阅读说明：本技术 一种高强韧钢细长台阶轴的防变形调质方法 (Deformation-preventing tempering method for high-strength and high-toughness steel long step shaft ) 是由 王艳超 高军 华金虎 杨秀珍 张贺清 刘庆君 余国俊 王全福 白燕芳 王一江 李 于 2020-12-17 设计创作，主要内容包括：本发明涉及一种高强韧钢细长台阶轴的防变形调质方法,选择井式电炉进行调质处理,采用竖直吊挂的装卡方式；毛坯淬火加热出炉后空气预冷,预冷至毛坯最细部位的表面温度到达500～550℃后,淬入一定浓度的无机淬火剂聚乙烯醇水溶液中,冷却一定时间后进行两次不同温度的高温回火处理,本发明本发明从调质处理的装卡方式、减小淬火应力、去除应力和性能回火方面优化设计调质工艺过程和工艺参数,达到台阶轴要求的性能,减少变形和校正工作。力学性能达到技术要求(ReL≥1200MPa,Z≥35％,KU2≥50J),变形量及校正工作减少60％。(The invention relates to a deformation-preventing tempering method for a high-strength and high-toughness steel long stepped shaft, wherein a well-type electric furnace is selected for tempering treatment, and a vertical hanging clamping mode is adopted; the method comprises the steps of quenching, heating and discharging a blank, precooling the blank with air until the surface temperature of the finest part of the blank reaches 500-550 ℃, quenching the blank into an inorganic quenching agent polyvinyl alcohol aqueous solution with a certain concentration, cooling for a certain time, and then carrying out high-temperature tempering treatment at different temperatures twice. The mechanical property reaches the technical requirements (ReL is more than or equal to 1200MPa, Z is more than or equal to 35 percent, KU2 is more than or equal to 50J), and the deformation and the correction work are reduced by 60 percent.)

1. The deformation-preventing quenching and tempering method for the long and thin stepped shaft of the high-strength and high-toughness steel is characterized by comprising the following steps of:

(1) selecting a well-type electric furnace for quenching and tempering treatment, and adopting a vertical hanging and clamping mode;

(2) quenching, heating and discharging the blank, precooling the blank with air until the surface temperature of the finest part of the blank reaches 500-550 ℃, quenching the blank into an inorganic quenching agent polyvinyl alcohol aqueous solution with a certain concentration, and cooling for a certain time;

(3) and performing high-temperature tempering treatment at different temperatures twice.

2. The deformation-preventing quenching and tempering method for the high-strength and high-toughness steel elongated stepped shaft according to claim 1, characterized in that the material of the elongated stepped shaft blank is 35CrNi3 MoVA.

3. The deformation-preventing quenching and tempering method for the high-strength and high-toughness steel elongated stepped shaft according to claim 1, characterized in that the diameter of the elongated stepped shaft blank is phi 130-phi 110, and the length is 5100 mm.

4. The deformation-preventing tempering method for the high-strength and high-toughness steel elongated stepped shaft according to claim 1, characterized in that in the step (2), the blank is quenched and heated at 830-850 ℃ and is discharged after being kept warm for 3-4 hours.

5. The deformation-preventing tempering method for the long and thin stepped shaft of the high strength and toughness steel according to claim 1, characterized in that in the step (2), the quenching is carried out in 0.1-0.20% concentration of inorganic quenching agent polyvinyl alcohol aqueous solution.

6. The deformation-preventing tempering method for the high-strength and high-toughness steel long step shaft according to claim 1, wherein in the step (2), the cooling time is 8-10 min.

7. The deformation-preventing tempering method for the high-strength and high-toughness steel elongated stepped shaft according to claim 1, characterized in that tempering is air cooling.

8. The deformation-preventing tempering method for the high-strength and high-toughness steel elongated step shaft according to claim 1, characterized in that in the step (1), a pit-type electric furnace with furnace temperature uniformity of +/-10 ℃ is selected for tempering treatment.

9. The deformation-preventing tempering method for the high-strength and high-toughness steel elongated stepped shaft according to claim 1, characterized in that in the step (3), high-temperature tempering is performed for 5-6 hours by performing heat preservation twice at 520-540 ℃ and 550-570 ℃ in sequence after quenching.

Technical Field

The invention belongs to the technical field of machine manufacturing, and particularly relates to a deformation-preventing tempering method for a high-strength and high-toughness steel long step shaft.

Background

The requirement of quenching and tempering strength of a certain step shaft is high (ReL is more than or equal to 1200MPa, Z is more than or equal to 35 percent, KU2 is more than or equal to 50J), the length-diameter ratio of a blank is large (phi 130-phi 110 multiplied by 5100mm), and the blank is very easy to bend and deform in the quenching and tempering heat treatment process and the machining process and cannot meet the technical requirement of product design. In order to meet the requirement of ensuring the processing, the process is frequently corrected, the workload is large, the production period is long, and the cost is high. Through statistics, the production and processing yield of the step shaft blank is only 43%, and the manufacturing cost is high.

Disclosure of Invention

The invention provides a deformation-preventing tempering method for a high-strength and high-toughness steel long step shaft, which aims to solve the technical problems that: in order to reduce the deformation of the step shaft blank in quenching and tempering heat treatment, the deformation in the machining process and the workload of deformation correction and shorten the machining period.

In order to solve the technical problems, the invention provides a deformation-preventing tempering method for a high-strength and high-toughness steel long step shaft, which is characterized by comprising the following steps of:

(1) selecting a well-type electric furnace for quenching and tempering treatment, and adopting a vertical hanging and clamping mode;

(2) quenching, heating and discharging the blank, precooling the blank with air until the surface temperature of the finest part of the blank reaches 500-550 ℃, quenching the blank into an inorganic quenching agent polyvinyl alcohol aqueous solution with a certain concentration, and cooling for a certain time;

(3) and performing high-temperature tempering treatment at different temperatures twice.

Further, the blank material of the slender step shaft is 35CrNi3 MoVA.

Further, the diameter of the slender step shaft blank is phi 130-phi 110, and the length is 5100 mm.

Further, in the step (2), the quenching heating temperature of the blank is 830-850 ℃, the temperature is kept for 3-4 hours, and then the blank is discharged.

Further, in the step (2), quenching is carried out in 0.1-0.20% inorganic quenching agent polyvinyl alcohol aqueous solution.

Further, in the step (2), the cooling time is 8-10 min.

In the step (1), a well-type electric furnace with furnace temperature uniformity of +/-10 ℃ is selected for quenching and tempering.

In the step (3), high-temperature tempering is sequentially carried out for heat preservation for 5-6 hours at 520-540 ℃ and 550-570 ℃ after quenching.

Has the advantages that: the invention adopts a well-type electric furnace treatment and a special tool vertical hanging clamping mode for a slender step shaft blank made of steel for high-strength and high-toughness materials under the condition of ensuring the quenching and tempering effects, adopts a pre-cooling quenching method for heat treatment, precools in air to a certain temperature and then quenches and cools, adopts an organic quenching agent with a certain concentration and a moderate cooling speed for cooling a cooling medium, and carries out tempering at different tempering temperatures twice to remove stress to the maximum extent, improve the mechanical property and reduce and control the heat treatment deformation, the processing process deformation and the deformation correction workload of the barrel blank. The invention optimally designs the hardening and tempering technological process and technological parameters from the aspects of hardening and tempering clamping mode, reducing quenching stress, removing stress and tempering performance, achieves the performance required by the step shaft, and reduces deformation and correction work. The quenching and tempering treatment of the slender step shaft blank made of steel for the high-toughness material can reduce quenching deformation and deformation correction work to the maximum extent while ensuring that the mechanical property reaches the requirements that ReL is more than or equal to 1200MPa, Z is more than or equal to 35 percent and KU2 is more than or equal to 50J.

Detailed Description

In order to make the objects, contents and advantages of the present invention clearer, the following detailed description of the embodiments of the present invention is provided.

The invention provides a deformation-preventing tempering method for a high-strength and high-toughness steel elongated stepped shaft, which takes the tempering treatment of an elongated stepped shaft blank (the diameter is 130-110 mm, the length is 5100mm) made of 35CrNi3MoVA steel used for high-strength and high-toughness materials as an example, and specifically comprises the following steps:

(1) selecting a well-type electric furnace with furnace temperature uniformity of +/-10 ℃ for quenching and tempering treatment, and adopting a vertical hanging and clamping mode;

(2) the optimal precooling temperature is selected by utilizing the stability of the austenitic structure and the martensite transformation temperature point of the high-strength and high-toughness steel, so that a good quenching effect is achieved: quenching and heating the blank at 830-850 ℃, keeping the temperature for 3-4 h, taking the blank out of the furnace, pre-cooling the blank by air, and beginning quenching and cooling the blank until the surface temperature of the finest part phi 110 of the blank reaches 500-550 ℃;

the cooling medium adopts a quenching agent polyvinyl alcohol aqueous solution with a slower cooling speed, the concentration is 0.1-0.20%, the cooling time is 8-10min, and the quenching stress is reduced;

(3) in order to eliminate quenching stress and improve mechanical property, high-temperature tempering treatment at different temperatures is carried out twice after quenching, the high-temperature tempering treatment is carried out at 520-540 ℃ and 550-570 ℃ for 5-6h, and the tempering is air cooling.

The 4 step shaft blanks subjected to trial production are detected by mechanical properties: the ReL is 1250-1290 MPa, the Z is 52-58 percent, and the KU2 is 34-43J, so that the technical requirements of the product are met; the external jump deformation of the quenched and tempered blank is reduced to 6mm from the original 15mm, the deformation is reduced by 60 percent, and the correction workload is reduced. And basically does not deform in the subsequent processing process. Various targets of deformation research are achieved.

The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.