[go: up one dir, main page]

WO2018155588A1 - Procédé de fabrication d'élément de palier - Google Patents

Procédé de fabrication d'élément de palier Download PDF

Info

Publication number
WO2018155588A1
WO2018155588A1 PCT/JP2018/006574 JP2018006574W WO2018155588A1 WO 2018155588 A1 WO2018155588 A1 WO 2018155588A1 JP 2018006574 W JP2018006574 W JP 2018006574W WO 2018155588 A1 WO2018155588 A1 WO 2018155588A1
Authority
WO
WIPO (PCT)
Prior art keywords
tempering
target material
manufacturing
bearing
quenching
Prior art date
Legal status (The legal status 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 status listed.)
Ceased
Application number
PCT/JP2018/006574
Other languages
English (en)
Japanese (ja)
Inventor
美有 佐藤
敬史 結城
大木　力
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NTN Corp
Original Assignee
NTN Corp
NTN Toyo Bearing Co Ltd
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
Priority claimed from JP2017033677A external-priority patent/JP2018138686A/ja
Priority claimed from JP2017033670A external-priority patent/JP2018138685A/ja
Application filed by NTN Corp, NTN Toyo Bearing Co Ltd filed Critical NTN Corp
Publication of WO2018155588A1 publication Critical patent/WO2018155588A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Images

Classifications

    • 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
    • C21D9/40—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rings; for bearing races

Definitions

  • the present invention relates to a method for manufacturing a bearing component.
  • Japanese Patent Application Laid-Open No. 2013-119930 discloses a method for manufacturing a bearing component, which includes a step of quenching and hardening a molded member and a step of tempering the molded member that has been quenched and hardened.
  • the tempering treatment is an important heat treatment from the viewpoints of imparting toughness, adjusting hardness, removing residual stress, and improving dimensional stability for the bearing parts.
  • the holding time of the tempering temperature in the tempering process is relatively long, for example, about 2 hours, and there is a problem in productivity.
  • productivity can be expected to be improved by using high-temperature and short-time treatment for the tempering treatment in the bearing component manufacturing method.
  • the present invention has been made to solve the above-described problems.
  • the main object of the present invention is to shorten the processing time as compared with a conventional method for manufacturing a bearing component that performs tempering for a long time, and further, it is equivalent to a bearing component obtained by the above-described conventional method for manufacturing a bearing component.
  • An object of the present invention is to provide a method of manufacturing a bearing component having the above material characteristics.
  • a method for manufacturing a bearing component includes a step of preparing a target material made of high carbon chromium bearing steel and to be a bearing component, and a step of performing a quenching process on the target material. And a step of tempering the target material after the step of quenching.
  • the quenching process is performed so that the hardness of the target material is 64 HRC or more and 66 HRC or less.
  • the tempering temperature T (unit: K) and the holding time t (unit: second) in the tempering process satisfy the following formula (1).
  • a method for manufacturing a bearing component according to another embodiment of the present invention is a method for manufacturing a bearing component, comprising a step of preparing a target material made of high carbon chromium bearing steel and to be a bearing component, and a target material And a step of performing a tempering process on the target material by heating the target material after the step of performing the quenching process on the steel and the step of performing the quenching process.
  • the tempering temperature T (unit: K) and the holding time t (unit: second) in the tempering process satisfy the following formula (2).
  • the time required for the tempering process can be shortened as compared with the conventional method for manufacturing a bearing part that performs a tempering process for a long time. Furthermore, according to the present invention, it is possible to provide a method of manufacturing a bearing component having material characteristics equivalent to or higher than those of the bearing component obtained by the conventional method of manufacturing a bearing component.
  • 2 is a flowchart of a method for manufacturing a bearing component according to the first embodiment.
  • the manufacturing method of the bearing component concerning Embodiment 1 it is a graph which shows the tempering temperature and holding time of the 2nd heating process (tempering process).
  • 6 is a graph showing static crushing strength in Example 2.
  • 10 is a graph showing stress amplitude in Example 2.
  • the manufacturing method of the bearing parts concerning Embodiment 2 it is a graph for explaining the tempering temperature and maintenance time which satisfy the 1st prediction formula.
  • the manufacturing method of the bearing component concerning Embodiment 2 it is a graph for explaining the tempering temperature and holding time which satisfy the 2nd prediction formula.
  • the manufacturing method of the bearing component concerning Embodiment 2 it is a graph for explaining the tempering temperature and maintenance time which satisfy formula (2).
  • the method for manufacturing a bearing component according to the first embodiment includes a step of preparing a molded body (target material) to be the inner ring (bearing component) (S10) and a step of performing a quench hardening process on the target material. (S20) and the process (S30) of performing a tempering process with respect to a target material after the process (S20) of performing a quench hardening process.
  • a steel material such as a steel bar or a steel wire is prepared.
  • the steel material is made of SUJ2, for example.
  • the steel material is subjected to processing such as cutting, forging, and turning.
  • a steel material (target material) formed into a rough shape of a bearing component such as a bearing ring for a rolling bearing is produced.
  • Step (S20) a quench hardening process is performed on the target material prepared in the previous step (S10).
  • Step (S20) includes a first heating step (S21) and a cooling step (S22).
  • the entire target material is heated to a temperature T 1 that is equal to or higher than the A 1 point, and is held for a holding time t 1 for soaking.
  • the target material is cooled to a temperature T 2 that is equal to or lower than the Ms point (martensitic transformation point).
  • This cooling process is performed by, for example, immersing the target material in a coolant such as oil or water. Thereby, the said target material is quenching-processed.
  • the quenching process is performed under the condition that the hardness of the target material subjected to the quenching process exceeds the hardness of the target material subjected to the tempering process described later.
  • the quenching process is performed, for example, under conditions such that the hardness of the target material subjected to the quenching process is 64 HRC (800 HV) or more and 66 HRC (865 HV) or less.
  • the temperatures T 1 is less than 1000 ° C. For example 900 ° C. or higher.
  • the holding time t 1 (homogeneous time) is, for example, not less than 3 seconds and not more than 10 minutes.
  • the temperature T 2 is, for example, not less than 80 ° C. and not more than 200 ° C.
  • the quenching process is performed under conditions such that the carbide area ratio of the target material subjected to the quenching process is 8% or more and 12% or less.
  • the holding time t 1 is preferably 11 seconds or longer so that the carbide area ratio of the quenched target material is 12% or less, and the carbide area ratio is 8
  • the holding time t 1 is preferably 58 seconds or less so as to be not less than%.
  • the holding time t 1 is preferably 3 seconds or more so that the carbide area ratio of the quench-treated target material is 12% or less, and the carbide area ratio is 8% or more.
  • the holding time t 1 is preferably 15 seconds or less. That is, when the temperature T 1 is 950 ° C., the holding time t 1 is preferably 3 seconds or longer and 15 seconds or shorter.
  • the rapid cooling of the target material is performed by, for example, immersing the target material in cold oil having an oil temperature of 70 ° C.
  • a tempering process is performed on the target material that has been subjected to the quench hardening process in the previous process (S20).
  • the entire target material is heated to a tempering temperature T 3 less than A 1 point, and is held for a holding time t 2 for soaking.
  • the target material is cooled. Thereby, the said target material is tempered.
  • the tempering process is performed under such a condition that the hardness of the tempered target material is less than the hardness of the tempered target material.
  • the tempering process is performed under conditions such that the hardness of the tempered target material is 60 HRC (696 HV) or more and 62 HRC (746 HV) or less.
  • the tempering temperature T 3 (unit: K) and the holding time t 2 (unit: second) of the tempering process satisfy the following formula (1).
  • Formula (3) shows the relationship between the tempering temperature T 3 (unit: K), the holding time t 2 (unit: second) of the tempering process, and the hardness (unit: HRC) of the target material after the tempering process. It is a formula. Equation (3) is shown in Non-Patent Document 1 (Akira Inoue, “New tempering parameters and their application to the integration method of tempering effects along a continuous temperature rise curve” Iron and Steel, 66, 10 (1980) 1533. ).
  • FIG. 2 is a graph for explaining the tempering temperature T 3 and the holding time t 2 satisfying the expression (1).
  • the horizontal axis of FIG. 2 shows the tempering temperature T 3 (unit: K), and the vertical axis of FIG. 2 shows the holding time t 2 (unit: second).
  • T 3 unit: K
  • T 2 unit: second
  • lines L1 to L5 indicate the relationship between the tempering temperature T 3 and the holding time t 2 in the equation (3) including constants a, b, c calculated from bearing parts having different hardnesses. It is a curve which shows.
  • the tempering temperature T 3 and the holding time t 2 of the tempering process can be arbitrarily selected from coordinates located on the line L2 and the line L4 in FIG. 2 and between the line L2 and the line L4.
  • a finishing process is performed as a process (S40).
  • this step (S40) for example, finishing such as polishing is performed on the rolling surface.
  • the method for manufacturing a bearing component according to the present embodiment a tempering process at a high temperature for a short time is performed. Therefore, according to the method for manufacturing a bearing component according to the present embodiment, compared with the conventional method for manufacturing a bearing component in which the tempering process is performed for several hours, the retention time in the tempering process is the manufacturing of the conventional bearing part. Short compared to the method. As a result, according to the bearing component manufacturing method according to the present embodiment, the manufacturing cost is reduced as compared with the conventional bearing component manufacturing method.
  • the quenching process is performed in the quenching process (S20) so that the carbide area ratio of the target material is 8% or more and 12% or less.
  • the dimensional change rate of bearing parts is influenced by the concentration of carbon (carbon solid solution amount) dissolved in the matrix of the target material by the quenching process.
  • carbon solid solution amount concentration of carbon
  • the area ratio of carbides in the target material reflects the solid solution state of carbon in the target material. Therefore, the area ratio of carbides in the target material can be used to accurately predict the solid solution state of carbon in the target material.
  • the carbide area ratio of the target material is measured, for example, by cutting the target material that has been heat-treated and measuring the area ratio of the carbide in the cross section with an electron microscope.
  • a normalizing step may be performed before the quench hardening step.
  • the normalizing step after the fabricated molded body is heated to a temperature not lower than the A 1 transformation point in the step (S10), normalizing processing is performed by being cooled to a temperature lower than the A 1 transformation point.
  • the cooling rate at the time of cooling in the normalizing process may be a cooling rate at which the steel constituting the formed body is not transformed into martensite, that is, a cooling rate lower than the critical cooling rate.
  • the hardness of the molded body after the normalizing treatment is high when the cooling rate is large, and is low when the cooling rate is small. Therefore, desired hardness can be imparted to the molded body by adjusting the cooling rate.
  • the shaft house part is not limited to the inner ring of the rolling bearing. It may be an outer ring or a rolling element of a rolling bearing, or may be an inner ring, an outer ring, or a rolling element of a deep groove ball bearing or a thrust needle roller bearing.
  • the method for manufacturing a bearing component according to the second embodiment includes a step of preparing a molded body (target material) to be the inner ring (bearing component) (S10) and a step of performing a quench hardening process on the target material. (S20) and the process (S30) of performing a tempering process with respect to a target material by heating a target material after the process (S20) of performing a quench hardening process.
  • a steel material such as a steel bar or a steel wire is prepared.
  • the steel material is made of SUJ2, for example.
  • the steel material is subjected to processing such as cutting, forging, and turning.
  • a steel material (target material) formed into a rough shape of a bearing component such as a bearing ring for a rolling bearing is produced.
  • Step (S20) a quench hardening process is performed on the target material prepared in the previous step (S10).
  • Step (S20) includes a first heating step (S21) and a cooling step (S22).
  • the entire target material is heated to a temperature T 1 that is equal to or higher than the point A 1 and is held for a holding time t 1 (soaking time) for soaking.
  • the target material is cooled to a temperature T 2 that is equal to or lower than the Ms point (martensitic transformation point).
  • This cooling process is performed by, for example, immersing the target material in a coolant such as oil or water. Thereby, the said target material is quenching-processed.
  • the quenching process is performed under the condition that the hardness of the target material subjected to the quenching process exceeds the hardness of the target material subjected to the tempering process described later.
  • the quenching process is performed, for example, under conditions such that the hardness of the target material subjected to the quenching process is 64 HRC (800 HV) or more and 66 HRC (865 HV) or less.
  • the temperatures T 1 is less than 1000 ° C. For example 900 ° C. or higher.
  • the holding time t 1 is not less than 1 second and not more than 10 minutes, for example.
  • the temperature T 2 is, for example, not less than 50 ° C. and not more than 200 ° C.
  • the quenching process is performed under conditions such that the carbide area ratio of the target material subjected to the quenching process is 8% or more and 12% or less.
  • the holding time t 1 is preferably 11 seconds or longer so that the carbide area ratio of the quenched target material is 12% or less, and the carbide area ratio is 8
  • the holding time t 1 is preferably 58 seconds or less so as to be not less than%.
  • the holding time t 1 is preferably 3 seconds or more so that the carbide area ratio of the quench-treated target material is 12% or less, and the carbide area ratio is 8% or more.
  • the holding time t 1 is preferably 15 seconds or less. That is, when the temperature T 1 is 950 ° C., the holding time t 1 is preferably 3 seconds or longer and 15 seconds or shorter.
  • the rapid cooling of the target material is performed by, for example, immersing the target material in cold oil having an oil temperature of 70 ° C.
  • a tempering process is performed on the target material that has been subjected to the quench hardening process in the previous process (S20).
  • the entire target material is heated to a tempering temperature T 3 less than the point A 1 and is held for a holding time t 2 (tempering time) for soaking.
  • the tempering temperature T 3 (unit: K) and the holding time t 2 (unit: second) of the tempering process satisfy the following relational expression (2).
  • Equation (4) is the relationship between the tempering temperature T 3 (unit: K), the holding time t 2 (unit: second), and the hardness M 1 (unit: HV) of the target material after tempering. It is a formula which shows. Equation (4) is shown in Non-Patent Document 1 (Akira Inoue, “New tempering parameters and their application to an integrating method of tempering effects along a continuous temperature rise curve” Iron and Steel, 66, 10 (1980) 1533. )It is described in.
  • Formula (5) is the tempering temperature T 3 (unit: K) of the tempering treatment, the holding time t 2 (unit: second), and the amount of retained austenite M 2 (unit:%) of the target material after the tempering treatment. It is a formula which shows a relationship. Expression (5) is described in Patent Document 2 (Japanese Patent Laid-Open No. 10-102137).
  • M 2 M 0 exp ⁇ Aexp (( ⁇ Q) / RT 3 ) t 2 n ⁇ (5)
  • the inventors experimentally derived the constants a, b, c in the equation (4) and the constants M 0 , A, Q, n in the equation (5).
  • the derived constant a was ⁇ 26.4
  • the constant b was 2.00 ⁇ 10 5
  • the constant c was 408.
  • the derived constant M 0 was 14.4, the constant A was 6.99 ⁇ 10 5 , the constant Q was 7.70 ⁇ 10 4 , and the constant n was 0.510.
  • the above formula (4) in which the constants a, b, and c are specified in this way is a first prediction formula for predicting the relationship between the tempering process conditions and the hardness M 1 after the tempering process.
  • the above equation (5) in which the constants M 0 , A, Q, and n are specified in this way is a second prediction equation for predicting the relationship between the tempering treatment conditions and the amount of retained austenite M 2 after the tempering treatment. It becomes.
  • FIG. 5 is a graph for explaining the tempering temperature T 3 and the holding time t 2 satisfying the first prediction formula.
  • FIG. 6 is a graph for explaining the tempering temperature T 3 and the holding time t 2 satisfying the second prediction formula.
  • FIG. 7 is a graph for explaining the tempering temperature T 3 and the holding time t 2 that satisfy the equation (2) calculated based on the first prediction equation and the second prediction equation.
  • Each horizontal axis in FIGS. 5 to 7 represents the tempering temperature T 3 (unit: K), and each vertical axis in FIGS. 5 to 7 represents the holding time t 2 (unit: seconds).
  • lines L1 to L3 are curves showing the relationship between the tempering temperature T 3 and the holding time t 2 that satisfy the first prediction formula.
  • Line L1 is a line showing predicted values of tempering temperature T 3 and holding time t 2 for obtaining a bearing component of 60HRC
  • line L2 is 61HRC
  • line L3 is 62HRC.
  • the predicted value of the tempering temperature T 3 for obtaining a bearing component having a hardness of 59 HRC is 320 ° C. or higher when the holding time t 2 is 0 second or longer and 300 seconds or shorter. there were.
  • lines L4 to L6 are curves showing the relationship between the tempering temperature T 3 and the holding time t 2 satisfying the second prediction formula.
  • Line L4 residual austenite amount is 3%
  • the line L5 is the amount of retained austenite 4%
  • the line L6 is the predicted value of the tempering temperature T 3 and the holding time t 2 for the amount of retained austenite obtain a bearing part is 5% It is a line which shows.
  • Tempering temperature T 3 and the holding time t 2 of the tempering process for example on line L5 in FIG. 7, and tempering temperature T 3 is longer holding time t 2 than the high temperature side or line L5, than the line L5 It can be arbitrarily selected from the coordinates located on the side.
  • the retention time t 2 is 300 seconds or less.
  • a finishing process is performed as a process (S40).
  • this step (S40) for example, finishing such as polishing is performed on the rolling surface.
  • the method for manufacturing a bearing component according to the present embodiment a tempering process at a high temperature for a short time is performed. Therefore, according to the method for manufacturing a bearing component according to the present embodiment, the tempering process has a shorter holding time in the tempering process than the conventional method for manufacturing a bearing part compared to the conventional method for manufacturing a bearing part. Furthermore, the enlargement of the heating device is suppressed. As a result, according to the bearing component manufacturing method according to the present embodiment, the manufacturing cost is reduced as compared with the conventional bearing component manufacturing method.
  • the tempering temperature T 3 (unit: K) and the holding time t 2 (unit: second) in the tempering process are expressed by the above formula (2).
  • the above formula (2) shows that the present inventor can obtain a bearing part having a hardness equal to or higher than that of a conventional bearing part and a residual austenite amount equal to or lower than that of a conventional bearing part by tempering. Have been experimentally calculated (details will be described later). Therefore, a book obtained by subjecting a target material made of JIS standard SUJ2 to a tempering treatment at a tempering temperature T 3 (unit: K) and a holding time t 2 (unit: second) satisfying the above formula (2).
  • the bearing component according to the embodiment has a hardness equal to or higher than that of a conventional bearing component and a dimensional change rate equal to or lower than that of a conventional bearing component.
  • the high carbon chrome bearing steel is JIS standard SUJ2.
  • the bearing component manufacturing method according to the present embodiment is suitable for a bearing component manufacturing method comprising JIS standard SUJ2.
  • the holding time t 2 (tempering time) is preferably within 300 seconds.
  • the tempering time is relatively long, for example, about 2 hours to 5 hours.
  • the holding time t 2 (tempering time) can be within 300 seconds.
  • the holding time in the tempering process is shorter than the conventional bearing component manufacturing method, and the manufacturing cost is reduced, compared with the conventional bearing component manufacturing method. ing.
  • the present inventors have confirmed that the steel material that has been subjected to such a tempering treatment has the hardness required for the bearing component (details will be described later). Furthermore, the present inventors have confirmed that the steel material subjected to such tempering treatment has a retained austenite amount capable of realizing a dimensional change rate required for the bearing component (details will be described later). To do).
  • a normalizing step may be performed before the quench hardening step.
  • the normalizing step after the fabricated molded body is heated to a temperature not lower than the A 1 transformation point in the step (S10), normalizing processing is performed by being cooled to a temperature lower than the A 1 transformation point.
  • the cooling rate at the time of cooling in the normalizing process may be a cooling rate at which the steel constituting the formed body is not transformed into martensite, that is, a cooling rate lower than the critical cooling rate.
  • the hardness of the molded body after the normalizing treatment is high when the cooling rate is large, and is low when the cooling rate is small. Therefore, desired hardness can be imparted to the molded body by adjusting the cooling rate.
  • the bearing component is not limited to the inner ring of the rolling bearing. It may be an outer ring or a rolling element of a rolling bearing, or may be an inner ring, an outer ring, or a rolling element of a deep groove ball bearing or a thrust needle roller bearing.
  • test piece made of JIS standard SUJ2 was prepared.
  • Table 1 shows the component composition of the test piece.
  • the test piece was quenched.
  • the quenching temperature T 1 was 900 ° C. or more and 950 ° C. or less
  • the holding time t 1 was 3 seconds or more and 60 seconds or less
  • the temperature T 2 was 100 ° C.
  • the Vickers hardness was measured using a Vickers hardness tester.
  • the Vickers hardness measured for samples 1 to 14 is shown in the column of measured hardness in Table 2.
  • the constants a, b, and c were calculated by substituting the tempering temperature T 3 , the holding time T 2 , and the measured hardness for the samples 1 to 14. From the distribution of the calculated values of constants a, b, and c, the sum of the differences between the hardness (estimated hardness) obtained by substituting the values of constants a, b, and c into equation (3) and the measured hardness is minimum. As a result, it was confirmed that the constant a was ⁇ 19.6, the constant b was 2.21 ⁇ 10 5 , and the constant c was 347.
  • the characteristics required for the bearing parts were evaluated for the samples obtained by the same method as the method for manufacturing the bearing parts according to the first embodiment.
  • test piece made of JIS standard SUJ2 was prepared.
  • the component composition of the test piece is as shown in Table 1 above.
  • the shape of the test piece was annular.
  • the dimensions of the test piece were an outer diameter of 60 mm, an inner diameter of 54 mm, and an axial width of 15 mm.
  • the samples 15 to 27 according to the examples were prepared by subjecting the test pieces to quenching and tempering.
  • Table 3 shows the quenching and tempering conditions for Samples 15 to 27.
  • test piece was subjected to quenching so that the carbide area ratio after quenching was 8% or 12%.
  • Samples 15 to 17 were subjected to a quenching process under the conditions of a temperature T 1 of 900 ° C. and a holding time t 1 of 58 seconds so that the carbide area ratio of the test piece after the quenching process was 8%. is there.
  • Samples 21 to 23 were subjected to a quenching process under the conditions of a temperature T 1 of 950 ° C. and a holding time t 1 of 15 seconds so that the carbide area ratio of the test piece after the quenching process was 8%. is there.
  • Samples 18 to 20 were subjected to quenching treatment under the conditions of a temperature T 1 of 900 ° C. and a holding time t 1 of 11 seconds so that the carbide area ratio of the above-mentioned specimen after quenching treatment was 12%. It is. Samples 24 to 26 were subjected to quenching treatment under the conditions of a temperature T 1 of 950 ° C. and a holding time t 1 of 3 seconds so that the carbide area ratio of the test piece after quenching treatment was 12%. is there.
  • Samples 15 to 26 were obtained by tempering the specimens quenched as described above so that the hardness after tempering was 60 HRC or 62 HRC.
  • Samples 15, 18, 21, and 24 were tempered under conditions of a tempering temperature T 3 of 180 ° C. and a time t 2 of 7200 seconds so that the hardness after tempering was 62 HRC.
  • Samples 16, 19, 22, and 25 were tempered under conditions of a tempering temperature T 3 of 240 ° C. and a time t 2 of 43 seconds so that the hardness after tempering was 62 HRC.
  • Samples 17, 20, 23, and 26 were tempered under conditions of a tempering temperature T 3 of 310 ° C. and a time t 2 of 37 seconds so that the hardness after tempering was 60 HRC.
  • Sample 27 as a comparative example was tempered so that the hardness after tempering was 62 HRC after quenching so that the carbide area ratio of the test piece after quenching was 8%. It is a thing.
  • the quenching temperature was 850 ° C. and the holding time was 30 minutes.
  • the tempering temperature was 180 ° C. and the holding time was 7200 seconds.
  • ⁇ Dimensional change rate> The dimensional change rates of Samples 15 to 27 were evaluated as follows. Samples 15 to 27 were heated to 230 ° C. and held for 2 hours, and the dimensional change rate before and after heating was calculated for each sample. Table 4 shows the average values of the dimensional change rates of Samples 15 to 17, Samples 18 to 20, Samples 21 to 23, and Samples 24 to 26 produced under the same quenching treatment conditions.
  • Non-Patent Document 2 (Norioka Sakanaka et al., “Rapid evaluation of shear fatigue properties of rolling bearing steels up to ultra-long life” NTN) TECHNIC REVIEW, 79 (2011) 104.).)
  • the load frequency was 20 kHz.
  • An intermittent loading method was used in which loading and rest were alternately repeated.
  • the maximum number of loads was 10 10 times. If the load did not break even when the number of loadings reached 10 10 times, the evaluation was terminated. In this way, the relationship between the number of loadings and the stress amplitude was obtained for samples 15 to 27.
  • An SN graph was created by applying the obtained values to a fatigue limit type broken line model of JSMS-SD-6-02, a metal material fatigue reliability standard of the Japan Society of Materials Science.
  • FIG. 4 shows the stress amplitude required for the samples 15 to 27 to be damaged when the number of times of loading is 3 ⁇ 10 9 derived from the above relationship. Note that the bar in FIG. 4 indicates the standard deviation of the stress amplitude calculated from the above model.
  • the number of loads of 3 ⁇ 10 9 times is the number of loads at which fatigue failure can occur when a life test is performed with the maximum contact surface pressure Pmax being 2.5 GPa.
  • the upper limit value of the stress amplitude required for damaging the samples 15 to 27 when the number of times of loading is 3 ⁇ 10 9 times is defined as the shear fatigue strength of the samples 15 to 27.
  • test piece made of JIS standard SUJ2 was prepared.
  • the component composition of the test piece is equivalent to that shown in Table 1 above.
  • the test piece was quenched.
  • the quenching temperature T 1 was 950 ° C., and the holding time t 1 was 15 seconds. After holding time t 1 , the test piece was immersed in cold oil having an oil temperature of 70 ° C. and quenched and cooled.
  • the temperature T 2 was about 100 ° C.
  • the hardness of the test piece after the quenching treatment was 64.5 HRC, and the amount of retained austenite of the test piece was 14.7%.
  • tempering treatment was performed on the test piece subjected to the quenching treatment.
  • the tempering conditions were 15 conditions shown in Table 5.
  • samples 28 to 42 tempered under different conditions were produced.
  • Fifteen tempering treatment conditions are five tempering temperatures T 3 240 ° C., 260 ° C., 280 ° C., 300 ° C., 320 ° C., and three holding times t 2 19 seconds, 74 seconds, 300 seconds. It was a combination.
  • Vickers hardness was measured using a Vickers hardness tester on samples 28 to 42 that had been tempered. Further, the amount of retained austenite was measured for the samples 28 to 42 subjected to the tempering treatment using an X-ray diffractometer. Table 5 shows the tempering conditions, the measured Vickers hardness, and the amount of retained austenite for Samples 28 to 42.
  • Equation (4) in which the constants a, b, and c are specified in this manner is a first prediction equation for predicting the relationship between the tempering treatment conditions and the hardness after the tempering treatment.
  • Each of the lines L1 to L3 in FIGS. 5 and 7 indicates tempering processing conditions for obtaining a bearing component having a predetermined hardness based on the first prediction formula.
  • the tempering temperature T 3 , the holding time t 2 , and the actual measurement values of the retained austenite amount of the samples 28 to 42 are substituted into the constants T, t, M in the equation (5), and the constants M 0 , A, Q, n was calculated.
  • the constant M 0 is 14.4
  • the constant A is 6.99 ⁇ 10 5
  • the constant Q is 7.70 ⁇ 10 4
  • the constant n is 0.510. confirmed.
  • the constant M 0 means the amount of retained austenite of each sample before tempering.
  • Equation (5) in which the constants M 0 , A, Q, and n are specified in this way is a second prediction equation for predicting the relationship between the tempering treatment conditions and the amount of retained austenite after the tempering treatment. .
  • Each of lines L4 to L6 in FIG. 6 and FIG. 7 indicates tempering conditions for obtaining a bearing component having a predetermined retained austenite amount based on the second prediction formula.
  • formula (2) is derived as showing the tempering treatment conditions for the hardness after tempering to be 59 HRC or more (674 HV or more) and the amount of retained austenite after tempering to be 4% or less. did.
  • the tempering temperature T 3 and the holding time t 2 satisfying the expression (2) are shown as coordinates located on the line 5 and on the upper side of the vertical axis from the line 5 (right side on the horizontal axis). ing.
  • the tempering process conditions shown by Formula (2) have the hardness more than equivalent to the rolling bearing obtained by the manufacturing method of the said conventional rolling bearing, and have the amount of residual austenite equivalent to or less than the said rolling bearing. This is a condition for manufacturing a rolling bearing.
  • the present inventors performed a quenching treatment and a tempering treatment similar to those of the conventional rolling bearing manufacturing method on a test piece made of JIS standard SUJ2 having the same component composition as the above-described test piece in this example, A plurality of samples of comparative examples were produced.
  • the conditions for the quenching treatment and the tempering treatment for the sample of the comparative example were such that the hardness after the tempering treatment was about 60 HRC and the amount of retained austenite was about 4%.
  • the quenching temperature was 855 ° C., and the holding time was 30 minutes or more and 55 or less.
  • each composition ratio of R gas carbon monoxide (CO), hydrogen (H 2 ), nitrogen (N 2 ), carbon dioxide (CO 2 ) is about 20%, about 30%, about 50%, Less than about 1%).
  • the test piece was immersed in cold oil having an oil temperature of 60 ° C. or higher and 100 ° C. or lower and quenched and cooled.
  • the tempering temperature was 230 ° C., and the holding time was 2 hours or more and 3 hours or less.
  • the tempering process was performed in the R gas atmosphere.
  • the minimum value of the hardness of the comparative example sample thus obtained was 60 HRC, and the maximum value of the retained austenite amount of the comparative example sample was 4.1%.
  • the rolling bearing manufacturing method according to the present embodiment has a higher tempering temperature T 3 and a shorter holding time t compared to the conventional bearing component manufacturing method. It was confirmed that a rolling bearing having material properties equivalent to or better than conventional bearing parts can be obtained by tempering in 2 .
  • Example 4 the prediction accuracy of the second prediction formula and the third prediction formula was evaluated. Specifically, the hardness and the amount of retained austenite of the sample subjected to the tempering treatment under the tempering treatment conditions satisfying the equation (2), and the second prediction equation and the third The hardness and the amount of retained austenite predicted from the prediction formula were compared.
  • Example 3 a test piece composed of JIS standard SUJ2 and having the component composition shown in Table 1 was prepared.
  • the test piece was subjected to the same quenching treatment as in Example 3.
  • the quenching temperature T 1 was 950 ° C., and the holding time t 1 was 15 seconds.
  • the test piece was immersed in cold oil having an oil temperature of 70 ° C. and quenched and cooled.
  • the temperature T 2 was about 100 ° C.
  • the hardness of the test piece after the quenching treatment was 64.5 HRC, and the amount of retained austenite of the test piece was 14.7%.
  • Table 6 shows four tempering treatment conditions.
  • the samples 43 to 46 subjected to the tempering treatment were measured for Vickers hardness using a Vickers hardness tester and converted to Rockwell hardness. Further, the amount of retained austenite was measured for the samples 43 to 46 subjected to the tempering treatment using an X-ray diffractometer.
  • Table 6 shows the measured values of the Rockwell hardness and residual austenite amount of samples 43 to 46, and the Rockwell hardness calculated by the first prediction formula and the second prediction formula under each tempering treatment condition. Table 6 shows the predicted value of the amount of retained austenite.
  • the measured values of the Rockwell hardness of the samples 43 to 46 are the Rockwell hardness predicted from the second prediction formula and the third prediction formula when the conditions are satisfied. It was confirmed that it was in good agreement with each predicted value. Regarding Rockwell hardness, the difference between the measured value and the predicted value with respect to the predicted value was 3% or less. Further, it was confirmed that the measured values of Rockwell hardness of Samples 43 to 46 were 59 HRC or more.
  • the measured values of the retained austenite amounts of the samples 43 to 46 are the respective values of the retained austenite amounts predicted from the second prediction formula and the third prediction formula when the conditions are satisfied. It was confirmed that it was in good agreement with the predicted value. In addition, it was confirmed that each measured value of the retained austenite amount of Samples 43 to 46 was 4% or less.
  • each sample according to Example 4 obtained by performing the tempering process under the tempering process conditions satisfying the above formula (2) has a hardness equal to or higher than that of the above comparative example, and the above comparison. It was confirmed that the amount of retained austenite was equal to or less than that of the example.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Articles (AREA)
  • Rolling Contact Bearings (AREA)

Abstract

L'invention concerne un procédé de fabrication d'un élément de palier qui permet de réduire le temps requis pour réaliser un traitement de revenu par comparaison avec les procédés de fabrication classiques d'éléments de palier dans lesquels le traitement de revenu est effectué pendant une longue période et, en outre, qui présente des caractéristiques de matériau supérieures ou égales à celles des éléments de palier obtenus par les procédés classiques de fabrication d'éléments de palier. Le procédé comprend : une étape consistant à préparer un matériau cible pour former l'élément de palier formé à partir d'un acier à roulement à haute teneur en carbone ; une étape consistant à effectuer un traitement de trempe sur le matériau cible ; et une étape consistant à effectuer un traitement de revenu sur le matériau cible par chauffage du matériau cible après l'étape de traitement de trempe. À l'étape consistant de traitement de trempe, un traitement de trempe est effectué de telle sorte que la dureté du matériau cible atteint 64 à 66 HRC. À l'étape de traitement de revenu, la température de revenu T (unités : K) et le temps de maintien t (unités : secondes) satisfont une formule prescrite.
PCT/JP2018/006574 2017-02-24 2018-02-22 Procédé de fabrication d'élément de palier Ceased WO2018155588A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP2017-033670 2017-02-24
JP2017-033677 2017-02-24
JP2017033677A JP2018138686A (ja) 2017-02-24 2017-02-24 軸受部品の製造方法
JP2017033670A JP2018138685A (ja) 2017-02-24 2017-02-24 軸受部品の製造方法

Publications (1)

Publication Number Publication Date
WO2018155588A1 true WO2018155588A1 (fr) 2018-08-30

Family

ID=63253822

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2018/006574 Ceased WO2018155588A1 (fr) 2017-02-24 2018-02-22 Procédé de fabrication d'élément de palier

Country Status (1)

Country Link
WO (1) WO2018155588A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111649071A (zh) * 2020-06-12 2020-09-11 河北鑫泰轴承锻造有限公司 一种轴承外圈加工工艺
CN113699343A (zh) * 2021-07-30 2021-11-26 江苏华程工业制管股份有限公司 一种用于轴承钢管的热处理方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007239044A (ja) * 2006-03-09 2007-09-20 Ntn Corp 高周波熱処理設備
JP2008248349A (ja) * 2007-03-30 2008-10-16 Nsk Ltd 転がり軸受構成部材の製造方法および転がり軸受
JP2011144448A (ja) * 2009-08-10 2011-07-28 Jtekt Corp 転がり摺動部材の製造方法
WO2016190320A1 (fr) * 2015-05-25 2016-12-01 Ntn株式会社 Dispositif de traitement thermique et procédé de traitement thermique
JP2017008400A (ja) * 2015-06-25 2017-01-12 Ntn株式会社 軸受部品の製造方法

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007239044A (ja) * 2006-03-09 2007-09-20 Ntn Corp 高周波熱処理設備
JP2008248349A (ja) * 2007-03-30 2008-10-16 Nsk Ltd 転がり軸受構成部材の製造方法および転がり軸受
JP2011144448A (ja) * 2009-08-10 2011-07-28 Jtekt Corp 転がり摺動部材の製造方法
WO2016190320A1 (fr) * 2015-05-25 2016-12-01 Ntn株式会社 Dispositif de traitement thermique et procédé de traitement thermique
JP2017008400A (ja) * 2015-06-25 2017-01-12 Ntn株式会社 軸受部品の製造方法

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111649071A (zh) * 2020-06-12 2020-09-11 河北鑫泰轴承锻造有限公司 一种轴承外圈加工工艺
CN113699343A (zh) * 2021-07-30 2021-11-26 江苏华程工业制管股份有限公司 一种用于轴承钢管的热处理方法
CN113699343B (zh) * 2021-07-30 2022-09-09 江苏华程工业制管股份有限公司 一种用于轴承钢管的热处理方法

Similar Documents

Publication Publication Date Title
US20120247619A1 (en) Carburized steel and its process of manufacture
WO2014192117A1 (fr) Composant d'acier trempé par induction à nitruration modérée
JP2011256456A (ja) 冷間鍛造用鋼の製造方法
Johnson et al. Mechanical properties of heat-treated medium carbon steel in renewable and biodegradable oil
Giordani et al. Mechanical and metallurgical evaluation of carburized, conventionally and intensively quenched steels
Závodská et al. Fatigue resistance of low alloy steel after shot peening
JP6314648B2 (ja) 表面硬化処理部品及び表面硬化処理部品の製造方法
JP4632931B2 (ja) 冷間加工性に優れる高周波焼入れ用鋼及びその製造方法
CN104685073B (zh) 用于热处理钢构件的方法及钢构件
WO2018155588A1 (fr) Procédé de fabrication d'élément de palier
JP2009299181A (ja) 耐遅れ破壊特性に優れた高強度鋼材、高強度ボルト及びその製造方法
JP2021110032A (ja) 転がり軸受の軌道輪の製造方法
JP5754077B2 (ja) 転動疲労特性に優れた軸受鋼の製造方法および軸受鋼
JP2018138685A (ja) 軸受部品の製造方法
JP5202040B2 (ja) 耐摩耗性に優れた軸受用鋼材
JP2015030899A (ja) 軸受用鋼
JP2015030900A (ja) 軸受及び転がり軸受並びにこれらの製造方法
US11781596B2 (en) Bearing component and method for manufacturing the same
JP7063070B2 (ja) 浸炭部品
Mossaab et al. Effect of medium carbon steel microstructure on tensile strength and fatigue crack growth
JP5642327B2 (ja) 鋼材の焼入れ方法
JPH04362123A (ja) 軸受用鋼素材の製造方法
Senatorski et al. Wear resistance characteristics of thermo-chemically treated structural steels
Goncalves et al. Influence of cryogenic treatment on the fracture toughness of conventional and super clean spring steels
Lipshaw et al. A Review of Austempering for Bearing Applications

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: 18758332

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 18758332

Country of ref document: EP

Kind code of ref document: A1