Forging heating method of W9Cr4V2Mo steel for bearing ring

Abstract

The invention discloses a forging heating method for W9Cr4V2Mo steel for a bearing ring, and relates to the field of bearing part forging. The problems that existing W9Cr4V2Mo steel for bearings is long in forging heating time, large in deformation resistance and prone to cracking during deformation are solved. The method comprises preheating; opening the furnace for cooling, and loading a bar material; and closing the furnace, heating and preserving heat. According to the method, the high-temperature heat preservation temperature is controlled to be 1170 DEG C, the heat penetration coefficient is controlled to be 0.25, the heating temperature is increased, the heat preservation time is shortened, heat preservation structures are heated thoroughly, and meanwhile the production heating efficiency of the raw forgings is improved. The method is used for forging and heating the W9Cr4V2Mo steel for the bearing ring.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of bearing part forging. BACKGROUND

[0002] A certain type of bearing ring in China adopts W9Cr4V2Mo steel which is similar to Russian system material. The material belongs to ledeburite tool steel, and contains a large amount of alloy elements such as W, Cr and Mo. The eutectic primary carbide in the steel is in the form of fishbone, and the carbide is unevenly distributed. Therefore, it is necessary to deform the material by forging to fully break and disperse the primary carbide. In addition, due to the high carbon and high alloy, the plasticity is low and the deformation resistance is large, which leads to the fact that cracks are easily generated in the forging process. The conventional ledeburite tool steel needs to be preheated for a long time before the forging process to reduce the deformation resistance of the material and realize the forging forming.

[0003] Therefore, it is necessary to find a reasonable forging heating process to shorten the forging heating time, reduce the deformation resistance of the steel in the forging deformation process, improve the plasticity, and solve the problem that both large deformation and crack-free deformation of the forged piece are required in the forging process. SUMMARY

[0004] The present application solves the problems of long forging heating time, large deformation resistance and easy deformation cracking of W9Cr4V2Mo steel for bearings, and provides a forging heating process method of W9Cr4V2Mo steel for aviation bearing rings.

[0005] A forging heating method of W9Cr4V2Mo steel for bearing rings, which is specifically performed according to the following steps:

[0006] I. Heat the high-temperature box-type resistance furnace to 1160-1180℃ and keep it for 4-4.5h;

[0007] II. Open the furnace door of the high-temperature box-type resistance furnace after step I, and cool it to 895-905℃, then put the bar into the resistance furnace, and close the furnace door and heat it with the furnace;

[0008] III. After the temperature of the resistance furnace in step II is raised to 1160-1180℃, keep it for a certain time, and the time t=Φ×0.25, wherein Φ is the diameter of the bar, and the unit is mm; t is in min;

[0009] IV. After the keeping time in step III is over, take out the treated bar and forge it to obtain a forged piece.

[0010] Further, the material of the bar in step II is W9Cr4V2Mo steel.

[0011] Further, the average grain size of the forged piece obtained in step IV is ≥7 levels.

[0012] Further, the rod diameter Φ in step three is 20-150 mm.

[0013] The present application has the following advantages:

[0014] The present application increases the high-temperature box-type resistance furnace heating to the set temperature, lifts the furnace door to reduce the temperature, then loads the material to increase the temperature, and the temperature of the furnace is increased from 900 DEG C to 1170 DEG C, which replaces the long-time afterheat holding time.

[0015] The total forging heating time is reduced compared with the conventional process, the forging grain is not coarse, overheating and overburning, the grain size is 7, and the average grain size meets the standard requirement of being greater than or equal to 7.

[0016] The present application is used for W9Cr4V2Mo steel forging heating of bearing ring. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 The forging process curve is described for the example;

[0018] Figure 2 The conventional forging process curve is described for the comparative example;

[0019] Figure 3 The grain size detection diagram of the forging obtained for the example is shown. DETAILED DESCRIPTION

[0020] Specific embodiment one: a W9Cr4V2Mo steel forging heating method for bearing ring, which is specifically performed according to the following steps:

[0021] I. The high-temperature box-type resistance furnace is heated to 1160-1180 DEG C, and the holding time is 4-4.5 h;

[0022] II. The furnace door of the high-temperature box-type resistance furnace after step I is opened, the temperature is reduced to 895-905 DEG C, then the rod material is loaded into the resistance furnace, and the furnace door is closed to increase the temperature;

[0023] III. After the temperature of the resistance furnace in step II is increased to 1160-1180 DEG C, the holding time t=Φ×0.25, wherein Φ is the rod diameter, and the unit is mm; t is min;

[0024] IV. After the holding time in step III is finished, the treated rod material is taken out, and is forged to obtain the forging.

[0025] Specific implementation two: the difference between this embodiment and specific implementation one is that: step two opens the high temperature box type resistance furnace door by 1 / 4. The others are the same as specific implementation one.

[0026] Specific implementation three: the difference between this embodiment and specific implementation one or two is that: the material of the rod in step two is W9Cr4V2Mo steel. The others are the same as specific implementation one or two.

[0027] Specific implementation four: the difference between this embodiment and one of specific implementation one to three is that: the temperature is reduced to 900 DEG C in step two. The others are the same as specific implementation one to three.

[0028] Specific implementation five: the difference between this embodiment and one of specific implementation one to four is that: the high temperature box type resistance furnace is heated to 1170 DEG C in step one, and the temperature is kept for 4h. The others are the same as specific implementation one to four.

[0029] Specific implementation six: the difference between this embodiment and one of specific implementation one to five is that: the temperature of the resistance furnace is returned to 1170 DEG C in step three, and then the temperature is kept. The others are the same as specific implementation one to five.

[0030] Specific implementation seven: the difference between this embodiment and one of specific implementation one to six is that: the diameter of the rod in step three is 20-150mm. The others are the same as specific implementation one to six.

[0031] Specific implementation eight: the difference between this embodiment and one of specific implementation one to seven is that: after step four is completed, the subsequent rod repeats steps two-four. The others are the same as specific implementation one to seven.

[0032] Specific implementation nine: the difference between this embodiment and one of specific implementation one to eight is that: the average grain size of the forged piece obtained in step four is greater than or equal to 7. The others are the same as specific implementation one to eight.

[0033] Specific implementation ten: the difference between this embodiment and one of specific implementation one to nine is that: the forged piece obtained in step four is kept at a temperature of 1160-1180 DEG C. The others are the same as specific implementation one to nine.

[0034] The content of the application is not limited to the content of the above embodiments, and one or more specific embodiments can also achieve the purpose of the application.

[0035] Example:

[0036] A W9Cr4V2Mo steel forging heating method for bearing ring, specifically according to the following steps:

[0037] I. The high-temperature box-type resistance furnace is heated to 1170℃ and kept for 4h;

[0038] II. The furnace door of the high-temperature box-type resistance furnace after step I is opened by 1 / 4 and cooled to 900℃, then a certain type of bearing ring forging is loaded into the resistance furnace with a bar material, the bar material is W9Cr4V2Mo steel, the bar diameter is Φ100mm, the bar length is 172.1mm, and the furnace door is closed and the furnace is heated;

[0039] III. After the temperature of the resistance furnace in step II is returned to 1170℃, the temperature is kept for 25min;

[0040] IV. After the temperature keeping in step III is finished, the treated bar is taken out and forged to obtain a forging;

[0041] V. After step IV is completed, the subsequent bar repeats steps II-IV.

[0042] Comparative Example:

[0043] The conventional forging process is used in the comparative example:

[0044] I. The medium-temperature box-type resistance furnace is heated to 800℃ and the high-temperature box-type resistance furnace is heated to 1140℃;

[0045] II. The bar is loaded into the medium-temperature box-type resistance furnace, the bar material is W9Cr4V2Mo steel, the bar diameter is Φ100mm, and the bar length is 172.1mm. After the temperature is restored to 800℃, the temperature is kept for 100min;

[0046] III. After the temperature keeping is finished, the bar is transferred to the high-temperature box-type resistance furnace. After the temperature is restored to 1140℃, the temperature is kept for 80min;

[0047] IV. The temperature keeping is finished and the bar is forged;

[0048] V. After the forging is formed, the subsequent product repeats steps II-IV.

[0049] Figure 1 The forging process curve for the example;

[0050] Figure 2 The conventional forging process curve for the comparative example;

[0051] Figure 3 The grain size detection diagram of the forging obtained in the example.

[0052] Compared with the conventional process, the total forging heating time is reduced, the forging piece does not have problems such as forging piece grain coarsening, overheating and overburning due to temperature increase, the grain size is 7 levels, and the requirement that the average grain size is greater than or equal to 7 levels is met.

[0053] The application increases high-temperature box-type resistance air furnace heating to the set temperature, lifts the furnace door to cool down, then loads the material to heat up with the furnace, and the process of heating up from 900 DEG C to 1170 DEG C with the furnace instead of the long-time afterheat holding time. The high-temperature holding temperature is 1170 DEG C, the thermal penetration coefficient is 0.25, the heating temperature is increased, the holding time is reduced, the holding organization is penetrated, and the heating efficiency of the green forging piece production is improved.

Claims

1. A heating method for forging W9Cr4V2Mo steel bearing rings, characterized in that... This method is specifically carried out in the following steps:

1. Heat the high-temperature box-type resistance furnace to 1160~1180℃ and hold for 4~4.5 hours; 2. Open the furnace door of the high-temperature box-type resistance furnace after heating in step one, cool it down to 895~905℃, then load the bar stock into the resistance furnace, close the furnace door and heat up with the furnace.

3. After the resistance furnace temperature in step 2 returns to 1160~1180℃, it is kept at that temperature for a period of t=Φ×0.25, where Φ is the diameter of the bar stock in mm and t is in min. Fourth, after the heat preservation in step three is completed, the processed bar stock is taken out and forged to obtain a forging.

2. The forging heating method for W9Cr4V2Mo steel bearing rings according to claim 1, characterized in that... Step 2: Open the furnace door of the high-temperature box-type resistance furnace by 1 / 4.

3. The forging heating method for W9Cr4V2Mo steel bearing rings according to claim 1, characterized in that... The material of the material segment mentioned in step two is W9Cr4V2Mo steel.

4. The forging heating method for W9Cr4V2Mo steel bearing rings according to claim 1, characterized in that... Step two: Cool down to 900℃.

5. The forging heating method for W9Cr4V2Mo steel bearing rings according to claim 1, characterized in that... Step 1: Heat the high-temperature box-type resistance furnace to 1170℃ and hold for 4 hours.

6. The forging heating method for W9Cr4V2Mo steel bearing rings according to claim 1, characterized in that... Step 3: After the resistance furnace temperature returns to 1170℃, it is kept at that temperature.

7. The forging heating method for W9Cr4V2Mo steel bearing rings according to claim 1, characterized in that... The value range of the bar diameter Φ in step three is 20~150mm.

8. The forging heating method for W9Cr4V2Mo steel bearing rings according to claim 1, characterized in that... After step four is completed, subsequent bars will repeat steps two through four.

9. The forging heating method for W9Cr4V2Mo steel bearing rings according to claim 1, characterized in that... Step four: Obtain an average grain size of ≥7 for the forging.

10. The forging heating method for W9Cr4V2Mo steel bearing rings according to claim 1, characterized in that... Step four involves holding the forging at a temperature of 1160~1180℃ after obtaining it.

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