CN103898283A

CN103898283A - Tempering heat treatment process of high-strength steel

Info

Publication number: CN103898283A
Application number: CN201410111973.2A
Authority: CN
Inventors: 杨爱宁; 曹鹏; 唐钟雪; 胡进林; 张宏凯; 马进
Original assignee: Kocel Group Co Ltd
Current assignee: Kocel Steel Foundry Co Ltd; Kocel Group Co Ltd
Priority date: 2014-03-25
Filing date: 2014-03-25
Publication date: 2014-07-02
Anticipated expiration: 2034-03-25
Also published as: CN103898283B

Abstract

The invention relates to a tempering heat treatment process and in particular relates to a tempering heat treatment process of high-strength steel. The process comprises the following steps: heating a material to 850-920 DEG C to be austenitized and furnace-cooling the material to the room temperature to be annealed after insulating the material for 3-5 hours to achieve the aim of tissue homogenization; heating the material to 850-920 DEG C to be austenitized and water-quenching the material to 200-260 DEG C after insulating the material for 3-5 hours; carrying out high-temperature tempering after insulating the quenched material for 2-5 hours at 590 DEG C, 610 DEG C, 630 DEG C, 650 DEG C and 670 DEG C respectively. The process has the effects that the method is unique; by controlling and adjusting the tempering and insulating temperatures, the impacts of the tempering heat treatment process on the low-temperature impact property of the high-strength steel are determined, the best tempering process parameters including the material strength and tenacity up to the standard are obtained and the comprehensive properties of the material used in the low-temperature environments are ensured to meet the requirements.

Description

A kind of tempering heat treatment process of high-strength steel

Technical field

The present invention relates to a kind of tempering heat treatment process, especially relate to a kind of tempering heat treatment process of high-strength steel.

Background technology

General high-strength cast steel material, intensity is high, poor toughness, and especially, under the low working conditions of temperature, material fragility fracture tendency can increase, and the balance that now maintains intensity and toughness has larger difficulty.At present, in heat treatment process, the repeatability of the low-temperature impact toughness of material and reproducibility are very poor.In the process that produce early stage, often there is the situation that intensity and impact property can not be simultaneously satisfied, in the time that intensity can meet the demands, low-temperature impact does not reach the index of performance requriements, or low-temperature impact is when can meeting the demands, intensity is lower than the requirement of performance index, and material-20 ℃ impact and-40 ℃ of impact results are unstable, greatly extend the cycle of testing, increased the cost of manufacturing, restricted the development of enterprise simultaneously.

Also do not overcome so far aforesaid method.

Summary of the invention

The object of the invention is to overcome the defect of prior art, a kind of method uniqueness is provided, passes through regulating and controlling tempering holding temperature, determine the impact of tempering heat treatment process on high-strength steel low temperature impact properties, obtain all standard compliant best tempering process parameters of the strength of materials and toughness, the tempering heat treatment process of the satisfactory a kind of high-strength steel of over-all properties that assurance material uses under low temperature environment.

The present invention realizes in the following way:

A tempering heat treatment process for high-strength steel, is characterized in that: this technique comprises the steps:

A, material is heated to 850 ℃～920 ℃ austenitizings, is incubated after 3～5 hours, be chilled to annealing at room temperature with stove, reach the object of microstructure homogenization;

B, material is heated to 850 ℃～920 ℃ austenitizings, is incubated after 3～5 hours shrend to 200 ℃～260 ℃;

C, the material after quenching is carried out to high tempering after being incubated 2～5 hours respectively at 590 ℃, 610 ℃, 630 ℃, 650 ℃, 670 ℃;

The chemical composition of described material is C%:0.25-0.32, Si%:0.60-0.90, Mn%:0.90-1.10, P%≤0.04, S%≤0.045, Cr%:0.40-0.80, Mo%:0.15-0.35, Ni%:0.4-0.8;

The phase point temperature of described material, AC3 is 841 ℃, AC1 is 726 ℃;

The best tempering parameter that described material meets over-all properties is 650 ℃ of insulations 2～3 hours.

The present invention has following effect:

1) method uniqueness: method provided by the invention is heat-treated determining of process system according to industry standard and standard, the chemical composition of foundry goods is C%:0.25-0.32, Si%:0.60-0.90, Mn%:0.90-1.10, P%≤0.04, S%≤0.045, Cr%:0.40-0.80, Mo%:0.15-0.35, Ni%:0.4-0.8, determine rational heat treatment process parameter: first determine the phase point temperature of this material, AC ₃be 841 ℃, AC ₁be 726 ℃, then determine that system of heat treatment process is " annealing+quenching water-cooled+high tempering air cooling ".The main purpose of annealing is the microstructure homogenization that reaches material, then adopt quenching water-cooled to make the structure refinement of material, improve the comprehensive mechanical property of material simultaneously, finally make matrix recrystallize and the alligatoring of carbide particle, nodularization by high tempering, because the nodularization of carbide reduces the distance of dislocation glide, the distance of slippage is shortened, thereby plasticity, toughness are in rising trend.

2) obtain the results of property shown in table 1 and Fig. 1 by above-mentioned thermal treatment process, can determine according to result, this material is with the raising of tempering temperature, the intensity trend that tapers off, low temperature impact properties first raises and reduces afterwards, when tempering temperature is 650 ℃, intensity and low temperature impact properties all can meet performance requriements, but in the time that tempering temperature is 670 ℃, low temperature impact properties declines and intensity can not meet performance requriements.Therefore, this material can meet the best tempering parameter of over-all properties be 650 ℃ insulation 2～3 hours.

The results of property of material under the different tempering temperatures of table 1

3) obtain all standard compliant best tempering process parameters of the strength of materials and toughness, guarantee that the over-all properties that material uses under low temperature environment meets: guaranteed good room temperature comprehensive mechanical property and higher low-temperature impact toughness, met the over-all properties that material uses under low temperature environment: tensile strength >=725MPa, yield strength >=585MPa, unit elongation >=17%, relative reduction in area >=35% ,-20 ℃ of AKv >=42J ,-40 ℃ of AKv >=27J; In guaranteeing the low temperature impact properties of material under different tempering temperature conditions, obtain optimum tempering property parameter, make this material can meet high strength and high low temperature impact properties requirement simultaneously, the definite of system of heat treatment process and raising product specification are had very important significance.

Accompanying drawing explanation

The results of property of material under the different tempering temperatures of Fig. 1

Embodiment

A tempering heat treatment process for high-strength steel, this technique comprises the steps: a, material is heated to 850 ℃～920 ℃ austenitizings, is incubated after 3～5 hours, is chilled to annealing at room temperature with stove, reaches the object of microstructure homogenization; B, material is heated to 850 ℃～920 ℃ austenitizings, is incubated after 3～5 hours shrend to 200 ℃～260 ℃; C, the material after quenching is carried out to high tempering after being incubated 2～5 hours respectively at 590 ℃, 610 ℃, 630 ℃, 650 ℃, 670 ℃.Present method realizes high strength and the low temperature impact properties requirement of material by " annealing+quenching water-cooled+high tempering air cooling ".The chemical composition of described material is C%:0.25-0.32, Si%:0.60-0.90, Mn%:0.90-1.10, P%≤0.04, S%≤0.045, Cr%:0.40-0.80, Mo%:0.15-0.35, Ni%:0.4-0.8.The phase point temperature of described material, AC3 is 841 ℃, AC1 is 726 ℃.The best tempering parameter that described material meets over-all properties is 650 ℃ of insulations 2～3 hours.

Claims

1. a tempering heat treatment process for high-strength steel, is characterized in that: this technique comprises the steps:

A, material is heated to 850 ℃ ~ 920 ℃ austenitizings, is incubated after 3 ~ 5 hours, be chilled to annealing at room temperature with stove, reach the object of microstructure homogenization;

B, material is heated to 850 ℃ ~ 920 ℃ austenitizings, is incubated after 3 ~ 5 hours shrend to 200 ℃ ~ 260 ℃;

C, the material after quenching is carried out to high tempering after being incubated 2 ~ 5 hours respectively at 590 ℃, 610 ℃, 630 ℃, 650 ℃, 670 ℃.

2. the tempering heat treatment process of a kind of high-strength steel as claimed in claim 1, is characterized in that: the chemical composition of described material is C%:0.25-0.32, Si%:0.60-0.90, Mn%:0.90-1.10, P%≤0.04, S%≤0.045, Cr%:0.40-0.80, Mo%:0.15-0.35, Ni%:0.4-0.8.

3. the tempering heat treatment process of a kind of high-strength steel as claimed in claim 1, is characterized in that the phase point temperature of described material, and AC3 is 841 ℃, and AC1 is 726 ℃.

4. the tempering heat treatment process of a kind of high-strength steel as claimed in claim 1, is characterized in that: the best tempering parameter that described material meets over-all properties is 650 ℃ of insulations 2 ~ 3 hours.