CN105200199A

CN105200199A - Heat treatment technology for improving properties of 60Si2Mn spring steel

Info

Publication number: CN105200199A
Application number: CN201410287791.0A
Authority: CN
Inventors: 马琳
Original assignee: Individual
Current assignee: Individual
Priority date: 2014-06-25
Filing date: 2014-06-25
Publication date: 2015-12-30

Abstract

The invention discloses a heat treatment technology for improving the properties of 60Si2Mn spring steel. The heat treatment technology is characterized by comprising the steps that the temperature of the 60Si2Mn spring steel is increased to 850 DEG C at the temperature increasing speed of 5 DEG C/s, and heat preservation is performed for 50 min; the temperature is lowered to 20 DEG C at the temperature lowering speed of 50-240 DEG C/s in a quenching medium adopting 13% PAG or 5% salt water or graded quenching oil, and heat preservation is performed for 50 min; the temperature is increased to 420 DEG C, heat preservation is performed for 50 min, and then oil cooling is performed; the temperature lowering speed is set at 120 DEG C/s, and the 13% PAG is adopted as the quenching medium.

Description

A kind of thermal treatment process improving 60Si2Mn spring steel performance

Technical field

The present invention relates to a kind of thermal treatment process improving 60Si2Mn spring steel performance.

Background technology

Spring steel refers to due to the elasticity under Quench and temper state, and is specifically designed to the steel manufacturing spring and elastic element.The elasticity of steel depends on the ability of its recoverable deformation, and namely within the scope of regulation, the ability of recoverable deformation makes it bear certain load, after load is removed, do not occur tension set.Spring steel should have excellent over-all properties, as mechanical property (particularly elastic limit, breakdown point, yield tensile ratio), elasticity attenuation resistance can (namely elastoresistance goes down performance, also known as relaxation resistance), fatigue property, hardening capacity, physical and chemical performance (heat-resisting, low temperature resistant, anti-oxidant, corrosion-resistant etc.).In order to meet above-mentioned performance requriements, spring steel has excellent metallurgical quality (high clarity and homogeneity), good surface quality (strict control surface defect and decarburization), accurate profile and size.

Summary of the invention

The technical problem to be solved in the present invention is: provide a kind of thermal treatment process improving 60Si2Mn spring steel performance, to improve the performance of this steel.

Technical scheme of the present invention is: a kind of thermal treatment process improving 60Si2Mn spring steel performance, 60Si2Mn spring steel is warming up to 850 DEG C with the temperature rise rate of 5 DEG C/s, insulation 50min, after with the rate of temperature fall of 50-240 DEG C/s again quenchant be 13%PAG, carry out being cooled to 20 DEG C in 5% salt solution or hierarchical quenching oil, insulation 50min, after be warming up to again 420 DEG C, insulation 50min, rear oil cooling.

Rate of temperature fall is 120 DEG C/s, and quenchant is 13%PAG.

Beneficial effect of the present invention: along with the decline of speed of cooling, tensile strength and the yield strength entirety of this material present downward trend, but the yield strength under middle cooling rate rises; Also be eager to excel than the bulk strength under 440 DEG C of tempering states 200 DEG C of tempering states.

With the decline of speed of cooling, downward trend after the plasticity of this material presents and first rises, the plasticity of the plasticity ratio under middle cooling rate under same state is eager to excel, and the overall plasticity under overall plasticity ratio 200 DEG C of tempering states at 440 DEG C is eager to excel.Ms point raises along with the increase of quenching velocity.The comprehensive mechanical property of the middle quenching velocity under 120 DEG C/s cooling rate and 13%PAG quenchant is best.The tissue effect of quenching velocity to 60Si2Mn spring steel is not obvious.Middle quenching velocity has stabilization to austenite, and the middle cooling rate under this possible explanation 13%PAG has the reason having good plasticity.

Accompanying drawing explanation

Fig. 1 is that different quenching velocity is strong on 60Si2Mn, the impact of plasticity;

Fig. 2 is the impact of different quenching velocity on 60Si2Mn spring steel hardness.

Embodiment

A kind of thermal treatment process improving 60Si2Mn spring steel performance, it is characterized in that: 60Si2Mn spring steel is warming up to 850 DEG C with the temperature rise rate of 5 DEG C/s, insulation 50min, after with the rate of temperature fall of 50-240 DEG C/s again quenchant be 13%PAG, carry out being cooled to 20 DEG C in 5% salt solution or hierarchical quenching oil, insulation 50min, after be warming up to again 420 DEG C, insulation 50min, rear oil cooling.Rate of temperature fall is 120 DEG C/s, and quenchant is 13%PAG.

Can find out according to Fig. 1 curve, on the whole along with the increase of quenching velocity, its tensile strength and moulding present first to reduce increase afterwards, the last trend reduced again, as can be seen from the figure, when speed of cooling is 120 DEG C/s, the tensile strength of 60Si2Mn spring steel and moulding over-all properties the best.

Plot analysis is carried out, as Fig. 2 to the mechanical property of hardness.On the whole, the increase with quenching velocity between 50 DEG C/s-120 DEG C/S presents the trend increased progressively, this is because, the increase in this interval along with speed of cooling, in spring steel, austenite increases to martensitic transformation amount; Between 120 DEG C/s-160 DEG C/s, because higher quenching velocity makes the austenite in spring steel have little time to martensitic transformation, so the increase along with quenching velocity presents the trend of successively decreasing, and then, between 160 DEG C/s-240 DEG C/s, because speed of cooling is larger, the carbide inside spring steel and impurity atoms have little time diffusion, are stored in matrix, so the increase with quenching velocity presents the trend of increase.

Along with the decline of speed of cooling, tensile strength and the yield strength entirety of this material present downward trend, but the yield strength under middle cooling rate rises; Also be eager to excel than the bulk strength under 440 DEG C of tempering states 200 DEG C of tempering states.

Claims

1. one kind is improved the thermal treatment process of 60Si2Mn spring steel performance, it is characterized in that: 60Si2Mn spring steel is warming up to 850 DEG C with the temperature rise rate of 5 DEG C/s, insulation 50min, after with the rate of temperature fall of 50-240 DEG C/s again quenchant be 13%PAG, carry out being cooled to 20 DEG C in 5% salt solution or hierarchical quenching oil, insulation 50min, after be warming up to again 420 DEG C, insulation 50min, rear oil cooling.

2. a kind of thermal treatment process improving 60Si2Mn spring steel performance according to claim 1, it is characterized in that: rate of temperature fall is 120 DEG C/s, quenchant is 13%PAG.