Heat treatment process of alloy spring steel

A spring steel and alloy technology, applied in the field of heat treatment, can solve the problems of easy occurrence of micro-cracks, reduce the surface hardness of spring steel billets, stress concentration, etc., and achieve the effects of good comprehensive mechanical properties, reduction of quenching stress, and reduction of deformation.

Inactive Publication Date: 2020-08-28
江苏联峰实业有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to provide a heat treatment process for alloy spring steel, which is used to reduce the surface hardness of spring steel slabs, improve the local stress concentration on the surface and the problems of micro-cracks, and improve the fatigue strength and service life of spring steel

Method used

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  • Heat treatment process of alloy spring steel

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Effect test

Embodiment 1

[0029] The invention provides a heat treatment process for alloy spring steel, which includes preheating, heating, isothermal spheroidizing annealing, quenching, cooling, medium temperature tempering, two shot peening treatments and processing inspection for a billet, specifically including the following steps:

[0030] (1) The alloy spring steel billet used in the preheating section is 50CrVA or other steel billets containing Cr and V.

[0031] (2) The temperature in the preheating section is controlled at 670°C and kept for 20 minutes;

[0032] (3) Heating the steel slab to 800°C in a tube furnace or resistance furnace and keeping it warm for 30 minutes. Nitrogen gas is introduced during the process. The flow rate of nitrogen gas is 4L / h to reduce the decarburization of the steel surface and ensure the service life of the steel;

[0033] (4) cooling the billet to 650°C at a cooling rate of 100°C / h, and then performing isothermal spheroidizing annealing at 650°C for 2.5 hours...

Embodiment 2

[0040] The invention provides a heat treatment process for alloy spring steel, which includes preheating, heating, isothermal spheroidizing annealing, quenching, cooling, medium temperature tempering, two shot peening treatments and processing inspection for a billet, specifically including the following steps:

[0041] (1) The alloy spring steel billet used in the preheating section is 50CrVA or other steel billets containing Cr and V.

[0042] (2) The temperature in the preheating section is controlled at 700°C and kept for 30 minutes;

[0043] (3) Heating the steel slab to 800°C in a tube furnace or resistance furnace and keeping it warm for 60 minutes. Nitrogen gas is introduced during the process. The flow rate of nitrogen gas is 4.5L / h to reduce the decarburization of the steel surface and ensure the service life of the steel;

[0044] (4) cooling the billet to 680°C at a cooling rate of 110°C / h, and then performing isothermal spheroidizing annealing at 680°C for 2 hours...

Embodiment 3

[0051] The invention provides a heat treatment process for alloy spring steel, which includes preheating, heating, isothermal spheroidizing annealing, quenching, cooling, medium temperature tempering, two shot peening treatments and processing inspection for a billet, specifically including the following steps:

[0052] (1) The alloy spring steel billet used in the preheating section is 50CrVA or other steel billets containing Cr and V.

[0053] (2) The temperature in the preheating section is controlled at 750°C and kept for 40 minutes;

[0054] (3) Heating the steel slab to 840°C in a tube furnace or resistance furnace and keeping it warm for 50 minutes. Nitrogen gas is introduced during the process. The flow rate of nitrogen gas is 5 / h to reduce the decarburization of the steel surface and ensure the service life of the steel;

[0055] (4) cooling the billet to 700°C at a cooling rate of 120°C / h, and then performing isothermal spheroidizing annealing at 700°C for 2 hours;

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Abstract

The invention provides a heat treatment process of alloy spring steel. The process comprises the steps of performing preheating, heating, isothermal spheroidizing annealing, quenching, cooling, medium-temperature tempering, two times of shot blasting treatment and processing inspecting on a steel billet. According to the method, the temperature of isothermal spheroidizing annealing is controlled to be 650-700 DEG C, and the annealing time is 2-3 hours, so that the phenomenon that part of carbide cannot be fully spheroidized is avoided, the hardness of the spring steel is reduced to 32-48 HRC,the problem that deforming or cracking is prone to occur in subsequent heat treatment is solved, the corresponding tensile strength is reduced to 1810-1930 MPa, the using stress amplitude is improvedby 10 %-15 % compared with that of spring steel prepared through a traditional technology, and the novel spring steel has higher ductility and toughness; the quenching temperature is controlled to reduce the quenching stress and reduce the deformation, so that a high yield ratio and good comprehensive mechanical properties are obtained; and the cooling mode is controlled, and the two times of shotblasting treatment is adopted, so that the surface of the spring steel is strengthened, the surface quality of the spring steel is improved, the residual compressive stress is generated on the surface, and the the spring steel is improved in fatigue strength and prolonged in service life.

Description

technical field [0001] The invention relates to the technical field of heat treatment, in particular to a heat treatment process of alloy spring steel. Background technique [0002] Spring steel is widely used in modern industrial equipment, mechanical parts, automobiles, engines, railways and other industries. The spring mainly works under dynamic load, that is, under the condition of shock and vibration, or under the action of alternating stress, and uses elastic deformation to absorb impact energy and act as a buffer. Since the spring is often subjected to vibration and long-term work under the action of phase change stress, mainly due to fatigue damage, the spring steel must have a high elastic limit and a high fatigue limit. In addition, there should be enough toughness and plasticity to prevent sudden brittle fracture under impact force. With the enhancement of my country's industrial capacity, industrial equipment is developing in the direction of large load and hig...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D9/02C21D1/18C21D1/32C21D6/00C21D7/06
CPCC21D1/18C21D1/32C21D6/00C21D7/06C21D9/02
Inventor 赵小军谷杰黄飞
Owner 江苏联峰实业有限公司
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