阅读说明：本技术 一种钢浅层渗碳的热处理方法 (Heat treatment method for superficial carburization of steel ) 是由 鞠殿巍 李立群 辛玉武 孙东文 曾西军 师玉英 张宇慧 孙振淋 辛昕 宋鸿超 于 2020-04-30 设计创作，主要内容包括：本发明涉及热处理领域,尤其是一种钢浅层渗碳的热处理方法。该方法包括：对零件的非渗碳区域镀铜防护；零件包括非渗碳区域和渗碳区域；清理渗碳区域的渗碳表面；在可控气氛炉内,对渗碳表面进行首次渗碳；其中,首次渗碳的第二段中,其碳势范围为0.75±0.05％C；首次渗碳包括两段；零件渗碳后淬火、高温回火、去铜。本发明解决了常规工艺参数存在零件渗碳层深度容易超差、零件变形严重等问题。(The invention relates to the field of heat treatment, in particular to a heat treatment method for superficial carburization of steel. The method comprises the following steps: copper plating protection is carried out on a non-carburized area of the part; the part includes a non-carburized region and a carburized region; cleaning a carburized surface of a carburized area; performing primary carburization on a carburized surface in a controlled atmosphere furnace; wherein, in the second stage of the first carburization, the carbon potential range is 0.75 +/-0.05% C; the first carburization comprises two sections; quenching, high-temperature tempering and copper removal are carried out after the parts are carburized. The method solves the problems of easy out-of-tolerance of the depth of the carburized layer of the part, serious deformation of the part and the like existing in the conventional process parameters.)

1. A heat treatment method for shallow carburization of steel is characterized by comprising the following steps:

copper plating protection is carried out on a non-carburized area of the part; the part includes a non-carburized region and a carburized region;

cleaning a carburized surface of a carburized area;

performing primary carburization on a carburized surface in a controlled atmosphere furnace; wherein, in the second stage of the first carburization, the carbon potential range is 0.75 +/-0.05% C; the first carburization comprises two sections;

quenching, high-temperature tempering and copper removal are carried out after the parts are carburized.

2. The method of claim 1, further comprising:

carrying out integral copper plating on the final part;

performing secondary carburization on the whole copper-plated part in a controlled atmosphere furnace;

and quenching, ice-cooling, tempering and inspecting the parts subjected to secondary carburization.

3. The method of claim 2, wherein the conditions for first carburization include:

the range of the heat preservation temperature is 920 +/-10 ℃; the carbon potential range of the first section is 0.35 +/-0.05 percent C, and the heat preservation time range is 35 +/-5 min; the carbon potential range of the second section is 0.75 +/-0.05% C, the heat preservation time range is 50 +/-20 min, the furnace temperature reduction range is 840 +/-20 ℃, the carbon potential range is 0.75 +/-0.05% C, and the heat preservation time range is 20 +/-10 min.

4. The method according to claim 1, wherein the first copper plating has a copper layer thickness in the range of 0.03 to 0.05 mm; the thickness range of the copper layer of the first copper plating is 0.02-0.04 mm.

5. The method of claim 3, wherein the conditions for secondary carburization are:

in a controlled atmosphere furnace, the temperature range is 910 +/-10 ℃, the carbon potential range is 0.4 +/-0.1 percent C, and the temperature range is 50 +/-20 min.

6. The method according to claim 5, characterized in that the quenching conditions are: after the heat preservation is finished, the oil is cooled, and the oil temperature range is 50 +/-10 ℃.

7. The method of claim 6, wherein the ice cooling is performed within 2 hours after quenching, the temperature is less than-70 ℃, the cooling time is 2-2.5 hours, and then the cooling is performed to room temperature.

8. The method according to claim 7, wherein the tempering is performed within 2 hours after the ice-cooling is completed, at a temperature within 200 ± 10 ℃ for 3 to 3.5 hours, and then air-cooled to room temperature.

Technical Field

The invention relates to the field of heat treatment, in particular to a heat treatment method for superficial carburization of steel.

Background

The 16Cr3NiWMoVNbE is developed according to XXX10 engine, based on Д -39 Ш (16 KHz 3 NbM Б - Ш) steel, the novel multi-element composite thermal strength steel gear steel developed by domestic steel works has excellent processing performance and use performance, compared with 12Cr2Ni4A and other gear carburized steel which can only be used below 170 ℃, the 16Cr3NiWMoVNbE carbon steel has better comprehensive performance, such as strength, grain growth tendency, hardenability and the like which are superior to 12Cr2Ni4A, and can meet the requirement of high working temperature of the gear meshing surface of a new generation engine being more than or equal to 300 ℃, the current 16Cr3NiWMoVNbE high-quality carburized steel is successfully applied to various batch production and scientific research products of our factory, the requirement of the depth of the carburized layer of the process of the gear part using the material in certain auxiliary power device model is mostly 0.5-0.7 HR or more than or 0.64 HR of the carburized layer, and the conventional process parameters are similar to the current process of the superficial hardness of the alloy 3988.

Disclosure of Invention

The invention aims to provide an optimized solution for superficial carburization of 16Cr3NiWMoVNbE steel, which can ensure that the hardness of a superficial carburized position reaches HR15N not less than 88, the core hardness reaches HRC 35-46, and the carburized layer meets the requirements on the premise of meeting the corresponding mechanical property requirements, and meanwhile, parts have smaller heat treatment deformation.

The invention provides a heat treatment method for superficial carburization of steel, which comprises the following steps:

copper plating protection is carried out on a non-carburized area of the part; the part includes a non-carburized region and a carburized region;

cleaning a carburized surface of a carburized area;

performing primary carburization on a carburized surface in a controlled atmosphere furnace; wherein, in the second stage of the first carburization, the carbon potential range is 0.75 +/-0.05% C; the first carburization comprises two sections;

quenching, high-temperature tempering and copper removal are carried out after the parts are carburized.

Further, the method further comprises:

carrying out integral copper plating on the final part;

performing secondary carburization on the whole copper-plated part in a controlled atmosphere furnace;

and quenching, ice-cooling, tempering and inspecting the parts subjected to secondary carburization.

Further, the conditions for the first carburization include:

the range of the heat preservation temperature is 920 +/-10 ℃; the carbon potential range of the first section is 0.35 +/-0.05 percent C, and the heat preservation time range is 35 +/-5 min; the carbon potential range of the second section is 0.75 +/-0.05% C, the heat preservation time range is 50 +/-20 min, the furnace temperature reduction range is 840 +/-20 ℃, the carbon potential range is 0.75 +/-0.05% C, and the heat preservation time range is 20 +/-10 min.

Further, the thickness range of the copper layer plated with copper for the first time is 0.03-0.05 mm; the thickness range of the copper layer of the first copper plating is 0.02-0.04 mm.

Further, the conditions of the secondary carburization are as follows:

in a controlled atmosphere furnace, the temperature range is 910 +/-10 ℃, the carbon potential range is 0.4 +/-0.1 percent C, and the temperature range is 50 +/-20 min.

Further, quenching conditions are as follows: after the heat preservation is finished, the oil is cooled, and the oil temperature range is 50 +/-10 ℃.

Further, ice cooling needs to be carried out within 2 hours after quenching is finished, the temperature is lower than-70 ℃, the cooling time is 2-2.5 hours, and then the steel is cooled to room temperature in an air cooling mode.

Further, tempering is carried out within 2 hours after ice cooling is finished, the temperature range is 200 +/-10 ℃, the time range is 3-3.5 hours, and then air cooling is carried out to the room temperature.

According to the invention, through the research on the material carburization characteristics of the system, the influence of key factors such as different carburization carbon potentials, quenching temperature and time, tempering temperature and time, ice-cooling temperature and ice-cooling time and the like on the quality and performance of a carburized layer is mainly analyzed. Through multiple tests with different parameters, hardness and performance data are subjected to statistical analysis, reasonable carburizing, quenching, ice-cooling and tempering heat treatment process parameters are determined, and the problems that the depth of a carburized layer of a part is easy to be out of tolerance, the part deforms seriously and the like in the conventional process parameters are solved while relevant requirements of surface hardness, core hardness, performance and the like after heat treatment are ensured.

Detailed Description

The specific implementation steps are as follows:

(1) copper plating protection is carried out on a non-carburized area, and the thickness of a copper layer is 0.05 mm;

(2) cleaning the carburized surface of the part by using a sand blasting machine, wherein the sand blasting pressure is 0.25Mpa until the part is grey white, and then performing carburization within 1 hour;

(3) carburizing the carburized surface in a controlled atmosphere furnace. Keeping the temperature at 920 ℃, keeping the carbon potential of 0.35% C at the first stage for 35min, keeping the carbon potential of 0.75% C at the second stage for 50min, cooling to 840 ℃ along with the furnace, keeping the carbon potential at 0.75% C for 20min, and cooling in a protective atmosphere after the heat preservation is finished.

(4) Tempering the part at high temperature within 8 hours after carburization, tempering at 680 ℃ in a protective atmosphere furnace for 5.5 hours, and quickly cooling the part to room temperature along with the furnace after heat preservation;

(5) copper-removing sand blowing for parts

(6) The whole part is plated with copper with the thickness of 0.04mm

(7) Keeping the temperature in a controlled atmosphere furnace at 910 ℃ and 0.4% C of carbon potential for 50min, and cooling the furnace with oil at 50 ℃.

(8) Cooling the part with ice within 2h after quenching, wherein the temperature is-80 ℃, the time is 2h, and then cooling the part with air to room temperature;

(5) tempering the part within 2 hours after the ice cooling is finished, wherein the temperature is 200 ℃, the time is 3 hours, and then air cooling to room temperature;

(6) and (6) checking.