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Heat treatment technology for grey cast iron HT250 bearing ring

A technology for bearing rings and gray cast iron, which is applied in the field of heat treatment of gray cast iron HT250 bearing rings, can solve the problems of reduced fatigue strength of rings, affecting the service life of bearings, and large dispersion of hardness values. uncomplicated effects

Inactive Publication Date: 2015-11-04
C&U CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] After heat treatment, the large difference in hardness value ≥ 3HRC will lead to a decrease in the fatigue strength of the ring, which will seriously affect the service life of the bearing. In addition, the large difference in hardness will cause the bearing ring to break, and the fracture rate accounts for at least 10%.

Method used

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  • Heat treatment technology for grey cast iron HT250 bearing ring
  • Heat treatment technology for grey cast iron HT250 bearing ring
  • Heat treatment technology for grey cast iron HT250 bearing ring

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] The heat treatment process includes the following steps:

[0022] (1) Quenching: Adjust the quenching temperature to 890°C and keep it warm for 50 minutes. The holding time is determined according to the wall thickness of the gray cast iron HT250 bearing ring and the amount of furnace for heat treatment, then oil cooling, and the oil temperature is set to 100°C. Then cool to room temperature;

[0023] (2) Step tempering, heat up the gray cast iron HT250 bearing ring to 180°C, keep it warm for 2 hours, then continue to raise the temperature of the gray cast iron HT250 bearing ring to 300°C, keep it warm for 2 hours, and then air cool to room temperature.

[0024] The gray cast iron HT250 bearing ring in this embodiment includes the following components, in mass percentage:

[0025] C 3.0~3.6%; Si 2.0~2.6%; Mn 0.6~1.0%; Cr 0.5~1.0%;

[0026] P below 0.1%; S below 0.1%; the balance is Fe.

Embodiment 2

[0028] The heat treatment process includes the following steps:

[0029] (1) Quenching: Adjust the quenching temperature to 920°C and keep it warm for 60 minutes. The holding time is determined according to the wall thickness of the gray cast iron HT250 bearing ring and the amount of heat treatment furnace, then oil cooling, the oil temperature is set to 110°C, and then Cool to room temperature;

[0030] (2) Step tempering, heat up the gray cast iron HT250 bearing ring to 190°C, keep it warm for 4 hours, then continue to heat up the gray cast iron HT250 bearing ring to 310°C, keep it warm for 4 hours, and then air cool to room temperature.

[0031] The gray cast iron HT250 bearing ring in this embodiment includes the following components, in mass percentage:

[0032] C 3.0~3.6%; Si 2.0~2.6%; Mn 0.6~1.0%; Cr 0.5~1.0%;

[0033] P below 0.1%; S below 0.1%; the balance is Fe.

Embodiment 3

[0035] The heat treatment process includes the following steps:

[0036] (1) Quenching: Adjust the quenching temperature to 900°C and keep it warm for 55 minutes. The holding time is determined according to the wall thickness of the gray cast iron HT250 bearing ring and the amount of furnace for heat treatment, then oil cooling, the oil temperature is set to 105°C, and then Cool to room temperature;

[0037] (2) Step tempering, heat up the gray cast iron HT250 bearing ring to 185°C, keep it warm for 3 hours, then continue to raise the temperature of the gray cast iron HT250 bearing ring to 305°C, keep it warm for 3 hours, and then air cool to room temperature.

[0038] The gray cast iron HT250 bearing ring in this embodiment includes the following components, in mass percentage:

[0039] C 3.0~3.6%; Si 2.0~2.6%; Mn 0.6~1.0%; Cr 0.5~1.0%;

[0040] P below 0.1%; S below 0.1%; the balance is Fe.

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Abstract

The invention discloses a heat treatment technology for a grey cast iron HT250 bearing ring. The heat treatment technology is characterized by including the following procedures that firstly, quenching is performed, wherein quenching temperature is adjusted to 890-920 DEG C, the temperature is kept for 50-60 min, then oil cooling is performed, oil temperature is set to be 100+ / -10 DEG C, and the oil temperature is lowered to room temperature in a cooling manner; and secondly, step type tempering is performed, wherein the temperature of the grey cast iron HT250 bearing ring is raised to 180+ / -10 DEG C, the temperature is kept for 2-4 h, then the temperature of the grey cast iron HT250 bearing ring continues to be raised to 300+ / -10 DEG C, the temperature is kept for 2-4 h, and the temperature of the grey cast iron HT250 bearing ring is lowered to room temperature in an air cooling manner. The heat treatment technology has the beneficial effects that uniformity of the hardness value of the grey cast iron HT250 bearing ring where heat treatment is performed is remarkably improved, and the performance of the bearing ring is improved.

Description

technical field [0001] The invention relates to a heat treatment process for materials, in particular to a heat treatment process for a gray cast iron HT250 bearing ring. Background technique [0002] HT250 (GB 9439—1988) is a pearlitic type of gray cast iron, which is often used to process bearing rings. The existing gray cast iron HT250 bearing rings all need heat treatment after forming. [0003] Existing heat treatment process, quenching: adjust the quenching temperature to 850°C ~ 870°C, keep warm for 50min ~ 60min, then oil cooling, set the oil temperature to 100±10°C, and then cool to room temperature; tempering: directly use 300°C± 10°C. [0004] However, the heat treatment process of this gray cast iron HT250 bearing ring has the following defects: [0005] After heat treatment, a large dispersion of hardness value ≥ 3HRC will lead to a decrease in the fatigue strength of the ring, which will seriously affect the service life of the bearing. In addition, the larg...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D9/40C21D1/18C21D5/00C22C37/10
Inventor 张志祥郭长建
Owner C&U CO LTD
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