%, O: 0.0030% or less, N: 0.0020 to 0.0300%
  • a mechanical structural steel comprising the balance Fe and inevitable impurities,
  • the martensitic transformation start temperature (Ms point) of the steel material made of the steel is 460 ° C.
  • J1.5 of the hardness at a distance of 1.5 mm from the quenching end of the steel material and J9 of the hardness at a distance of 9 mm measured by the Jominy type one-end quenching method for the steel material is in the range of 0.70 to 0.85
  • the value of (J11 / J1.5) calculated by the following equation (2) using J1.5 of hardness at a distance of 1.5 mm and J11 of hardness at a distance of 11 mm is 0.67 to 0.78. In the range of A machine structural steel material with small heat treatment deformation is provided.
  • the steel material for mechanical structure having a small heat treatment deformation is in mass%, C: 0.20 to 0.30% Si: 0.10 to 1.50%, Mn: 0.10 to 1.20%, P: 0.030% or less, S: 0.030% or less, Cr: 1.30-2.50%, Cu: 0.30% or less, Al: 0.008 to 0.300%, O: 0.0030% or less, N: 0.0020 to 0.0300% is contained, Furthermore, it contains one or two of Ni: 0.20 to 3.00% and Mo: 0.05 to 0.50%, It is a steel material made of mechanical structural steel consisting of the balance Fe and inevitable impurities, Furthermore, the martensitic transformation start temperature (Ms point) of this steel material is 460 ° C.
  • J1.5 of the hardness at a distance of 1.5 mm from the quenching end of the steel and J9 of the hardness at a distance of 9 mm measured by the Jominy one-end quenching method for this steel is in the range of 0.70 to 0.85
  • the value of (J11 / J1.5) calculated by the above equation (2) using J1.5 of the hardness at a distance of 1.5 mm and J11 of the hardness at a distance of 11 mm is 0.67-0.
  • a machine structural steel material with small heat treatment deformation is provided.
  • a steel material for machine structural use having a small heat treatment deformation, the steel material being in mass%, C: 0.20 to 0.30% Si: 0.10 to 1.50%, Mn: 0.10 to 1.20%, P: 0.030% or less, S: 0.030% or less, Cr: 1.30-2.50%, Cu: 0.30% or less, Al: 0.008 to 0.300%, O: 0.0030% or less, N: 0.0020 to 0.0300% is contained, Further, Ti contains 0.020 to 0.200% and Nb: 0.02 to 0.20% of one or two, It is a steel material made of mechanical structural steel consisting of the balance Fe and inevitable impurities, Furthermore, the martensitic transformation start temperature (Ms point) of this steel material is 460 ° C.
  • a steel material for machine structural use having a small heat treatment deformation, the steel material being in mass%, C: 0.20 to 0.30% Si: 0.10 to 1.50%, Mn: 0.10 to 1.20%, P: 0.030% or less, S: 0.030% or less, Cr: 1.30-2.50%, Cu: 0.30% or less, Al: 0.008 to 0.300%, O: 0.0030% or less, N: 0.0020 to 0.0300% is contained, Furthermore, it contains one or two of Ni: 0.20 to 3.00% and Mo: 0.05 to 0.50%, Further, Ti contains 0.020 to 0.200% and Nb: 0.02 to 0.20% of one or two, It is a steel material made of mechanical structural steel consisting of the balance Fe and inevitable impurities, Furthermore, the martensitic transformation start temperature (Ms point) of this steel material is 460 ° C.
  • J1.5 of the hardness at a distance of 1.5 mm from the quenching end of the steel and J9 of the hardness at a distance of 9 mm measured by the Jominy one-end quenching method for this steel is in the range of 0.70 to 0.85
  • the value of (J11 / J1.5) calculated by the above equation (2) using J1.5 of the hardness at a distance of 1.5 mm and J11 of the hardness at a distance of 11 mm is 0.67-0.
  • a machine structural steel material with small heat treatment deformation is provided.
  • a steel material for machine structural use having a small heat treatment deformation, the steel material being in mass%, C: 0.20 to 0.30% Si: 0.10 to 1.50%, Mn: 0.10 to 1.20%, P: 0.030% or less, S: 0.030% or less, Cr: 1.30-2.50%, Cu: 0.30% or less, Al: 0.008 to 0.300%, O: 0.0030% or less, N: 0.0020 to 0.0300% Ni: 0 to 3.00%, Mo: 0 to 0.50% Ti: 0 to 0.200%, Nb: 0 to 0.20% Comprising the balance Fe and inevitable impurities,
  • the steel material has a martensitic transformation start temperature (Ms point) of 460 ° C.
  • the ratio of the hardness J9 at a distance of 9 mm from the quenching end of the steel material to the hardness J1.5 at a distance of 1.5 mm from the quenching end of the steel material when measured by the Jomini type one-end quenching method is in the range of 0.70 to 0.85, and the distance from the quenching end of the steel to the hardness J1.5 at a distance of 1.5 mm from the quenching end of the steel
  • a steel material for machine structure having a ratio of hardness J11 at 11 mm (J11 / J1.5) in the range of 0.67 to 0.78 is provided.
  • the steel material does not substantially contain Ni, Mo, Ti and Nb or contains an inevitable impurity level.
  • the steel material includes one or two of Ni: 0.20 to 3.00% and Mo: 0.05 to 0.50% in mass%.
  • the steel material includes one or two of Ti: 0.020 to 0.200% and Nb: 0.02 to 0.20% by mass%.
  • the steel material is, by mass%, one or two of Ni: 0.20 to 3.00% and Mo: 0.05 to 0.50%, and Ti. : 0.020 to 0.200%, and Nb: 0.02 to 0.20%.
  • the steel material for mechanical structure with small heat treatment deformation according to the present invention is, in mass%, C: 0.20 to 0.30%, Si: 0.10 to 1.50%, Mn: 0.10 to 1.20%, P: 0.030% or less, S: 0.030% or less, Cr: 1.30 to 2.50%, Cu: 0.30% or less, Al: 0.008 to 0.300%, O: 0.00.
  • N 0.0020 to 0.0300%
  • Ni 0 to 3.00%
  • Mo 0 to 0.50%
  • Ti 0 to 0.200%
  • Nb 0 to 0.20%
  • C 0.20 to 0.30%
  • C is an element necessary for securing the strength after quenching and tempering of steel or the strength of the core after carburizing, quenching and tempering as mechanical structural parts, and is adjusted to a predetermined range in order to reduce heat treatment deformation. There is a need. If the C content is less than 0.20%, the strength cannot be ensured, and if it exceeds 0.30%, deformation due to heat treatment becomes too large. Therefore, the C content is set to 0.20 to 0.30%, preferably 0.22 to 0.27%.
  • Si 0.10 to 1.50%
  • Si is an element necessary for deoxidation and is an effective element for imparting necessary strength and hardenability to steel. However, if the Si content is less than 0.10%, the effect cannot be obtained, and if it exceeds 1.50%, the machinability is lowered. Therefore, the Si content is 0.10 to 1.50%, preferably 0.20 to 1.00%.
  • Mn 0.10 to 1.20%
  • Mn is an element necessary for ensuring hardenability. However, if the Mn content is less than 0.10%, sufficient effect on hardenability cannot be obtained, and if it exceeds 1.20%, the machinability is lowered. Therefore, the Mn content is 0.10 to 1.20%, preferably 0.20 to 0.80%, and more preferably 0.20 to 0.55%.
  • P 0.030% or less
  • P is an unavoidable element contained in scrap, but segregates at the grain boundary and lowers properties such as impact strength and bending strength. Therefore, the P content is 0.030% or less (including 0%), and typically exceeds 0 and is 0.030% or less.
  • S 0.030% or less S is an element that improves machinability, but generates MnS that is a non-metallic inclusion and lowers the toughness and fatigue strength in the transverse direction. Therefore, the S content is 0.030% or less (including 0%), and typically exceeds 0 and is 0.030% or less.
  • Cr 1.30-2.50% Cr is an element necessary for ensuring hardenability. However, if the Cr content is less than 1.30%, a sufficient effect on hardenability cannot be obtained. Therefore, the Cr content is set to 1.30 to 2.50%, preferably 1.50 to 2.25%.
  • Ni 0.20 to 3.00%
  • Ni is an optional element that improves hardenability and toughness, and in order to obtain the effect, addition of 0.20% or more is preferable. However, if the Ni content exceeds 3.00%, the workability is remarkably lowered and the cost is increased, so the content is made 3.00% or less. Therefore, the Ni content is set to 0.20 to 3.00%.
  • Mo 0.05 to 0.50% Mo is an optional element that improves hardenability and toughness, and 0.05% or more is preferable for obtaining the effect. However, if the Mo content exceeds 0.50%, the workability decreases. Therefore, the Mo content is set to 0.05 to 0.50%.
  • Cu 0.30% or less Cu is an inevitable element contained from scrap, but has aging properties and an effect of increasing strength. However, when the Cu content exceeds 0.30%, the hot workability is lowered. Therefore, the Cu content is set to 0.30% or less (including 0%), and typically exceeds 0 and is set to 0.30% or less.
  • Al 0.008 to 0.300%
  • Al is an element used as a deoxidizing material, and also binds to N and precipitates as AlN as will be described later, thereby bringing about an effect of suppressing grain coarsening. In order to obtain this effect, 0.008% or more of Al needs to be added. On the other hand, if Al is added in excess of 0.300%, large alumina inclusions are formed, and fatigue characteristics and workability are deteriorated. Therefore, the Al content is set to 0.008 to 0.300%, preferably 0.014 to 0.200%.
  • O 0.0030% or less
  • O is an element inevitably contained in steel. However, if O exceeds 0.0030%, workability and fatigue strength are reduced due to an increase in oxide. Therefore, the content of O is set to 0.0030% or less (including 0%), preferably 0.0020% or less (including 0%). Also, typically, it exceeds 0 and is 0.0030% or less, and desirably exceeds 0 and is 0.0020% or less.
  • N 0.0020 to 0.0300%
  • N is an element that finely precipitates as AlN or Nb nitride in the steel and has an effect of preventing the coarsening of crystal grains.
  • the N content is set to 0.0020 to 0.0300%, preferably 0.0020 to 0.0200%.
  • the N content is set to 0.0020 to 0.0100% in order to avoid a decrease in fatigue strength due to excessive TiN formation.
  • Ti 0.020 to 0.200%
  • Ti is an optional element that combines with C in the steel to form carbides finely and has the effect of preventing grain coarsening. To obtain this effect, 0.020% or more of Ti is added. It is preferable to do. On the other hand, if the Ti content exceeds 0.200%, the machinability is impaired. Therefore, the Ti content is set to 0.020 to 0.200%.
  • Nb 0.02 to 0.20%
  • Nb is an arbitrary element that forms carbides or nitrides and has an effect of preventing grain coarsening.
  • nano-order sized NbC or Nb (C, N) finely dispersed in steel suppresses the growth of crystal grains. If the Nb content is less than 0.02%, the effect cannot be obtained. If the Nb content exceeds 0.20%, the amount of precipitates becomes excessive and workability deteriorates. Therefore, the Nb content is 0.02 to 0.20%, preferably 0.02 to 0.12%.
  • Ms point 460 ° C. or less
  • the martensite transformation start temperature Ms point
  • the Ms point is restricted to 460 ° C. or lower, but preferably the Ms point is restricted to 450 ° C. or lower.
  • the heat treatment deformation means bending of the shaft-shaped part, falling of the gear teeth, or twisting.
  • the heat treatment deformation referred to here is the bending of the shaft-shaped part, the gear teeth falling or twisting after quenching, and the change in the dimension (length, diameter, thickness, etc.) of the part before and after quenching.
  • the deformation due to heat treatment is suppressed because the martensitic transformation starts from the difficult state.
  • the bainite transformation occurs excessively, so that the heat treatment deformation increases due to the influence of the bainite transformation itself, and if the hardenability is too high, the bainite structure relaxes the heat treatment deformation. It is considered that the deformation due to heat treatment is also increased due to the small amount.
  • the present invention has beneficial effects such as improvement of component yield, simplification and abolition of component correction processes, and omission of gear tooth grinding for noise and vibration countermeasures. Can do.
  • the comparative example No. 2 shown in Table 2 was used as a structural steel used as a power transmission component such as a gear or a shaft used in automobiles or industrial machines.
  • Steel consisting of 1 to 16 component compositions, the balance Fe and unavoidable impurities was melted in a vacuum induction melting furnace to obtain a 100 kg steel ingot.
  • these ingots of the present invention and comparative examples were heated at 1250 ° C. for 5 hours and then forged into a steel bar having a diameter of 32 mm.
  • normalizing was performed by heating and holding at 900 ° C. for 1.5 hours and then air cooling.
  • a test piece having a diameter of 20 mm and a length of 80 mm was produced from a steel bar having a diameter of 32 mm, and a groove having a depth of 5 mm, a width of 8 mm, and a length of 80 mm was applied to the side surface of the test piece.
  • the cooling rate was varied greatly depending on the portion in the test piece.
  • the length of the test piece was measured after the groove processing. Further, the radius and groove width were measured at each position of 2 mm, 20 mm from the end of the test piece, and 40 mm which is the center of the test piece length. Then, after carburizing these test pieces at 930 ° C., the temperature was lowered to 850 ° C. in the furnace, and further maintained for 1 hour, and then quenched into a quenching oil at 60 ° C. After quenching, the specimens that were sufficiently cooled were measured for the bend and length of the specimen and the radius and groove width at each position of 2 mm, 20 mm from the specimen edge, and 40 mm, which is the center of the specimen length.
  • the radius before and after the heat treatment at each position of the total three locations of 2 mm, 20 mm from the end of the test piece, and 40 mm which is the center of the length of the test piece, and the groove width dimension measurement result After obtaining the dimensional change amount of the groove width, the values obtained by subtracting the minimum value from the maximum value among the dimensional change amounts at the three locations are defined as the radius change amount and the groove width change amount, respectively. It was evaluated as an index of deformation.
  • a test piece having a diameter of 3 mm and a length of 10 mm is determined from the steel bar having a diameter of 32 mm after the above normalization, and the Ms point, which is the martensitic transformation start temperature of the steel material, is measured using a fully automatic transformation recording measuring device. did.
  • the Ms point in the present embodiment is measured and measured under the condition that the cooling process of the component is assumed.
  • the above-described grooved test piece having a diameter of 20 mm has an oil temperature of 60 ° C. Assuming oil quenching, the cooling rate during quenching was measured at 30 ° C./s.
  • test piece was prepared from the above-described forged steel bar with a diameter of 32 mm, and “steel hardenability test method (one end) specified in JIS G 0561”. The test was conducted under the conditions according to the quenching method) and evaluated.
  • Table 3 shows the Ms point measured for the steel of the present invention, J1.5 of the hardness at a distance of 1.5 mm, J9 of the hardness at a distance of 9 mm from the quenching end measured by the Jomini type one-end quenching method, and Each value of the hardness J11 at a distance of 11 mm, and the obtained (J9 / J1.5) value and (J11 / J1.5) value are shown.
  • the martensite transformation start temperature that is, the Ms point is in the range of 388 to 444 ° C.
  • (J9 / J1.5) of this steel material is represented by the following formula (1 ) Is in the range of 0.72 to 0.85
  • the value of formula (2) shown below in (J11 / J1.5) is in the range of 0.67 to 0.78
  • the bend after heat treatment Is 0.005 to 0.030 mm
  • the absolute value of the difference in length of the test piece before and after heat treatment is 0.003 to 0.023 mm
  • the amount of change in radius before and after heat treatment is 0.002 to 0.008 mm.
  • Table 4 shows the measured Ms point of the steel of the comparative example, J1.5 of the hardness (HRC) at a distance of 1.5 mm from the quenching end measured by the Jomini type one-end quenching method, and the hardness at a distance of 9 mm.
  • Jominy hardenability which is J9 of thickness (HRC) and J11 of hardness (HRC) at a distance of 11 mm, and the obtained values of (J9 / J1.5) and (J11 / J1.5) are shown. .
  • the composition range excluding unavoidable impurities other than Fe, Ni, and Mo of steel materials is shown in Table 1, Ms point is set to 388 to 444 ° C. below 460 ° C., and measured by Jomini type one-end quenching method
  • the value of (J9 / J1.5) calculated from the equation (1) is calculated within the range of 0.72 to 0.85 from the equation (2) (
  • the value of J11 / J1.5) in the range of 0.67 to 0.78 By setting the value of J11 / J1.5) in the range of 0.67 to 0.78, the bending of the test piece after the heat treatment is reduced to a small range of 0.005 to 0.030 mm, and the test piece before and after the heat treatment is further reduced.
  • the absolute value of the difference in length is in a small range of 0.003 to 0.023 mm, the change in radius before and after heat treatment is in a small range of 0.002 to 0.008 mm, and the change in groove width before and after heat treatment is 0. .Small range from 011 to 0.024mm It could be.
  • the bending of the test piece after the heat treatment is 0.050 to 0.090 mm, and all are larger than the steel of the inventive example.
  • these No. any one or more of the absolute value of the difference in length of the test pieces before and after the heat treatment, or the radius change amount and the groove width change amount before and after the heat treatment is the value of the present invention. Bigger than steel. Therefore, among the comparative examples, the bending of the test piece after the heat treatment, the absolute value of the difference in length of the test piece before and after the heat treatment, and the radius change amount and the groove width change amount before and after the heat treatment are all the same as the steel of the present invention example. There was no one equivalent.
  • the Ms point satisfies the claims of the present invention, and the values of (J9 / J1.5) and (J11 / J1.5) satisfy the claims of the present invention.
  • the bending of the test piece after the heat treatment, the absolute value of the difference in the length of the test piece before and after the heat treatment, and the radius change amount and the groove width change amount before and after the heat treatment are substantially smaller than those in the comparative example. Deformation is suppressed.
  • the steel material of the present invention is used after being tempered after being subjected to heat treatment with hardening for hardening parts such as carburizing and quenching.
  • the steel material according to the present invention is a steel material applicable to power transmission parts such as gears and shafts used in automobiles and industrial machines.

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)
  • Heat Treatment Of Articles (AREA)

Abstract

This steel material having low heat-treatment deformation comprises a machine structure steel used as components for motive power transmission such as gears or shafts used in automobiles, industrial machinery, or the like. The steel material comprising a machine structure steel containing, by mass%, 0.20-0.30% of C, 0.10-1.50% of Si, 0.10-1.20% of Mn, no greater than 0.030% of P, no greater than 0.030% of S, 1.30-2.50% of Cr, no greater than 0.30% of Cu, 0.008-0.300% of Al, no greater than 0.0030% of O, and 0.0020-0.0300% of N, the remainder comprising Fe and unavoidable impurities, has an Ms point of no greater than 460°C, a ratio (J9/J1.5) of the hardness (J9) at a distance of 9 mm from the quenched end of the steel material when measured by means of a Jominy end quenching method to the hardness (J1.5) at a distance of 1.5 mm of 0.70-0.85, and a ratio (J11/J1.5) of the hardness (J11) at a distance of 11 mm from the quenched end of the steel material to the hardness (1.5) at a distance of 1.5 mm of 0.67-0.78.

Description

熱処理変形の小さい機械構造用鋼材Machine structural steel with low heat treatment deformation 関連出願の相互参照Cross-reference of related applications
　この出願は、２０１２年９月４日に出願された日本国特許出願２０１２－１９３７６３号に基づく優先権を主張するものであり、その全体の開示内容が参照により本明細書に組み込まれる。 This application claims priority based on Japanese Patent Application No. 2012-193762 filed on September 4, 2012, the entire disclosure of which is incorporated herein by reference.
　本発明は、例えば、自動車や産業機械などに使用されるギヤやシャフトなどの動力伝達部品として用いられる機械構造用鋼に関し、特に熱処理変形の小さい機械構造用鋼に関する。 The present invention relates to machine structural steel used as power transmission parts such as gears and shafts used in automobiles, industrial machines, and the like, and more particularly to steel for machine structure with small heat treatment deformation.
　焼入れ等の熱処理によって鋼材の変形（以下「熱処理変形」という。）が発生することが知られている。こうした熱処理変形があると、その変形を矯正するために製造工程数が増えたり、矯正しきれない場合には部品不良率が増加したり、あるいは駆動系部品として組み込んだ場合に変形に起因して騒音や振動を発生させるといった悪影響がある。したがって、熱処理変形をできる限り小さく抑えることが実用上非常に重要な課題となっている。 It is known that deformation of a steel material (hereinafter referred to as “heat treatment deformation”) occurs due to heat treatment such as quenching. If there is such heat treatment deformation, the number of manufacturing processes will increase to correct the deformation, the defective part rate will increase if it cannot be corrected, or it will be caused by deformation when incorporated as a drive system part. There are adverse effects such as generating noise and vibration. Therefore, it is a very important problem in practice to keep the heat treatment deformation as small as possible.
　従来、この熱処理変形は、鋼材以外の要因として、部品形状、熱処理前工程の影響、焼入油などの冷媒の物性値、冷却の不均一性といった多数の要因にも影響を受けていると考えられてきた。そこで、それらを種々に適正化することにより熱処理変形の軽減が試みられている。例えば、材料対策として、焼き入れ鋼材の芯部に軟質のフェライト相を析出させて熱処理歪みを軽減する方法が提案されている（例えば、特許文献１参照。）。 Conventionally, this heat treatment deformation is considered to be influenced by many factors other than steel, such as part shape, influence of pre-heat treatment process, physical properties of refrigerants such as quenching oil, and non-uniform cooling. Has been. Therefore, attempts have been made to reduce heat treatment deformation by optimizing them in various ways. For example, as a material countermeasure, a method has been proposed in which a soft ferrite phase is precipitated in the core of a hardened steel material to reduce heat treatment strain (see, for example, Patent Document 1).
　また、冷却方法からのアプローチとして、従来型の油焼入れではなく、加圧ガス冷却を利用する方法が提案されている（例えば、特許文献２参照。）。また、熱伝達率を促進あるいは低減する手段を用いて被冷却物の均一冷却化を図る方法が提案されている（例えば、特許文献３参照。）。 Also, as an approach from the cooling method, a method using pressurized gas cooling instead of conventional oil quenching has been proposed (for example, see Patent Document 2). In addition, a method for achieving uniform cooling of an object to be cooled using means for promoting or reducing the heat transfer coefficient has been proposed (for example, see Patent Document 3).
　なお、特許文献３において、熱伝達率を促進する手段は、冷却が遅れる部位に設けられた冷却を促進する被膜材または冷却が遅れる部位の周りに形成された冷却剤の対流によるものであり、熱伝達率の低減手段は、冷却が進行しやすい部位を覆うグラスウールまたは断熱被膜材によるとされている。 In Patent Document 3, the means for promoting the heat transfer coefficient is due to the convection of the coating material that promotes cooling provided in the portion where cooling is delayed or the coolant formed around the portion where cooling is delayed, The means for reducing the heat transfer rate is said to be glass wool or a heat insulating coating material covering a portion where cooling is likely to proceed.
特開１９９７－１１１４０８号公報JP 1997-111408 A 特開２００８－１２１０６４号公報JP 2008-121064 A 特開２０１０－１７４２８９号公報JP 2010-174289 A
　しかしながら、上記で提案されている従来の方法は必ずしも汎用的な手段たり得なかった。なぜなら、たとえば特許文献１の技術では、部品内部に強度の低い軟質相が導入されてしまうことがあり、特許文献２の技術では、熱処理炉そのものを変更しなければならないものであった。また、特許文献３の技術では、個々の熱処理部品に対する処理が必要になることなど、必ずしも汎用的な手段とは言い難かったからである。 However, the conventional method proposed above cannot always be a general purpose means. This is because, for example, in the technique of Patent Document 1, a soft phase having a low strength may be introduced into a part, and in the technique of Patent Document 2, the heat treatment furnace itself has to be changed. This is because the technique of Patent Document 3 is not necessarily a general-purpose means, for example, it requires processing for individual heat-treated parts.
　一方、本発明者らは、軟質で部品強度を低下させかねないフェライト組織の生成に頼らずに十分な鋼材強度を確保したうえ、油焼入れなどの一般的な焼入れ手法のもとで、たとえ部品の冷却が不均一となる場合でも、熱処理変形が小さく抑えられる鋼に関して鋭意研究を行った。その結果、本発明者らは、鋼の化学成分、マルテンサイト変態開始温度（Ｍｓ点）、ジョミニー式一端焼入法により測定される焼入性を適切な範囲に制御することによって熱処理変形が小さく抑えられることを知見した。 On the other hand, the present inventors have secured a sufficient steel material strength without relying on the generation of a ferrite structure that is soft and may reduce the strength of the component, and under a general quenching technique such as oil quenching, Even if the cooling of the steel becomes non-uniform, we have conducted intensive research on steel that can keep heat treatment deformation small. As a result, the inventors reduced the heat treatment deformation by controlling the chemical composition of the steel, the martensite transformation start temperature (Ms point), and the hardenability measured by the Jominy one-side quenching method to an appropriate range. It was found that it can be suppressed.
　したがって、本発明の目的は、自動車や産業機械などに使用されるギヤやシャフトなどの動力伝達用の部品として用いられる機械構造用鋼からなる、熱処理変形の少ない鋼材を提供することである。 Therefore, an object of the present invention is to provide a steel material that is made of mechanical structural steel used as a power transmission component such as a gear or a shaft used in automobiles, industrial machines, and the like, and has less heat treatment deformation.
　本発明の一態様によれば、熱処理変形の小さい機械構造用鋼材であって、該鋼材が、質量％で、
　Ｃ：０．２０～０．３０％、
　Ｓｉ：０．１０～１．５０％、
　Ｍｎ：０．１０～１．２０％、
　Ｐ：０．０３０％以下、
　Ｓ：０．０３０％以下、
　Ｃｒ：１．３０～２．５０％、
　Ｃｕ：０．３０％以下、
　Ａｌ：０．００８～０．３００％、
　Ｏ：０．００３０％以下、
　Ｎ：０．００２０～０．０３００％
を含有し、残部Ｆｅおよび不可避不純物からなる機械構造用鋼であり、
　該鋼からなる鋼材のマルテンサイト変態開始温度（Ｍｓ点）が４６０℃以下であり、
　該鋼材についてジョミニー式一端焼入法により測定される鋼材の焼入端からの距離１．５ｍｍにおける硬さのＪ１．５および距離９ｍｍにおける硬さのＪ９を用いて、下記の式（１）により算出の（Ｊ９／Ｊ１．５）の値が０．７０～０．８５の範囲にあり、
　さらに距離１．５ｍｍにおける硬さのＪ１．５、および距離１１ｍｍにおける硬さのＪ１１を用いて下記の式（２）により算出の（Ｊ１１／Ｊ１．５）の値が０．６７～０．７８の範囲にある、
　熱処理変形の小さい機械構造用鋼材が提供される。
　ただし、
　（Ｊ９／Ｊ１．５）＝（ジョミニー式一端焼入法により測定される焼入端からの距離９ｍｍにおける硬さ）÷（ジョミニー式一端焼入法により測定される焼入端からの距離１．５ｍｍの硬さ）・・・式（１）
　（Ｊ１１／Ｊ１．５）＝（ジョミニー式一端焼入法により測定される焼入端からの距離１１ｍｍにおける硬さ）÷（ジョミニー式一端焼入法により測定される焼入端からの距離１．５ｍｍにおける硬さ）・・・式（２） According to one aspect of the present invention, a steel material for mechanical structure with small heat treatment deformation, the steel material is in mass%,
C: 0.20 to 0.30%
Si: 0.10 to 1.50%,
Mn: 0.10 to 1.20%,
P: 0.030% or less,
S: 0.030% or less,
Cr: 1.30-2.50%,
Cu: 0.30% or less,
Al: 0.008 to 0.300%,
O: 0.0030% or less,
N: 0.0020 to 0.0300%
A mechanical structural steel comprising the balance Fe and inevitable impurities,
The martensitic transformation start temperature (Ms point) of the steel material made of the steel is 460 ° C. or less,
Using the following formula (1), J1.5 of the hardness at a distance of 1.5 mm from the quenching end of the steel material and J9 of the hardness at a distance of 9 mm measured by the Jominy type one-end quenching method for the steel material. The calculated (J9 / J1.5) value is in the range of 0.70 to 0.85,
Furthermore, the value of (J11 / J1.5) calculated by the following equation (2) using J1.5 of hardness at a distance of 1.5 mm and J11 of hardness at a distance of 11 mm is 0.67 to 0.78. In the range of
A machine structural steel material with small heat treatment deformation is provided.
However,
(J9 / J1.5) = (hardness at a distance of 9 mm from the quenching end measured by the Jomini type one-end quenching method) ÷ (distance from the quenching end measured by the Jominy type one-end quenching method. 5mm hardness) ... Formula (1)
(J11 / J1.5) = (hardness at a distance of 11 mm from the quenching end measured by the Jomini type one-end quenching method) ÷ (distance from the quenching end measured by the Jominy type one-end quenching method. (Hardness at 5 mm) (2)
　本発明の好ましい一態様によれば、熱処理変形の小さい機械構造用鋼材であって、該鋼材が、質量％で、
　Ｃ：０．２０～０．３０％、
　Ｓｉ：０．１０～１．５０％、
　Ｍｎ：０．１０～１．２０％、
　Ｐ：０．０３０％以下、
　Ｓ：０．０３０％以下、
　Ｃｒ：１．３０～２．５０％、
　Ｃｕ：０．３０％以下、
　Ａｌ：０．００８～０．３００％、
　Ｏ：０．００３０％以下、
　Ｎ：０．００２０～０．０３００％を含有し、
　さらにＮｉ：０．２０～３．００％およびＭｏ：０．０５～０．５０％のうち１種または２種を含有し、
　残部Ｆｅおよび不可避不純物からなる機械構造用鋼からなる鋼材であり、
　さらに、この鋼材のマルテンサイト変態開始温度（Ｍｓ点）が４６０℃以下であり、
　この鋼材についてのジョミニー式一端焼入法により測定される鋼材の焼入端からの距離１．５ｍｍにおける硬さのＪ１．５および距離９ｍｍにおける硬さのＪ９を用いて上記の式（１）により算出の（Ｊ９／Ｊ１．５）の値が０．７０～０．８５の範囲にあり、
　さらに、距離１．５ｍｍにおける硬さのＪ１．５および距離１１ｍｍにおける硬さのＪ１１を用いて、上記の式（２）により算出の（Ｊ１１／Ｊ１．５）の値が０．６７～０．７８の範囲にある、
　熱処理変形の小さい機械構造用鋼材が提供される。 According to a preferred embodiment of the present invention, the steel material for mechanical structure having a small heat treatment deformation, the steel material is in mass%,
C: 0.20 to 0.30%
Si: 0.10 to 1.50%,
Mn: 0.10 to 1.20%,
P: 0.030% or less,
S: 0.030% or less,
Cr: 1.30-2.50%,
Cu: 0.30% or less,
Al: 0.008 to 0.300%,
O: 0.0030% or less,
N: 0.0020 to 0.0300% is contained,
Furthermore, it contains one or two of Ni: 0.20 to 3.00% and Mo: 0.05 to 0.50%,
It is a steel material made of mechanical structural steel consisting of the balance Fe and inevitable impurities,
Furthermore, the martensitic transformation start temperature (Ms point) of this steel material is 460 ° C. or less,
Using the above formula (1), J1.5 of the hardness at a distance of 1.5 mm from the quenching end of the steel and J9 of the hardness at a distance of 9 mm measured by the Jominy one-end quenching method for this steel. The calculated (J9 / J1.5) value is in the range of 0.70 to 0.85,
Further, the value of (J11 / J1.5) calculated by the above equation (2) using J1.5 of the hardness at a distance of 1.5 mm and J11 of the hardness at a distance of 11 mm is 0.67-0. In the range of 78,
A machine structural steel material with small heat treatment deformation is provided.
　本発明の他の一態様によれば、熱処理変形の小さい機械構造用鋼材であって、該鋼材が、質量％で、
　Ｃ：０．２０～０．３０％、
　Ｓｉ：０．１０～１．５０％、
　Ｍｎ：０．１０～１．２０％、
　Ｐ：０．０３０％以下、
　Ｓ：０．０３０％以下、
　Ｃｒ：１．３０～２．５０％、
　Ｃｕ：０．３０％以下、
　Ａｌ：０．００８～０．３００％、
　Ｏ：０．００３０％以下、
　Ｎ：０．００２０～０．０３００％を含有し、
　さらにＴｉ：０．０２０～０．２００％およびＮｂ：０．０２～０．２０％のうち１種または２種を含有し、
　残部Ｆｅおよび不可避不純物からなる機械構造用鋼からなる鋼材であり、
　さらに、この鋼材のマルテンサイト変態開始温度（Ｍｓ点）が４６０℃以下であり、
　この鋼材についてのジョミニー式一端焼入法により測定される鋼材の焼入端からの距離１．５ｍｍにおける硬さのＪ１．５および距離９ｍｍにおける硬さのＪ９を用いて上記の式（１）により算出の（Ｊ９／Ｊ１．５）の値が０．７０～０．８５の範囲にあり、
　さらに、距離１．５ｍｍにおける硬さのＪ１．５および距離１１ｍｍにおける硬さのＪ１１を用いて、上記の式（２）により算出の（Ｊ１１／Ｊ１．５）の値が０．６７～０．７８の範囲にある、
　熱処理変形の小さい機械構造用鋼材が提供される。 According to another aspect of the present invention, there is provided a steel material for machine structural use having a small heat treatment deformation, the steel material being in mass%,
C: 0.20 to 0.30%
Si: 0.10 to 1.50%,
Mn: 0.10 to 1.20%,
P: 0.030% or less,
S: 0.030% or less,
Cr: 1.30-2.50%,
Cu: 0.30% or less,
Al: 0.008 to 0.300%,
O: 0.0030% or less,
N: 0.0020 to 0.0300% is contained,
Further, Ti contains 0.020 to 0.200% and Nb: 0.02 to 0.20% of one or two,
It is a steel material made of mechanical structural steel consisting of the balance Fe and inevitable impurities,
Furthermore, the martensitic transformation start temperature (Ms point) of this steel material is 460 ° C. or less,
Using the above formula (1), J1.5 of the hardness at a distance of 1.5 mm from the quenching end of the steel material and J9 of the hardness at a distance of 9 mm measured by the Jominy one-end quenching method for this steel material. The calculated (J9 / J1.5) value is in the range of 0.70 to 0.85,
Furthermore, the value of (J11 / J1.5) calculated by the above equation (2) using the hardness J1.5 at a distance of 1.5 mm and the hardness J11 at a distance of 11 mm is 0.67-0. In the range of 78,
A machine structural steel material with small heat treatment deformation is provided.
　本発明の他の一態様によれば、熱処理変形の小さい機械構造用鋼材であって、該鋼材が、質量％で、
　Ｃ：０．２０～０．３０％、
　Ｓｉ：０．１０～１．５０％、
　Ｍｎ：０．１０～１．２０％、
　Ｐ：０．０３０％以下、
　Ｓ：０．０３０％以下、
　Ｃｒ：１．３０～２．５０％、
　Ｃｕ：０．３０％以下、
　Ａｌ：０．００８～０．３００％、
　Ｏ：０．００３０％以下、
　Ｎ：０．００２０～０．０３００％を含有し、
　さらにＮｉ：０．２０～３．００％およびＭｏ：０．０５～０．５０％のうち１種または２種を含有し、
　さらにＴｉ：０．０２０～０．２００％およびＮｂ：０．０２～０．２０％のうち１種または２種を含有し、
　残部Ｆｅおよび不可避不純物からなる機械構造用鋼からなる鋼材であり、
　さらに、この鋼材のマルテンサイト変態開始温度（Ｍｓ点）が４６０℃以下であり、
　この鋼材についてのジョミニー式一端焼入法により測定される鋼材の焼入端からの距離１．５ｍｍにおける硬さのＪ１．５および距離９ｍｍにおける硬さのＪ９を用いて上記の式（１）により算出の（Ｊ９／Ｊ１．５）の値が０．７０～０．８５の範囲にあり、
　さらに、距離１．５ｍｍにおける硬さのＪ１．５および距離１１ｍｍにおける硬さのＪ１１を用いて、上記の式（２）により算出の（Ｊ１１／Ｊ１．５）の値が０．６７～０．７８の範囲にある、
　熱処理変形の小さい機械構造用鋼材が提供される。 According to another aspect of the present invention, there is provided a steel material for machine structural use having a small heat treatment deformation, the steel material being in mass%,
C: 0.20 to 0.30%
Si: 0.10 to 1.50%,
Mn: 0.10 to 1.20%,
P: 0.030% or less,
S: 0.030% or less,
Cr: 1.30-2.50%,
Cu: 0.30% or less,
Al: 0.008 to 0.300%,
O: 0.0030% or less,
N: 0.0020 to 0.0300% is contained,
Furthermore, it contains one or two of Ni: 0.20 to 3.00% and Mo: 0.05 to 0.50%,
Further, Ti contains 0.020 to 0.200% and Nb: 0.02 to 0.20% of one or two,
It is a steel material made of mechanical structural steel consisting of the balance Fe and inevitable impurities,
Furthermore, the martensitic transformation start temperature (Ms point) of this steel material is 460 ° C. or less,
Using the above formula (1), J1.5 of the hardness at a distance of 1.5 mm from the quenching end of the steel and J9 of the hardness at a distance of 9 mm measured by the Jominy one-end quenching method for this steel. The calculated (J9 / J1.5) value is in the range of 0.70 to 0.85,
Further, the value of (J11 / J1.5) calculated by the above equation (2) using J1.5 of the hardness at a distance of 1.5 mm and J11 of the hardness at a distance of 11 mm is 0.67-0. In the range of 78,
A machine structural steel material with small heat treatment deformation is provided.
　本発明の他の一態様によれば、熱処理変形の小さい機械構造用鋼材であって、該鋼材が、質量％で、
　Ｃ：０．２０～０．３０％、
　Ｓｉ：０．１０～１．５０％、
　Ｍｎ：０．１０～１．２０％、
　Ｐ：０．０３０％以下、
　Ｓ：０．０３０％以下、
　Ｃｒ：１．３０～２．５０％、
　Ｃｕ：０．３０％以下、
　Ａｌ：０．００８～０．３００％、
　Ｏ：０．００３０％以下、
　Ｎ：０．００２０～０．０３００％
　Ｎｉ：０～３．００％、
　Ｍｏ：０～０．５０％
　Ｔｉ：０～０．２００％、
　Ｎｂ：０～０．２０％
を含み、残部Ｆｅおよび不可避不純物からなり、
　該鋼材が４６０℃以下のマルテンサイト変態開始温度（Ｍｓ点）を有し、
　ジョミニー式一端焼入法により測定された際に、該鋼材の焼入端からの距離１．５ｍｍにおける硬さＪ１．５に対する、該鋼材の焼入端からの距離９ｍｍにおける硬さＪ９の比（Ｊ９／Ｊ１．５）が０．７０～０．８５の範囲にあり、かつ、該鋼材の焼入端からの距離１．５ｍｍにおける硬さＪ１．５に対する、該鋼材の焼入端からの距離１１ｍｍにおける硬さＪ１１の比（Ｊ１１／Ｊ１．５）が０．６７～０．７８の範囲にある、機械構造用鋼材が提供される。 According to another aspect of the present invention, there is provided a steel material for machine structural use having a small heat treatment deformation, the steel material being in mass%,
C: 0.20 to 0.30%
Si: 0.10 to 1.50%,
Mn: 0.10 to 1.20%,
P: 0.030% or less,
S: 0.030% or less,
Cr: 1.30-2.50%,
Cu: 0.30% or less,
Al: 0.008 to 0.300%,
O: 0.0030% or less,
N: 0.0020 to 0.0300%
Ni: 0 to 3.00%,
Mo: 0 to 0.50%
Ti: 0 to 0.200%,
Nb: 0 to 0.20%
Comprising the balance Fe and inevitable impurities,
The steel material has a martensitic transformation start temperature (Ms point) of 460 ° C. or less,
The ratio of the hardness J9 at a distance of 9 mm from the quenching end of the steel material to the hardness J1.5 at a distance of 1.5 mm from the quenching end of the steel material when measured by the Jomini type one-end quenching method ( J9 / J1.5) is in the range of 0.70 to 0.85, and the distance from the quenching end of the steel to the hardness J1.5 at a distance of 1.5 mm from the quenching end of the steel A steel material for machine structure having a ratio of hardness J11 at 11 mm (J11 / J1.5) in the range of 0.67 to 0.78 is provided.
　本発明の好ましい一態様によれば、上記鋼材はＮｉ、Ｍｏ、Ｔｉ及びＮｂを実質的に含まないか又は不可避不純物のレベルで含む。 According to a preferred aspect of the present invention, the steel material does not substantially contain Ni, Mo, Ti and Nb or contains an inevitable impurity level.
　本発明の好ましい一態様によれば、上記鋼材は、質量％で、Ｎｉ：０．２０～３．００％、およびＭｏ：０．０５～０．５０％のうち１種または２種を含む。 According to a preferred aspect of the present invention, the steel material includes one or two of Ni: 0.20 to 3.00% and Mo: 0.05 to 0.50% in mass%.
　本発明の好ましい一態様によれば、上記鋼材は、質量％で、Ｔｉ：０．０２０～０．２００％、およびＮｂ：０．０２～０．２０％のうち１種または２種を含む。 According to a preferred aspect of the present invention, the steel material includes one or two of Ti: 0.020 to 0.200% and Nb: 0.02 to 0.20% by mass%.
　本発明の好ましい一態様によれば、上記鋼材は、質量％で、Ｎｉ：０．２０～３．００％、およびＭｏ：０．０５～０．５０％のうち１種または２種と、Ｔｉ：０．０２０～０．２００％、およびＮｂ：０．０２～０．２０％のうち１種または２種とを含む。 According to a preferred aspect of the present invention, the steel material is, by mass%, one or two of Ni: 0.20 to 3.00% and Mo: 0.05 to 0.50%, and Ti. : 0.020 to 0.200%, and Nb: 0.02 to 0.20%.
　以下に本発明を具体的に説明する。なお、各成分の「％」は質量％を示す。 The present invention will be specifically described below. In addition, "%" of each component shows the mass%.
　本発明による熱処理変形の小さい機械構造用鋼材は、質量％で、Ｃ：０．２０～０．３０％、Ｓｉ：０．１０～１．５０％、Ｍｎ：０．１０～１．２０％、Ｐ：０．０３０％以下、Ｓ：０．０３０％以下、Ｃｒ：１．３０～２．５０％、Ｃｕ：０．３０％以下、Ａｌ：０．００８～０．３００％、Ｏ：０．００３０％以下、Ｎ：０．００２０～０．０３００％、　Ｎｉ：０～３．００％、Ｍｏ：０～０．５０％、Ｔｉ：０～０．２００％、Ｎｂ：０～０．２０％を含み（comprising）、残部Ｆｅおよび不可避不純物からなるものであり、好ましくはこれらの元素および不可避的不純物から実質的になり（consisting essentially of）、より好ましくはこれらの元素および不可避的不純物のみからなる（consisting of）。 The steel material for mechanical structure with small heat treatment deformation according to the present invention is, in mass%, C: 0.20 to 0.30%, Si: 0.10 to 1.50%, Mn: 0.10 to 1.20%, P: 0.030% or less, S: 0.030% or less, Cr: 1.30 to 2.50%, Cu: 0.30% or less, Al: 0.008 to 0.300%, O: 0.00. 0030% or less, N: 0.0020 to 0.0300%, Ni: 0 to 3.00%, Mo: 0 to 0.50%, Ti: 0 to 0.200%, Nb: 0 to 0.20% Comprising the balance Fe and inevitable impurities, preferably consisting essentially of these elements and inevitable impurities, more preferably consisting only of these elements and inevitable impurities (Consisting of).
　Ｃ：０．２０～０．３０％
　Ｃは、機械構造用部品として鋼材の焼入焼戻し後の強度もしくは浸炭焼入焼戻し後の芯部強度を確保するために必要な元素であり、熱処理変形を小さくするために所定の範囲に調整する必要がある。Ｃの含有量が０．２０％未満では強度を確保できず、０．３０％を超えると熱処理による変形が大きくなり過ぎる。そこでＣの含有量は０．２０～０．３０％とし、望ましくは０．２２～０．２７％とする。 C: 0.20 to 0.30%
C is an element necessary for securing the strength after quenching and tempering of steel or the strength of the core after carburizing, quenching and tempering as mechanical structural parts, and is adjusted to a predetermined range in order to reduce heat treatment deformation. There is a need. If the C content is less than 0.20%, the strength cannot be ensured, and if it exceeds 0.30%, deformation due to heat treatment becomes too large. Therefore, the C content is set to 0.20 to 0.30%, preferably 0.22 to 0.27%.
　Ｓｉ：０．１０～１．５０％
　Ｓｉは、脱酸に必要な元素であるとともに、鋼に必要な強度、焼入性を付与するために有効な元素である。しかし、Ｓｉの含有量が０．１０％未満ではその効果が得られず、１．５０％を超えると機械加工性を低下させる。そこでＳｉの含有量は０．１０～１．５０％とし、望ましくは０．２０～１．００％とする。 Si: 0.10 to 1.50%
Si is an element necessary for deoxidation and is an effective element for imparting necessary strength and hardenability to steel. However, if the Si content is less than 0.10%, the effect cannot be obtained, and if it exceeds 1.50%, the machinability is lowered. Therefore, the Si content is 0.10 to 1.50%, preferably 0.20 to 1.00%.
　Ｍｎ：０．１０～１．２０％
　Ｍｎは、焼入性を確保するために必要な元素である。しかし、Ｍｎの含有量が０．１０％未満では焼入性への効果は十分に得られず、１．２０％を超えると機械加工性を低下させる。そこでＭｎの含有量は０．１０～１．２０％とし、望ましくは０．２０～０．８０％、より望ましくは０．２０～０．５５％とする。 Mn: 0.10 to 1.20%
Mn is an element necessary for ensuring hardenability. However, if the Mn content is less than 0.10%, sufficient effect on hardenability cannot be obtained, and if it exceeds 1.20%, the machinability is lowered. Therefore, the Mn content is 0.10 to 1.20%, preferably 0.20 to 0.80%, and more preferably 0.20 to 0.55%.
　Ｐ：０．０３０％以下
　Ｐは、スクラップから含有される不可避な元素であるが、粒界に偏析して衝撃強度や曲げ強度などの特性を低下させる。そこでＰの含有量は０．０３０％以下（０％を含む）とし、典型的には０を超えて０．０３０％以下とする。 P: 0.030% or less P is an unavoidable element contained in scrap, but segregates at the grain boundary and lowers properties such as impact strength and bending strength. Therefore, the P content is 0.030% or less (including 0%), and typically exceeds 0 and is 0.030% or less.
　Ｓ：０．０３０％以下
　Ｓは、被削性を向上させる元素であるが、非金属介在物であるＭｎＳを生成して横方向の靱性および疲労強度を低下する。そこでＳの含有量は０．０３０％以下（０％を含む）とし、典型的には０を超えて０．０３０％以下とする。 S: 0.030% or less S is an element that improves machinability, but generates MnS that is a non-metallic inclusion and lowers the toughness and fatigue strength in the transverse direction. Therefore, the S content is 0.030% or less (including 0%), and typically exceeds 0 and is 0.030% or less.
　Ｃｒ：１．３０～２．５０％
　Ｃｒは、焼入性を確保するために必要な元素である。しかし、Ｃｒの含有量が１．３０％未満では焼入性への効果は十分に得られず、２．５０％を超えると浸炭を阻害し、また機械加工性も低下する。そこでＣｒの含有量は１．３０～２．５０％とし、望ましくは１．５０～２．２５％とする。 Cr: 1.30-2.50%
Cr is an element necessary for ensuring hardenability. However, if the Cr content is less than 1.30%, a sufficient effect on hardenability cannot be obtained. Therefore, the Cr content is set to 1.30 to 2.50%, preferably 1.50 to 2.25%.
　Ｎｉ：０．２０～３．００％
　Ｎｉは、焼入性および靱性を向上させる任意元素であり、その効果を得るためには０．２０％以上の添加が好ましい。しかし、Ｎｉの含有量が３．００％を超えると加工性が著しく低下し、かつ、コストアップとなるので、３．００％以下とする。そこでＮｉの含有量は０．２０～３．００％とする。 Ni: 0.20 to 3.00%
Ni is an optional element that improves hardenability and toughness, and in order to obtain the effect, addition of 0.20% or more is preferable. However, if the Ni content exceeds 3.00%, the workability is remarkably lowered and the cost is increased, so the content is made 3.00% or less. Therefore, the Ni content is set to 0.20 to 3.00%.
　Ｍｏ：０．０５～０．５０％
　Ｍｏは、焼入性および靱性を向上させる任意元素であり、その効果を得るには０．０５％以上の添加が好ましい。しかし、Ｍｏの含有量が０．５０％を超えると加工性が低下する。そこで、Ｍｏの含有量は０．０５～０．５０％とする。 Mo: 0.05 to 0.50%
Mo is an optional element that improves hardenability and toughness, and 0.05% or more is preferable for obtaining the effect. However, if the Mo content exceeds 0.50%, the workability decreases. Therefore, the Mo content is set to 0.05 to 0.50%.
　Ｃｕ：０．３０％以下
　Ｃｕは、スクラップから含有される不可避な元素であるが、時効性を有し、強度を上昇させる効果がある。しかし、Ｃｕの含有量は０．３０％を超えると熱間加工性を低下させる。そこで、Ｃｕの含有量は０．３０％以下（０％を含む）とし、典型的には０を超えて０．３０％以下とする。 Cu: 0.30% or less Cu is an inevitable element contained from scrap, but has aging properties and an effect of increasing strength. However, when the Cu content exceeds 0.30%, the hot workability is lowered. Therefore, the Cu content is set to 0.30% or less (including 0%), and typically exceeds 0 and is set to 0.30% or less.
　Ａｌ：０．００８～０．３００％
　Ａｌは、脱酸材として使用される元素であり、また後述のようにＮと結合してＡｌＮとして析出して結晶粒粗大化抑制効果をもたらす。この効果を得るため、Ａｌを０．００８％以上添加する必要がある。一方、Ａｌを０．３００％を超えて添加すると大型のアルミナ系介在物を形成し、疲労特性および加工性が低下する。そこで、Ａｌの含有量は０．００８～０．３００％とし、望ましくは０．０１４～０．２００％とする。 Al: 0.008 to 0.300%
Al is an element used as a deoxidizing material, and also binds to N and precipitates as AlN as will be described later, thereby bringing about an effect of suppressing grain coarsening. In order to obtain this effect, 0.008% or more of Al needs to be added. On the other hand, if Al is added in excess of 0.300%, large alumina inclusions are formed, and fatigue characteristics and workability are deteriorated. Therefore, the Al content is set to 0.008 to 0.300%, preferably 0.014 to 0.200%.
　Ｏ：０．００３０％以下
　Ｏは、鋼中に不可避的に含有される元素である。しかし、Ｏが０．００３０％を超えて含有されると酸化物の増加による加工性や疲労強度の低下を招く。そこでＯの含有量は０．００３０％以下（０％を含む）とし、望ましくは０．００２０％以下（０％を含む）とする。また、典型的には０を超えて０．００３０％以下、望ましくは０を超えて０．００２０％以下とする。 O: 0.0030% or less O is an element inevitably contained in steel. However, if O exceeds 0.0030%, workability and fatigue strength are reduced due to an increase in oxide. Therefore, the content of O is set to 0.0030% or less (including 0%), preferably 0.0020% or less (including 0%). Also, typically, it exceeds 0 and is 0.0030% or less, and desirably exceeds 0 and is 0.0020% or less.
　Ｎ：０．００２０～０．０３００％
　Ｎは、鋼中でＡｌＮやＮｂ窒化物として微細析出し、結晶粒粗大化を防止する効果をもたらす元素であり、その効果を得るためにはＮｉを０．００２０％以上添加する必要がある。しかし、Ｎｉの含有量が０．０３００％を超えると窒化物が増加し、疲労強度や加工性が低下する。そこで、Ｎの含有量は０．００２０～０．０３００％とし、望ましくは０．００２０～０．０２００％とする。ただし、特にＴｉを０．０２０％以上含有する鋼においては、ＴｉＮの過剰生成による疲労強度の低下を避けるため、Ｎの含有量は０．００２０～０．０１００％とする。 N: 0.0020 to 0.0300%
N is an element that finely precipitates as AlN or Nb nitride in the steel and has an effect of preventing the coarsening of crystal grains. In order to obtain the effect, it is necessary to add 0.0020% or more of Ni. However, if the Ni content exceeds 0.0300%, nitrides increase and fatigue strength and workability deteriorate. Therefore, the N content is set to 0.0020 to 0.0300%, preferably 0.0020 to 0.0200%. However, particularly in steel containing 0.020% or more of Ti, the N content is set to 0.0020 to 0.0100% in order to avoid a decrease in fatigue strength due to excessive TiN formation.
　Ｔｉ：０．０２０～０．２００％
　Ｔｉは、鋼中のＣと結び付いて炭化物を微細に形成し、結晶粒粗大化を防止する効果をもたらす任意元素であるが、その効果を得るためには、Ｔｉを０．０２０％以上を添加することが好ましい。一方、Ｔｉの含有量が０．２００％を超えると機械加工性を損なう。そこで、Ｔｉの含有量は０．０２０～０．２００％とする。 Ti: 0.020 to 0.200%
Ti is an optional element that combines with C in the steel to form carbides finely and has the effect of preventing grain coarsening. To obtain this effect, 0.020% or more of Ti is added. It is preferable to do. On the other hand, if the Ti content exceeds 0.200%, the machinability is impaired. Therefore, the Ti content is set to 0.020 to 0.200%.
　Ｎｂ：０．０２～０．２０％
　Ｎｂは、炭化物あるいは窒化物を形成し、結晶粒粗大化防止効果をもたらす任意元素である。特に鋼中に微細に分散したナノオーダーサイズのＮｂＣまたはＮｂ（Ｃ，Ｎ）が結晶粒の成長を抑制する。Ｎｂの含有量が０．０２％未満では、その効果は得られず、０．２０％を超えると析出物の量が過剰となり加工性が低下する。そこで、Ｎｂの含有量は０．０２～０．２０％、望ましくは０．０２～０．１２％とする。 Nb: 0.02 to 0.20%
Nb is an arbitrary element that forms carbides or nitrides and has an effect of preventing grain coarsening. In particular, nano-order sized NbC or Nb (C, N) finely dispersed in steel suppresses the growth of crystal grains. If the Nb content is less than 0.02%, the effect cannot be obtained. If the Nb content exceeds 0.20%, the amount of precipitates becomes excessive and workability deteriorates. Therefore, the Nb content is 0.02 to 0.20%, preferably 0.02 to 0.12%.
　さらに、上記の成分の限定理由以外のＭｓ点およびジョミニー式一端焼入法により測定される焼入性の限定理由について説明する。 Furthermore, the reasons for limiting the Ms point and the hardenability measured by the Jominy one-side quenching method other than the reasons for limiting the above components will be described.
　Ｍｓ点：４６０℃以下
　本発明による鋼材においては、鋼材の熱処理変形を小さくするために、マルテンサイト変態開始温度（Ｍｓ点）を４６０℃以下に規制する必要がある。Ｍｓ点を４６０℃以下に規制することで熱処理変形を小さくできる理由は、焼入れした際に、部品の冷却がたとい不均一であっても、冷媒の冷却性能が高い温度域で、マルテンサイト変態が起こることを回避でき、その結果、マルテンサイト変態の時期が部品の部位によって大きくずれることが抑制できるからである。そこでＭｓ点を４６０℃以下に規制するが、望ましくはＭｓ点は４５０℃以下に規制する。なお、この場合の熱処理変形とは、軸状部品の曲がりやギヤの歯の倒れやねじれのことである。 Ms point: 460 ° C. or less In the steel material according to the present invention, it is necessary to regulate the martensite transformation start temperature (Ms point) to 460 ° C. or less in order to reduce the heat treatment deformation of the steel material. The reason why heat treatment deformation can be reduced by restricting the Ms point to 460 ° C. or less is that, even when the parts are not cooled when quenched, the martensitic transformation occurs in the temperature range where the cooling performance of the refrigerant is high. This is because it can be avoided, and as a result, it can be suppressed that the martensitic transformation time largely deviates depending on the parts. Therefore, the Ms point is restricted to 460 ° C. or lower, but preferably the Ms point is restricted to 450 ° C. or lower. In this case, the heat treatment deformation means bending of the shaft-shaped part, falling of the gear teeth, or twisting.
　（Ｊ９／Ｊ１．５）の値：０．７０～０．８５
　（Ｊ１１／Ｊ１．５）の値：０．６７～０．７８
　ジョミニー式一端焼入法により測定した際の、鋼材の焼入端からの距離１．５ｍｍにおける硬さＪ１．５に対する、該鋼材の焼入端からの距離９ｍｍにおける硬さＪ９の比（Ｊ９／Ｊ１．５）が０．７０～０．８５の範囲内にあり、鋼材の焼入端からの距離１．５ｍｍにおける硬さＪ１．５に対する、該鋼材の焼入端からの距離１１ｍｍにおける硬さＪ１１の比（Ｊ１１／Ｊ１．５）が０．６７～０．７８の範囲内にあると、鋼材の熱処理変形を小さく抑えることができる。ここで言う熱処理変形とは、焼入れ後の軸状部品の曲がりやギヤの歯の倒れやねじれ、また、焼入れ前後における部品の寸法（長さ、径、厚み等）の変化のことである。なお、ジョミニー焼入性を適切な範囲に制御することで熱処理変形が抑制されるメカニズムについては、未だ十分に解明できていないが、ジョミニー焼入性が低すぎても、高すぎても熱処理変形が増大することは本発明者らにより実験的に確かめられている。理論に拘束されるものではないが、この範囲のジョミニー焼入性を有する鋼においては、焼入れの冷却過程においてマルテンサイト変態に先立ってベイナイト変態が適度に起こり、鋼材強度が高められ、ある程度変形しにくくなった状態からマルテンサイト変態が開始するために熱処理変形が抑えられるものと考えられる。一方、焼入性が低すぎる場合には、ベイナイト変態が過剰に起こるため、ベイナイト変態自体の影響によって熱処理変形が増大し、また、焼入れ性が高すぎる場合には、熱処理変形を緩和するベイナイト組織が少ないためにやはり熱処理変形が増大すると考えられる。 Value of (J9 / J1.5): 0.70 to 0.85
Value of (J11 / J1.5): 0.67 to 0.78
The ratio of the hardness J9 at a distance of 9 mm from the quenching end of the steel material to the hardness J1.5 at a distance of 1.5 mm from the quenching end of the steel material (J9 / J1.5) is in the range of 0.70 to 0.85, and the hardness at a distance of 11 mm from the quenching end of the steel relative to the hardness J1.5 at a distance of 1.5 mm from the quenching end of the steel When the ratio of J11 (J11 / J1.5) is in the range of 0.67 to 0.78, the heat treatment deformation of the steel material can be kept small. The heat treatment deformation referred to here is the bending of the shaft-shaped part, the gear teeth falling or twisting after quenching, and the change in the dimension (length, diameter, thickness, etc.) of the part before and after quenching. Although the mechanism by which heat treatment deformation is suppressed by controlling the Jominy hardenability within an appropriate range has not yet been fully elucidated, heat treatment deformation can be achieved even if Jominy hardenability is too low or too high. It has been experimentally confirmed by the present inventors that this increases. Without being bound by theory, in steels with Jominy hardenability in this range, bainite transformation occurs moderately prior to martensitic transformation in the quenching cooling process, increasing the strength of the steel material and deforming to some extent. It is considered that the deformation due to heat treatment is suppressed because the martensitic transformation starts from the difficult state. On the other hand, if the hardenability is too low, the bainite transformation occurs excessively, so that the heat treatment deformation increases due to the influence of the bainite transformation itself, and if the hardenability is too high, the bainite structure relaxes the heat treatment deformation. It is considered that the deformation due to heat treatment is also increased due to the small amount.
　上述したような鋼成分の限定、Ｍｓ点の限定およびジョミニー式一端焼入法により測定される焼入性の限定により、鋼材を部品に加工した後、部品を硬化させるための焼入れや浸炭焼入れを行った場合の熱処理変形を小さくすることができる。この結果、本発明は、部品の歩留の向上、部品の矯正工程の簡略化や廃止、あるいは騒音および振動対策のためのギヤの歯面研削の省略が期待されるといった有益な効果を奏することができる。 After the steel material is processed into a part by the limitation of steel components, the Ms point, and the hardenability limit measured by the Jominy one-side quenching method as described above, quenching and carburizing and quenching are performed to harden the part. The heat treatment deformation when performed can be reduced. As a result, the present invention has beneficial effects such as improvement of component yield, simplification and abolition of component correction processes, and omission of gear tooth grinding for noise and vibration countermeasures. Can do.
　本発明に係る鋼材を以下の例に基づいて具体的に説明する。 The steel material according to the present invention will be specifically described based on the following examples.
　自動車や産業機械などに使用されるギヤやシャフトなどの動力伝達用の部品として用いられる機械構造用鋼を得るために、表１に示す発明例のＮｏ．１～２３の成分組成と、残部Ｆｅおよび不可避不純物からなる鋼を真空誘導溶解炉にて溶製し、１００ｋｇの鋼塊を得た。 In order to obtain mechanical structural steels used as power transmission parts such as gears and shafts used in automobiles and industrial machines, the No. of the invention examples shown in Table 1 were obtained. Steel consisting of 1 to 23, the remainder Fe and unavoidable impurities was melted in a vacuum induction melting furnace to obtain a 100 kg steel ingot.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　上記の本発明例と同様に、自動車や産業機械などに使用されるギヤやシャフトなどの動力伝達用の部品として用いられる機械構造用鋼として、表２に示す比較例のＮｏ．１～１６の成分組成と、残部Ｆｅおよび不可避不純物からなる鋼を真空誘導溶解炉にて溶製し、１００ｋｇの鋼塊を得た。 As in the above-described examples of the present invention, as a structural steel used as a power transmission component such as a gear or a shaft used in automobiles or industrial machines, the comparative example No. 2 shown in Table 2 was used. Steel consisting of 1 to 16 component compositions, the balance Fe and unavoidable impurities was melted in a vacuum induction melting furnace to obtain a 100 kg steel ingot.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　先ず、これらの本発明例および比較例の上記で溶製された鋼塊を、１２５０℃で５時間加熱した後、直径３２ｍｍの棒鋼に鍛伸した。次に、９００℃で１．５時間加熱保持した後に空冷する焼ならしを行った。続いて、直径３２ｍｍの棒鋼から直径２０ｍｍ、長さ８０ｍｍの試験片を作製し、その試験片の側面に、深さ５ｍｍ、幅８ｍｍ、長さ８０ｍｍの溝加工を施した。この溝加工によって焼き入れた際に、試験片内の部位によって冷却速度に大きく差がつくようにした。また、溝加工後に試験片の長さを測定した。さらに試験片端部から２ｍｍ、２０ｍｍ、および試験片長さの中央である４０ｍｍの各位置における半径および溝幅を測定した。続いて、これらの試験片を９３０℃で浸炭した後、炉内で８５０℃まで降温し、さらに１時間保持してから６０℃の焼入油中へ焼入れした。焼入れ後、十分に冷えた試験片について、試験片の曲り、長さ、および試験片端部から２ｍｍ、２０ｍｍ、および試験片長さの中央である４０ｍｍの各位置における半径および溝幅を測定した。 First, these ingots of the present invention and comparative examples were heated at 1250 ° C. for 5 hours and then forged into a steel bar having a diameter of 32 mm. Next, normalizing was performed by heating and holding at 900 ° C. for 1.5 hours and then air cooling. Subsequently, a test piece having a diameter of 20 mm and a length of 80 mm was produced from a steel bar having a diameter of 32 mm, and a groove having a depth of 5 mm, a width of 8 mm, and a length of 80 mm was applied to the side surface of the test piece. When quenching was performed by this groove processing, the cooling rate was varied greatly depending on the portion in the test piece. Moreover, the length of the test piece was measured after the groove processing. Further, the radius and groove width were measured at each position of 2 mm, 20 mm from the end of the test piece, and 40 mm which is the center of the test piece length. Then, after carburizing these test pieces at 930 ° C., the temperature was lowered to 850 ° C. in the furnace, and further maintained for 1 hour, and then quenched into a quenching oil at 60 ° C. After quenching, the specimens that were sufficiently cooled were measured for the bend and length of the specimen and the radius and groove width at each position of 2 mm, 20 mm from the specimen edge, and 40 mm, which is the center of the specimen length.
　なお、熱処理後の曲りについては、試験片の両端をＶブロックで保持し、試験片を一周回転させたときの試験片の中央部の円周上の最大変位と最小変位をダイヤルゲージで測定し、最大変位と最小変位の差を２で割ることにより求めた。この測定の際、試験片の円周上に存在する溝の底の部分の変位は無視するものとした。また、熱処理変形の指標として、熱処理前後の試験片の長さの差を求め、その絶対値を評価した。さらに、試験片端部から２ｍｍ、２０ｍｍ、および試験片長さの中央である４０ｍｍの合計３箇所の各位置における熱処理前後の半径、および溝幅の寸法測定結果から、各箇所の熱処理前後の半径、および溝幅の寸法変化量を求めたのち、その３箇所における寸法変化量のうちの最大値から最小値を差し引いた値を、それぞれ半径変化量、および溝幅変化量と定義して、これを熱処理変形の指標として評価した。 For bending after heat treatment, hold both ends of the test piece with V block, and measure the maximum and minimum displacement on the circumference of the center of the test piece with a dial gauge when the test piece is rotated once. The difference between the maximum displacement and the minimum displacement was obtained by dividing by 2. In this measurement, the displacement of the bottom portion of the groove existing on the circumference of the test piece was ignored. In addition, as an index of heat treatment deformation, a difference in length of the test piece before and after the heat treatment was obtained, and the absolute value thereof was evaluated. Furthermore, the radius before and after the heat treatment at each position of the total three locations of 2 mm, 20 mm from the end of the test piece, and 40 mm which is the center of the length of the test piece, and the groove width dimension measurement result, After obtaining the dimensional change amount of the groove width, the values obtained by subtracting the minimum value from the maximum value among the dimensional change amounts at the three locations are defined as the radius change amount and the groove width change amount, respectively. It was evaluated as an index of deformation.
　また、上記の焼ならし後の直径３２ｍｍの棒鋼から、直径３ｍｍで長さ１０ｍｍの試験片を割り出し、鋼材のマルテンサイト変態開始温度であるＭｓ点を、全自動変態記録測定装置を用いて測定した。本実施の形態におけるＭｓ点は、部品の冷却過程を想定した条件下で実測測定されるものであり、本実施の形態においては、上記した直径２０ｍｍの溝付き試験片の油温６０℃の場合の油焼入れを想定して、焼入れ時の冷却速度を３０℃／ｓとして測定した。鋼材のジョミニー式一端焼入法による焼入性の測定については、上記の鍛伸した直径３２ｍｍの棒鋼から試験片を作製し、ＪＩＳ　Ｇ　０５６１に規定される「鋼の焼入性試験方法（一端焼入方法）」に準じた条件の下で試験を行って評価した。 In addition, a test piece having a diameter of 3 mm and a length of 10 mm is determined from the steel bar having a diameter of 32 mm after the above normalization, and the Ms point, which is the martensitic transformation start temperature of the steel material, is measured using a fully automatic transformation recording measuring device. did. The Ms point in the present embodiment is measured and measured under the condition that the cooling process of the component is assumed. In the present embodiment, the above-described grooved test piece having a diameter of 20 mm has an oil temperature of 60 ° C. Assuming oil quenching, the cooling rate during quenching was measured at 30 ° C./s. For the measurement of the hardenability of steel by the Jominy type one-end quenching method, a test piece was prepared from the above-described forged steel bar with a diameter of 32 mm, and “steel hardenability test method (one end) specified in JIS G 0561”. The test was conducted under the conditions according to the quenching method) and evaluated.
　表３に本発明例の鋼について測定されたＭｓ点、ジョミニー式一端焼入法で測定した焼入端からの、距離１．５ｍｍにおける硬さのＪ１．５、距離９ｍｍにおける硬さのＪ９および距離１１ｍｍにおける硬さのＪ１１のそれぞれの値、また、求めた（Ｊ９／Ｊ１．５）の値および（Ｊ１１／Ｊ１．５）の値を示す。さらに、上記の試験片の焼入れ後に評価した曲り（単位ｍｍ）、熱処理前後の試験片の長さの差の絶対値（単位ｍｍ）、および上記の方法により求めた熱処理前後の試験片の半径変化量（単位ｍｍ）および溝幅変化量（単位ｍｍ）を示す。発明例のＮｏ．１～２３からなる鋼材では、表３に示すように、マルテンサイト変態開始温度すなわちＭｓ点が３８８～４４４℃の範囲にあり、この鋼材の（Ｊ９／Ｊ１．５）の下記に示す式（１）の値が０．７２～０．８５の範囲にあり、（Ｊ１１／Ｊ１．５）の下記に示す式（２）の値が０．６７～０．７８の範囲にあり、熱処理後の曲りは０．００５～０．０３０ｍｍであり、熱処理前後の試験片の長さの差の絶対値は０．００３～０．０２３ｍｍであり、熱処理前後の半径変化量は０．００２～０．００８ｍｍであり、熱処理前後の溝幅変化量は０．０１１～０．０２４ｍｍであった。
　ただし、
　（Ｊ９／Ｊ１．５）＝（ジョミニー式一端焼入法により測定される焼入れ端からの距離９ｍｍの硬さ）÷（ジョミニー式一端焼入法により測定される焼入れ端からの距離１．５ｍｍの硬さ）……（１）
　（Ｊ１１／Ｊ１．５）＝（ジョミニー式一端焼入法により測定される焼入れ端からの距離１１ｍｍの硬さ）÷（ジョミニー式一端焼入法により測定される焼入れ端からの距離１．５ｍｍの硬さ）……（２） Table 3 shows the Ms point measured for the steel of the present invention, J1.5 of the hardness at a distance of 1.5 mm, J9 of the hardness at a distance of 9 mm from the quenching end measured by the Jomini type one-end quenching method, and Each value of the hardness J11 at a distance of 11 mm, and the obtained (J9 / J1.5) value and (J11 / J1.5) value are shown. Further, the bending (unit: mm) evaluated after quenching the above test piece, the absolute value of the difference in length of the test piece before and after the heat treatment (unit: mm), and the radius change of the test piece before and after the heat treatment determined by the above method An amount (unit: mm) and a groove width change amount (unit: mm) are shown. Invention Example No. As shown in Table 3, in the steel material consisting of 1 to 23, the martensite transformation start temperature, that is, the Ms point is in the range of 388 to 444 ° C., and (J9 / J1.5) of this steel material is represented by the following formula (1 ) Is in the range of 0.72 to 0.85, the value of formula (2) shown below in (J11 / J1.5) is in the range of 0.67 to 0.78, and the bend after heat treatment Is 0.005 to 0.030 mm, the absolute value of the difference in length of the test piece before and after heat treatment is 0.003 to 0.023 mm, and the amount of change in radius before and after heat treatment is 0.002 to 0.008 mm. The change in groove width before and after the heat treatment was 0.011 to 0.024 mm.
However,
(J9 / J1.5) = (hardness at a distance of 9 mm from the quenching end measured by the Jomini type one-end quenching method) ÷ (1.5 mm from the quenching end measured by the Jominy type one-end quenching method) (Hardness) …… (1)
(J11 / J1.5) = (hardness at a distance of 11 mm from the quenching end measured by the Jomini type one-end quenching method) ÷ (a distance of 1.5 mm from the quenching end measured by the Jominy type one-end quenching method) (Hardness) …… (2)
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　同様に、表４に比較例の鋼の測定されたＭｓ点、ジョミニー式一端焼入法により測定した焼入端からの距離１．５ｍｍにおける硬さ（ＨＲＣ）のＪ１．５、距離９ｍｍにおける硬さ（ＨＲＣ）のＪ９、および距離１１ｍｍにおける硬さ（ＨＲＣ）のＪ１１であるジョミニー焼入性、また、求めた（Ｊ９／Ｊ１．５）の値および（Ｊ１１／Ｊ１．５）の値を示す。さらに、上記試験片の焼入れ後の曲り（単位ｍｍ）、および、熱処理前後の試験片の長さの差の絶対値（単位ｍｍ）、および上記の方法により求めた熱処理前後の試験片の半径変化量（単位ｍｍ）、および溝幅変化量（単位ｍｍ）を示す。 Similarly, Table 4 shows the measured Ms point of the steel of the comparative example, J1.5 of the hardness (HRC) at a distance of 1.5 mm from the quenching end measured by the Jomini type one-end quenching method, and the hardness at a distance of 9 mm. Jominy hardenability which is J9 of thickness (HRC) and J11 of hardness (HRC) at a distance of 11 mm, and the obtained values of (J9 / J1.5) and (J11 / J1.5) are shown. . Further, the bending of the test piece after quenching (unit: mm), the absolute value of the difference in length of the test piece before and after the heat treatment (unit: mm), and the radius change of the test piece before and after the heat treatment determined by the above method The amount (unit: mm) and the groove width change amount (unit: mm) are shown.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　上記の発明例のＮｏ．１～２３では、鋼材のＦｅおよびＮｉ、Ｍｏ以外の不可避不純物を除いた組成範囲を表１に示すものとし、Ｍｓ点を４６０℃以下の３８８～４４４℃とし、ジョミニー式一端焼入法により測定される焼入性を適切に制御して、式（１）から計算される（Ｊ９／Ｊ１．５）の値を０．７２～０．８５の範囲に、式（２）から計算される（Ｊ１１／Ｊ１．５）の値を０．６７～０．７８の範囲とすることによって、熱処理後の試験片の曲りを０．００５～０．０３０ｍｍの小さな範囲に、さらに熱処理前後の試験片の長さの差の絶対値を０．００３～０．０２３ｍｍの小さな範囲に、さらに熱処理前後の半径変化量を０．００２～０．００８ｍｍの小さな範囲に、さらに熱処理前後の溝幅変化量を０．０１１～０．０２４ｍｍの小さな範囲に抑えることができた。 No. in the above invention example. For 1 to 23, the composition range excluding unavoidable impurities other than Fe, Ni, and Mo of steel materials is shown in Table 1, Ms point is set to 388 to 444 ° C. below 460 ° C., and measured by Jomini type one-end quenching method By appropriately controlling the hardenability to be performed, the value of (J9 / J1.5) calculated from the equation (1) is calculated within the range of 0.72 to 0.85 from the equation (2) ( By setting the value of J11 / J1.5) in the range of 0.67 to 0.78, the bending of the test piece after the heat treatment is reduced to a small range of 0.005 to 0.030 mm, and the test piece before and after the heat treatment is further reduced. The absolute value of the difference in length is in a small range of 0.003 to 0.023 mm, the change in radius before and after heat treatment is in a small range of 0.002 to 0.008 mm, and the change in groove width before and after heat treatment is 0. .Small range from 011 to 0.024mm It could be.
　これに対し、上記の比較例のＮｏ．１～１６の、鋼材のＦｅおよびＮｉ、Ｍｏ以外の不可避不純物を除いた組成範囲を表２に示すものでは、Ｎｏ．２、Ｎｏ．１６の２例を除く、残りの１４例は本発明の組成範囲から外れるものであった。これらＮｏ．１～１６の比較例の鋼は、ジョミニー式一端焼入法によって測定した硬さから式（１）、および式（２）により求まる（Ｊ９／Ｊ１．５）の値が０．７０～０．８５の範囲外であり、および（Ｊ１１／Ｊ１．５）の値が０．６７～０．７８の範囲外である。また、これらＮｏ．１～１６の比較例の鋼のうち、９例は測定されたＭｓ点が４６０℃を超えるものである。比較例１～１６は、熱処理後の試験片の曲がりが０．０５０～０．０９０ｍｍであり、いずれも発明例の鋼に比べ大きい。また、これらＮｏ．１～１６の比較例の鋼は、熱処理前後の試験片の長さの差の絶対値、あるいは熱処理前後の半径変化量および溝幅変化量のうち、いずれか一つ以上の値が本発明の鋼に比べて大きい。したがって、比較例のうちで熱処理後の試験片の曲り、熱処理前後の試験片の長さの差の絶対値、および熱処理前後の半径変化量および溝幅変化量の全てが本発明例の鋼と同等のものは１例も無かった。 In contrast, No. in the above comparative example. In Table 2, the composition ranges excluding inevitable impurities other than Fe, Ni, and Mo of steel materials 1 to 16 are shown in Table 2. 2, No. The remaining 14 cases, excluding 16 2 cases, were out of the composition range of the present invention. These No. The steels of Comparative Examples 1 to 16 have a value (J9 / J1.5) of 0.70 to 0. 0 determined by the formula (1) and the formula (2) from the hardness measured by the Jomini type one-end quenching method. It is out of the range of 85, and the value of (J11 / J1.5) is out of the range of 0.67 to 0.78. In addition, these No. Of the 1 to 16 comparative steels, 9 have a measured Ms point above 460 ° C. In Comparative Examples 1 to 16, the bending of the test piece after the heat treatment is 0.050 to 0.090 mm, and all are larger than the steel of the inventive example. In addition, these No. In the steels of Comparative Examples 1 to 16, any one or more of the absolute value of the difference in length of the test pieces before and after the heat treatment, or the radius change amount and the groove width change amount before and after the heat treatment is the value of the present invention. Bigger than steel. Therefore, among the comparative examples, the bending of the test piece after the heat treatment, the absolute value of the difference in length of the test piece before and after the heat treatment, and the radius change amount and the groove width change amount before and after the heat treatment are all the same as the steel of the present invention example. There was no one equivalent.
　Ｍｓ点が本発明の請求の範囲を満足し、（Ｊ９／Ｊ１．５）の値および（Ｊ１１／Ｊ１．５）の値が本発明の請求の範囲を満足する、本発明例のＮｏ．１～２３は、熱処理後の試験片の曲り、熱処理前後の試験片の長さの差の絶対値、および熱処理前後の半径変化量および溝幅変化量が比較例に比して略小さく、熱処理変形が抑制されている。なお、本発明例の鋼材は浸炭焼入れ等の部品を硬化させるための焼入れをともなう熱処理を施した後、焼戻しを施してから使用される。 The Ms point satisfies the claims of the present invention, and the values of (J9 / J1.5) and (J11 / J1.5) satisfy the claims of the present invention. In Nos. 1 to 23, the bending of the test piece after the heat treatment, the absolute value of the difference in the length of the test piece before and after the heat treatment, and the radius change amount and the groove width change amount before and after the heat treatment are substantially smaller than those in the comparative example. Deformation is suppressed. The steel material of the present invention is used after being tempered after being subjected to heat treatment with hardening for hardening parts such as carburizing and quenching.
　以上から、本発明における鋼成分の限定およびマルテンサイト変態開始温度であるＭｓ点の限定およびジョミニー式一端焼入法により測定される焼入性の限定により、鋼材を部品に加工した後、浸炭焼入れ等、部品を硬化させるための焼入れをともなう熱処理を行った場合の熱処理変形を小さくすることができる。この結果、本発明による鋼材は、自動車や産業機械などに使用されるギヤやシャフトなどの動力伝達用の部品に適用しうる鋼材である。 From the above, after the steel material was processed into parts by the limitation of the steel components and the Ms point which is the martensitic transformation start temperature and the limitation of the hardenability measured by the Jominy one-side quenching method, carburizing and quenching was performed. For example, the heat treatment deformation when the heat treatment with hardening for hardening the parts is performed can be reduced. As a result, the steel material according to the present invention is a steel material applicable to power transmission parts such as gears and shafts used in automobiles and industrial machines.

Claims (4)

  1. 　質量％で、
    　Ｃ：０．２０～０．３０％、
    　Ｓｉ：０．１０～１．５０％、
    　Ｍｎ：０．１０～１．２０％、
    　Ｐ：０．０３０％以下、
    　Ｓ：０．０３０％以下、
    　Ｃｒ：１．３０～２．５０％、
    　Ｃｕ：０．３０％以下、
    　Ａｌ：０．００８～０．３００％、
    　Ｏ：０．００３０％以下、
    　Ｎ：０．００２０～０．０３００％を含有し、
    　残部Ｆｅおよび不可避不純物からなる機械構造用鋼であり、
    　該鋼からなる鋼材のマルテンサイト変態開始温度（Ｍｓ点）が４６０℃以下であり、
    　該鋼材についてのジョミニー式一端焼入法により測定される鋼材の焼入端からの距離１．５ｍｍにおける硬さのＪ１．５および距離９ｍｍにおける硬さのＪ９を用いて、下記の式（１）によって算出した（Ｊ９／Ｊ１．５）の値が０．７０～０．８５の範囲にあり、
    　さらに距離１．５ｍｍにおける硬さのＪ１．５および距離１１ｍｍにおける硬さのＪ１１を用いて、下記の式（２）によって算出した（Ｊ１１／Ｊ１．５）の値が０．６７～０．７８の範囲にある、
    　熱処理変形の小さい機械構造用鋼材。
    　ただし、
    　（Ｊ９／Ｊ１．５）＝（ジョミニー式一端焼入法により測定される焼入端からの距離９ｍｍの硬さ）÷（ジョミニー式一端焼入法により測定される焼入端からの距離１．５ｍｍの硬さ）……式（１）
    　（Ｊ１１／Ｊ１．５）＝（ジョミニー式一端焼入法により測定される焼入端からの距離１１ｍｍの硬さ）÷（ジョミニー式一端焼入法により測定される焼入端からの距離１．５ｍｍの硬さ）……式（２）     % By mass
    C: 0.20 to 0.30%
    Si: 0.10 to 1.50%,
    Mn: 0.10 to 1.20%,
    P: 0.030% or less,
    S: 0.030% or less,
    Cr: 1.30-2.50%,
    Cu: 0.30% or less,
    Al: 0.008 to 0.300%,
    O: 0.0030% or less,
    N: 0.0020 to 0.0300% is contained,
    It is a steel for machine structure consisting of the balance Fe and inevitable impurities,
    The martensitic transformation start temperature (Ms point) of the steel material made of the steel is 460 ° C. or less,
    The following formula (1) is used by using J1.5 of the hardness at a distance of 1.5 mm from the quenching end of the steel material and J9 of the hardness at a distance of 9 mm measured by the Jominy-type one-end quenching method for the steel material. The value of (J9 / J1.5) calculated by is in the range of 0.70 to 0.85,
    Further, using the hardness J1.5 at a distance of 1.5 mm and the hardness J11 at a distance of 11 mm, the value of (J11 / J1.5) calculated by the following equation (2) is 0.67 to 0.78. In the range of
    Machine structural steel with small heat treatment deformation.
    However,
    (J9 / J1.5) = (hardness at a distance of 9 mm from the quenching end measured by the Jomini type one-end quenching method) ÷ (distance from the quenching end measured by the Jominy type one-end quenching method. (Hardness of 5mm) …… Formula (1)
    (J11 / J1.5) = (hardness of a distance of 11 mm from the quenching end measured by the Jomini-type one-end quenching method) ÷ (distance from the quenching end measured by the Jomini-type one-end quenching method. (Hardness of 5mm) …… Formula (2)
  2. 　質量％で、
    　Ｃ：０．２０～０．３０％、
    　Ｓｉ：０．１０～１．５０％、
    　Ｍｎ：０．１０～１．２０％、
    　Ｐ：０．０３０％以下、
    　Ｓ：０．０３０％以下、
    　Ｃｒ：１．３０～２．５０％、
    　Ｃｕ：０．３０％以下、
    　Ａｌ：０．００８～０．３００％、
    　Ｏ：０．００３０％以下、
    　Ｎ：０．００２０～０．０３００％を含有し、
    　さらにＮｉ：０．２０～３．００％およびＭｏ：０．０５～０．５０％の１種または２種を含有し、
    　残部Ｆｅおよび不可避不純物からなる機械構造用鋼であり、
    　該鋼からなる鋼材のマルテンサイト変態開始温度（Ｍｓ点）が４６０℃以下であり、
    　該鋼材についてのジョミニー式一端焼入法により測定される鋼材の焼入端からの距離１．５ｍｍにおける硬さのＪ１．５および距離９ｍｍにおける硬さのＪ９を用いて、下記の式（１）によって算出した（Ｊ９／Ｊ１．５）の値が０．７０～０．８５の範囲にあり、
    　さらに距離１．５ｍｍにおける硬さのＪ１．５および距離１１ｍｍにおける硬さのＪ１１を用いて、下記の式（２）によって算出した（Ｊ１１／Ｊ１．５）の値が０．６７～０．７８の範囲にある、
    　熱処理変形の小さい機械構造用鋼材。
    　ただし、
    　（Ｊ９／Ｊ１．５）＝（ジョミニー式一端焼入法により測定される焼入端からの距離９ｍｍの硬さ）÷（ジョミニー式一端焼入法により測定される焼入端からの距離１．５ｍｍの硬さ）……（１）
    　（Ｊ１１／Ｊ１．５）＝（ジョミニー式一端焼入法により測定される焼入端からの距離１１ｍｍの硬さ）÷（ジョミニー式一端焼入法により測定される焼入端からの距離１．５ｍｍの硬さ）……（２）     % By mass
    C: 0.20 to 0.30%
    Si: 0.10 to 1.50%,
    Mn: 0.10 to 1.20%,
    P: 0.030% or less,
    S: 0.030% or less,
    Cr: 1.30-2.50%,
    Cu: 0.30% or less,
    Al: 0.008 to 0.300%,
    O: 0.0030% or less,
    N: 0.0020 to 0.0300% is contained,
    Furthermore, it contains one or two of Ni: 0.20 to 3.00% and Mo: 0.05 to 0.50%,
    It is a steel for machine structure consisting of the balance Fe and inevitable impurities,
    The martensitic transformation start temperature (Ms point) of the steel material made of the steel is 460 ° C. or less,
    The following formula (1) is used by using J1.5 of the hardness at a distance of 1.5 mm from the quenching end of the steel material and J9 of the hardness at a distance of 9 mm measured by the Jominy-type one-end quenching method for the steel material. The value of (J9 / J1.5) calculated by is in the range of 0.70 to 0.85,
    Further, using the hardness J1.5 at a distance of 1.5 mm and the hardness J11 at a distance of 11 mm, the value of (J11 / J1.5) calculated by the following equation (2) is 0.67 to 0.78. In the range of
    Machine structural steel with small heat treatment deformation.
    However,
    (J9 / J1.5) = (hardness at a distance of 9 mm from the quenching end measured by the Jomini type one-end quenching method) ÷ (distance from the quenching end measured by the Jominy type one-end quenching method. (Hardness of 5mm) …… (1)
    (J11 / J1.5) = (hardness of a distance of 11 mm from the quenching end measured by the Jomini-type one-end quenching method) ÷ (distance from the quenching end measured by the Jomini-type one-end quenching method. (Hardness of 5mm) …… (2)
  3. 　質量％で、
    　Ｃ：０．２０～０．３０％、
    　Ｓｉ：０．１０～１．５０％、
    　Ｍｎ：０．１０～１．２０％、
    　Ｐ：０．０３０％以下、
    　Ｓ：０．０３０％以下、
    　Ｃｒ：１．３０～２．５０％、
    　Ｃｕ：０．３０％以下、
    　Ａｌ：０．００８～０．３００％、
    　Ｏ：０．００３０％以下、
    　Ｎ：０．００２０～０．０３００％を含有し、
    　さらにＴｉ：０．０２０～０．２００％およびＮｂ：０．０２～０．２０％の１種または２種を含有し、
    　残部Ｆｅおよび不可避不純物からなる機械構造用鋼であり、
    　該鋼からなる鋼材のマルテンサイト変態開始温度（Ｍｓ点）が４６０℃以下であり、
    　該鋼材についてジョミニー式一端焼入法により測定される鋼材の焼入端からの距離１．５ｍｍにおける硬さのＪ１．５および距離９ｍｍにおける硬さのＪ９を用いて、下記の式（１）によって算出した（Ｊ９／Ｊ１．５）の値が０．７０～０．８５の範囲にあり、
    　さらに距離１．５ｍｍにおける硬さのＪ１．５および距離１１ｍｍにおける硬さのＪ１１を用いて、下記の式（２）によって算出した（Ｊ１１／Ｊ１．５）の値が０．６７～０．７８の範囲にある、
    　熱処理変形の小さい機械構造用鋼材。
    　ただし、
    　（Ｊ９／Ｊ１．５）＝（ジョミニー式一端焼入法により測定される焼入れ端からの距離９ｍｍの硬さ）÷（ジョミニー式一端焼入法により測定される焼入れ端からの距離１．５ｍｍの硬さ）……（１）
    　（Ｊ１１／Ｊ１．５）＝（ジョミニー式一端焼入法により測定される焼入れ端からの距離１１ｍｍの硬さ）÷（ジョミニー式一端焼入法により測定される焼入れ端からの距離１．５ｍｍの硬さ）……（２）     % By mass
    C: 0.20 to 0.30%
    Si: 0.10 to 1.50%,
    Mn: 0.10 to 1.20%,
    P: 0.030% or less,
    S: 0.030% or less,
    Cr: 1.30-2.50%,
    Cu: 0.30% or less,
    Al: 0.008 to 0.300%,
    O: 0.0030% or less,
    N: 0.0020 to 0.0300% is contained,
    Furthermore, it contains one or two of Ti: 0.020-0.200% and Nb: 0.02-0.20%,
    It is a steel for machine structure consisting of the balance Fe and inevitable impurities,
    The martensitic transformation start temperature (Ms point) of the steel material made of the steel is 460 ° C. or less,
    With respect to the steel material, J1.5 of the hardness at a distance of 1.5 mm from the quenching end of the steel material measured by the Jominy type one-end quenching method and J9 of the hardness at a distance of 9 mm are used according to the following formula (1). The calculated (J9 / J1.5) value is in the range of 0.70 to 0.85,
    Further, using the hardness J1.5 at a distance of 1.5 mm and the hardness J11 at a distance of 11 mm, the value of (J11 / J1.5) calculated by the following equation (2) is 0.67 to 0.78. In the range of
    Machine structural steel with small heat treatment deformation.
    However,
    (J9 / J1.5) = (hardness at a distance of 9 mm from the quenching end measured by the Jomini type one-end quenching method) ÷ (1.5 mm from the quenching end measured by the Jominy type one-end quenching method) (Hardness) …… (1)
    (J11 / J1.5) = (hardness at a distance of 11 mm from the quenching end measured by the Jomini type one-end quenching method) ÷ (a distance of 1.5 mm from the quenching end measured by the Jominy type one-end quenching method) (Hardness) …… (2)
  4. 　質量％で、
    　Ｃ：０．２０～０．３０％、
    　Ｓｉ：０．１０～１．５０％、
    　Ｍｎ：０．１０～１．２０％、
    　Ｐ：０．０３０％以下、
    　Ｓ：０．０３０％以下、
    　Ｃｒ：１．３０～２．５０％、
    　Ｃｕ：０．３０％以下、
    　Ａｌ：０．００８～０．３００％、
    　Ｏ：０．００３０％以下、
    　Ｎ：０．００２０～０．０３００％を含有し、
    　さらにＮｉ：０．２０～３．００％およびＭｏ：０．０５～０．５０％の１種または２種を含有し、
    　さらにＴｉ：０．０２０～０．２００％およびＮｂ：０．０２～０．２０％の１種または２種を含有し、
    　残部Ｆｅおよび不可避不純物からなる機械構造用鋼であり、
    　該鋼からなる鋼材のマルテンサイト変態開始温度（Ｍｓ点）が４６０℃以下であり、
    　該鋼材についてジョミニー式一端焼入法により測定される鋼材の焼入端からの距離１．５ｍｍにおける硬さのＪ１．５および距離９ｍｍにおける硬さのＪ９を用いて、下記の式（１）によって算出した（Ｊ９／Ｊ１．５）の値が０．７０～０．８５の範囲にあり、
    　さらに距離１．５ｍｍにおける硬さのＪ１．５および距離１１ｍｍにおける硬さのＪ１１を用いて、下記の式（２）によって算出した（Ｊ１１／Ｊ１．５）の値が０．６７～０．７８の範囲にある、
    　熱処理変形の小さい機械構造用鋼材。
    　ただし、
    　（Ｊ９／Ｊ１．５）＝（ジョミニー式一端焼入法により測定される焼入れ端からの距離９ｍｍの硬さ）÷（ジョミニー式一端焼入法により測定される焼入れ端からの距離１．５ｍｍの硬さ）……（１）
    　（Ｊ１１／Ｊ１．５）＝（ジョミニー式一端焼入法により測定される焼入れ端からの距離１１ｍｍの硬さ）÷（ジョミニー式一端焼入法により測定される焼入れ端からの距離１．５ｍｍの硬さ）……（２）     % By mass
    C: 0.20 to 0.30%
    Si: 0.10 to 1.50%,
    Mn: 0.10 to 1.20%,
    P: 0.030% or less,
    S: 0.030% or less,
    Cr: 1.30-2.50%,
    Cu: 0.30% or less,
    Al: 0.008 to 0.300%,
    O: 0.0030% or less,
    N: 0.0020 to 0.0300% is contained,
    Furthermore, it contains one or two of Ni: 0.20 to 3.00% and Mo: 0.05 to 0.50%,
    Furthermore, it contains one or two of Ti: 0.020-0.200% and Nb: 0.02-0.20%,
    It is a steel for machine structure consisting of the balance Fe and inevitable impurities,
    The martensitic transformation start temperature (Ms point) of the steel material made of the steel is 460 ° C. or less,
    With respect to the steel material, J1.5 of hardness at a distance of 1.5 mm from the quenching end of the steel material measured by the Jominy type one-end quenching method and J9 of hardness at a distance of 9 mm are used according to the following formula (1). The calculated (J9 / J1.5) value is in the range of 0.70 to 0.85,
    Further, using the hardness J1.5 at a distance of 1.5 mm and the hardness J11 at a distance of 11 mm, the value of (J11 / J1.5) calculated by the following equation (2) is 0.67 to 0.78. In the range of
    Machine structural steel with small heat treatment deformation.
    However,
    (J9 / J1.5) = (hardness at a distance of 9 mm from the quenching end measured by the Jomini type one-end quenching method) ÷ (1.5 mm from the quenching end measured by the Jominy type one-end quenching method) (Hardness) …… (1)
    (J11 / J1.5) = (hardness at a distance of 11 mm from the quenching end measured by the Jomini type one-end quenching method) ÷ (a distance of 1.5 mm from the quenching end measured by the Jominy type one-end quenching method) (Hardness) …… (2)
PCT/JP2013/073681 2012-09-04 2013-09-03 Machine structure steel material having low heat-treatment deformation WO2014038548A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
KR1020157006758A KR20150047524A (en) 2012-09-04 2013-09-03 Machine structure steel material having low heat-treatment deformation
US14/425,420 US20150218682A1 (en) 2012-09-04 2013-09-03 Machine Structural Steel Material Having Low Heat-Treatment Deformation

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2012-193763 2012-09-04
JP2012193763A JP6057626B2 (en) 2012-09-04 2012-09-04 Machine structural steel with low heat treatment deformation

Publications (1)

Publication Number Publication Date
WO2014038548A1 true WO2014038548A1 (en) 2014-03-13

Family

ID=50237157

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2013/073681 WO2014038548A1 (en) 2012-09-04 2013-09-03 Machine structure steel material having low heat-treatment deformation

Country Status (4)

Country Link
US (1) US20150218682A1 (en)
JP (1) JP6057626B2 (en)
KR (1) KR20150047524A (en)
WO (1) WO2014038548A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104404224A (en) * 2014-12-15 2015-03-11 南车长江车辆有限公司 Heat treatment process method for EA1N-material urban rail car axle
CN110777303A (en) * 2019-12-04 2020-02-11 宝钢特钢韶关有限公司 Round steel for gear and preparation method thereof

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101705168B1 (en) * 2015-04-20 2017-02-10 현대자동차주식회사 Carburizing alloy steel improved durability and the method of manufacturing the same
CN109971929A (en) * 2019-04-16 2019-07-05 中南大学 It is a kind of high throughput material preparation and performance characterization system

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001262203A (en) * 2000-03-22 2001-09-26 Daido Steel Co Ltd High hardness gas atomizing shot
JP2003055734A (en) * 2001-08-10 2003-02-26 Daido Steel Co Ltd Austenitic tool steel having excellent machinability and method for producing austenitic tool
JP2010150566A (en) * 2008-12-24 2010-07-08 Sumitomo Metal Ind Ltd Steel for vacuum carburizing or vacuum carbo-nitriding
JP2011225936A (en) * 2010-04-20 2011-11-10 Daido Steel Co Ltd Carbonitrided steel of hydrogen embrittlement type having excellent surface fatigue strength
JP2013040364A (en) * 2011-08-12 2013-02-28 Nippon Steel & Sumitomo Metal Corp Rolled steel bar or wire rod for hot forging

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS56116857A (en) * 1980-02-20 1981-09-12 Mitsubishi Steel Mfg Co Ltd Low-heat treated strained steel for gear
JP5185852B2 (en) * 2009-02-13 2013-04-17 株式会社神戸製鋼所 Gears with excellent resistance to peeling damage
JP5350181B2 (en) * 2009-10-27 2013-11-27 株式会社神戸製鋼所 Case-hardened steel with excellent grain coarsening prevention properties
WO2012073485A1 (en) * 2010-11-30 2012-06-07 Ｊｆｅスチール株式会社 Carburizing steel having excellent cold forgeability, and production method thereof

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001262203A (en) * 2000-03-22 2001-09-26 Daido Steel Co Ltd High hardness gas atomizing shot
JP2003055734A (en) * 2001-08-10 2003-02-26 Daido Steel Co Ltd Austenitic tool steel having excellent machinability and method for producing austenitic tool
JP2010150566A (en) * 2008-12-24 2010-07-08 Sumitomo Metal Ind Ltd Steel for vacuum carburizing or vacuum carbo-nitriding
JP2011225936A (en) * 2010-04-20 2011-11-10 Daido Steel Co Ltd Carbonitrided steel of hydrogen embrittlement type having excellent surface fatigue strength
JP2013040364A (en) * 2011-08-12 2013-02-28 Nippon Steel & Sumitomo Metal Corp Rolled steel bar or wire rod for hot forging

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104404224A (en) * 2014-12-15 2015-03-11 南车长江车辆有限公司 Heat treatment process method for EA1N-material urban rail car axle
CN110777303A (en) * 2019-12-04 2020-02-11 宝钢特钢韶关有限公司 Round steel for gear and preparation method thereof

Also Published As

Publication number Publication date
JP6057626B2 (en) 2017-01-11
KR20150047524A (en) 2015-05-04
JP2014047419A (en) 2014-03-17
US20150218682A1 (en) 2015-08-06

Similar Documents

Publication Publication Date Title
US8894778B2 (en) Carburized and high-frequency hardened part having high strength
JP5123335B2 (en) Crankshaft and manufacturing method thereof
US20130186522A1 (en) Carburizing steel having excellent cold forgeability and method of manufacturing the same
WO2012144423A1 (en) Steel material for machine structural use having excellent contact pressure fatigue strength
CN112292471B (en) Mechanical component
WO2011122134A1 (en) Steel for high frequency hardening, roughly molded material for high frequency hardening and process for production thereof, and high-frequency-hardened steel member
WO2013024876A1 (en) Spring steel and spring
JP5804832B2 (en) Steel material made of carburizing steel with excellent torsional fatigue properties
JP6057626B2 (en) Machine structural steel with low heat treatment deformation
JP5641992B2 (en) Machine structural steel with low heat treatment deformation
JP4488228B2 (en) Induction hardening steel
JP4728884B2 (en) Induction contour hardened steel and induction contour hardened parts with excellent low cycle fatigue characteristics
JP5583352B2 (en) Induction hardening steel and induction hardening parts with excellent static torsional fracture strength and torsional fatigue strength
KR20190076694A (en) Steel wire rod for cold forging and methods for manufacturing thereof
JP7149179B2 (en) Mechanical parts for automobiles made of induction hardened steel with excellent static torsional strength and torsional fatigue strength
JP2009191322A (en) Case-hardened steel superior in grain-coarsening resistance for use in carburized parts
JP5641991B2 (en) Machine structural steel with low heat treatment deformation
JP6447064B2 (en) Steel parts
JP5505264B2 (en) Induction contour hardened steel and induction contour hardened parts with excellent low cycle fatigue characteristics
JP5131770B2 (en) Non-tempered steel for soft nitriding
KR101984041B1 (en) Case hardening steel
JP7175182B2 (en) Automobile mechanical parts made of carburizing steel with excellent static torsional strength and torsional fatigue strength
WO2022137697A1 (en) Case hardened steel for warm forging and forged blank manufactured using same
JP6197761B2 (en) Manufacturing method of cold processed products
JP2022148091A (en) steel member

Legal Events

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

Ref document number: 13834664

Country of ref document: EP

Kind code of ref document: A1

WWE Wipo information: entry into national phase

Ref document number: 14425420

Country of ref document: US

NENP Non-entry into the national phase

Ref country code: DE

ENP Entry into the national phase

Ref document number: 20157006758

Country of ref document: KR

Kind code of ref document: A

122 Ep: pct application non-entry in european phase

Ref document number: 13834664

Country of ref document: EP

Kind code of ref document: A1