CN115961121A

CN115961121A - Method for treating 30CrMo steel by electron beams

Info

Publication number: CN115961121A
Application number: CN202111184697.9A
Authority: CN
Inventors: 郭金科; 王荣; 李新凯
Original assignee: Guilin University of Electronic Technology
Current assignee: Guilin University of Electronic Technology
Priority date: 2021-10-12
Filing date: 2021-10-12
Publication date: 2023-04-14

Abstract

The invention discloses a method for treating 30CrMo steel by electron beams, which specifically comprises the following steps: step 1: and (4) preprocessing, namely milling the cut test block workpiece, and then cleaning the milled workpiece by using a cleaning solvent. Step 2: and (4) electron beam treatment, namely continuously treating the surface of the workpiece by using an electron beam. And 3, step 3: and (3) testing the structure and the performance, namely measuring the surface friction wear appearance through a laser microscope, observing the internal structure through an electron microscope, and measuring the hardness through a microhardness meter and detecting the wear resistance through a friction wear testing machine. Namely, the method disclosed by the invention not only can improve the surface hardness of the 30CrMo steel, but also can improve the wear resistance of the test block, and has a good application scene.

Description

Method for treating 30CrMo steel by electron beams

Technical Field

The invention belongs to the technical field of high-energy beam surface modification of 30CrMo steel, and particularly relates to a method for treating 30CrMo steel by using an electron beam.

Background

The 30CrMo steel has the advantages of high strength, high toughness and the like, and is increasingly applied to the field of industrial production and processing. But inevitably serves in a severe environment in the practical application process, the surface of the 30CrMo steel generates friction and wear, and the fatigue of the contact surface is an important reason for the failure of the steel.

The electron beam surface modification technology is used as a novel high-energy beam treatment material surface technology, has the advantages of energy utilization rate of more than 90 percent, remarkable improvement effect and the like, and has wide prospect in actual production. However, the electron beam has a large and uneven energy effect per unit area on the surface of the material, which affects the actual improvement effect. Therefore, the patent provides a method for treating the surface of 30CrMo steel by using electron beams, which can improve the surface hardness of the 30CrMo steel, improve the wear resistance of a test block, apply mechanism research and experimental conclusion to surface modification of other metal materials and expand the field of surface processing of high-energy beam materials.

Disclosure of Invention

The purpose of the invention is: milling and cutting a 30CrMo steel workpiece, and cleaning a milled test block by using acetone and an absolute ethyl alcohol solvent; and finally, obtaining a finished sample product through electron beam treatment. The invention can improve the surface wear resistance of the test block while effectively improving the surface hardness, and has excellent practical application scenes.

In order to solve the problem of complaints, the technical scheme adopted by the invention is as follows: a method for electron beam treatment of 30CrMo steel comprises a plurality of steps.

1. A method for treating 30CrMo steel by electron beams.

Step 1: and (2) preprocessing, namely milling the cut test block workpiece, and then cleaning the milled workpiece by using acetone and an absolute ethyl alcohol solvent to remove oil stains and impurities on the surface.

After step 1, step 2 is performed.

And 2, step: and (3) electron beam treatment, namely placing the workpiece after quenching and tempering and cleaning in a thermal processing chamber of an electron beam welding machine, and vacuumizing the electron gun chamber and the welding processing chamber by connecting a diffusion pump and a roots pump in series, so that the vacuum degree of the electron gun chamber is 1.33 multiplied by 10 < -3 > Pa, and the vacuum degree of the processing chamber is 5 multiplied by 10 < -2 > Pa. Setting technological parameters of an electron beam welding machine, wherein the acceleration voltage of an electron beam is 60KV, the beam current of an electron beam machining is 8mA, 9mA and 10mA, the moving speed of an electron gun is 3 mm/s, 5 mm/s and 7mm/s, and the diameter of a beam spot of the electron beam is 5mm. And then, performing surface treatment on the workpiece subjected to the electron beam cleaning treatment to obtain a finished product.

After step 2 is completed, step 3 is performed.

And step 3: and (3) performing structure and performance test, namely observing the structure of the test block by using a GeminiSEM300 electron microscope, measuring the microhardness of the workpiece by using an HDX-1000TM microhardness tester under the load of 1.96N and the loading time of 15s, and measuring the surface wear resistance of the workpiece by using an HSR-2M friction wear tester under the conditions of the load of 20N and the reciprocating length of 3mm for 40 min. The abrasion loss of the sample was measured with an FA1104N electronic balance with a balance accuracy of 0.0001g.

2. A method of electron beam treatment of 30CrMo steel according to claim 1, characterized by: cutting treatment is needed before the step 1, a 30CrMo steel workpiece is cut into test blocks of 40mm multiplied by 40mm by adopting a numerical control milling machine, the feed amount of each workpiece is kept consistent and the milling speed is kept the same in the milling process, and the milled test blocks are obtained.

3. A method of electron beam treatment of 30CrMo steel according to claim 1, characterized in that: the main components of the cleaning solvent in the step 1 are acetone and absolute ethyl alcohol. Compared with the prior art, the invention has a plurality of beneficial effects.

1. According to the invention, the surface of the 30CrMo steel is treated by adopting the electron beam, so that the surface hardness is improved, and the surface wear resistance of the sample can be effectively improved. The invention adopts an electron beam treatment mode to rapidly heat the 30CrMo steel to reach the melting point of the material, and then rapidly cool the material. The rapid temperature rise and quenching process enables the surface of the test block to be rapidly hardened, and the overall improvement of the surface hardness and the wear resistance of the test block is realized.

2. When the 30CrMo steel is treated by the continuous electron beams, the electron beams act on the surface of the test block, and a large amount of heat is generated in a short time and then is diffused and dissipated. Because the cooling speed of the matrix is higher, the material melting layer and the heat affected zone tissues grow and thin in a rapid heating and rapid cooling mode, the surface hardness and the wear resistance are improved, and the quenching effect is similar to the heat treatment quenching effect. The test block matrix has low heating temperature, unchanged internal structure and high toughness inside the material. The present invention thus achieves an overall improvement in surface properties such as hardness, abrasion resistance, etc.

3. The process of treating the 30CrMo steel by the electron beam is carried out in a vacuum processing chamber, so that the environment is not polluted in the processing process, and the 30CrMo steel is prevented from contacting the outside; meanwhile, the energy transfer medium is electrons, and has the characteristics of high energy conversion, good action effect and the like.

4. The microhardness of the 30CrMo steel matrix prepared by the invention is 280.30HV, the microhardness of the heavy melting layer is 607.58HV, and the hardness of the heavy melting layer is 2.17 times of the hardness of the matrix. Namely, the surface hardness of the 30CrMo steel test block is obviously improved by the electron beam treatment of the invention. Under the load of 20N, the reciprocating length is 3mm, the abrasion weight loss is only 0.6mg after the test is carried out for 40min, and the abrasion weight is greatly improved compared with that of a test block which is not treated by an electron beam and has 1.2 mg.

[ description of the drawings ]

FIG. 1 is a surface topography of a 30CrMo steel prior to the practice of the invention.

FIG. 2 is a surface topography of 30CrMo steel obtained after the practice of the invention.

FIG. 3 shows a cross-sectional microstructure of a 30CrMo steel obtained by carrying out the invention.

FIG. 4 shows the remelted layer microstructure of a 30CrMo steel obtained after the practice of the present invention.

[ detailed description ] A

The following are specific embodiments of the present invention, and the embodiments of the present invention will be further described with reference to the drawings, but the present invention is not limited to these embodiments.

A method for electron beam treatment of 30CrMo steel comprises a plurality of steps.

Step 1: and (3) preprocessing, namely milling the cut test block workpiece, and then cleaning the milled workpiece by using acetone and absolute ethyl alcohol solvent to remove oil stains and impurities on the surface.

After step 1 is completed, step 2 is performed.

Step 2: and (2) electron beam treatment, namely placing the cleaned workpiece in a thermal processing chamber of an electron beam welding machine, and vacuumizing the electron gun chamber and the welding processing chamber by using a diffusion pump and a Roots pump connected in series, so that the vacuum degree of the electron gun chamber is 1.33 multiplied by 10^ (-3) Pa, and the vacuum degree of the processing chamber is 5 multiplied by 10^ (-2) Pa. Setting the technological parameters of the electron beam welding machine, wherein the acceleration voltage of the electron beam is 60KV, the processing beam current of the electron beam is 8mA, 9mA and 10mA, the moving speed of the electron gun is 3 mm/s, 5 mm/s and 7mm/s, and the diameter of the beam spot of the electron beam is 5mm. And then, carrying out surface treatment on the workpiece subjected to the electron beam cleaning treatment to obtain a finished product.

After step 2, step 3 is performed.

And step 3: and (3) performing structure and performance test, namely observing the structure of the test block by using a GeminiSEM300 electron microscope, measuring the microhardness of the workpiece by using an HDX-1000TM microhardness tester under the load of 1.96N and the loading time of 15s, and measuring the surface wear resistance of the workpiece by using an HSR-2M friction wear tester under the conditions of the load of 20N and the reciprocating length of 3mm for 40 min. The abrasion weight loss of the sample was measured with an electronic balance of FA1104N type with a balance accuracy of 0.0001g.

The microhardness of the workpiece is measured by an HDX-1000TM microhardness meter under the load of 1.96N and the loading time of 15s, the microhardness of a remelted layer is 607.58HV, the microhardness of a matrix is 280.30HV, and the hardness of the remelted layer is improved by 2.17 times.

The surface topography of the 30CrMo steel test block without electron beam treatment and the test block with electron beam treatment was observed under a 3D measurement laser microscope as shown in fig. 1 and 2. As can be seen from fig. 1 and 2: in fig. 1, the number of furrows on the abraded surface of the 30CrMo steel which is not subjected to scanning electron beam treatment is large, pits and protrusions exist on the surface, tool marks on the surface of the 30CrMo steel implemented by the method in fig. 2 disappear, and the surface appearance is improved.

The block tissue was observed using a GeminiSEM300 electron microscope, as shown in fig. 3 and 4. Wherein, FIG. 3 is a microscopic structure diagram of a test block section magnified to 200 times, the section appearance is divided into a remelting layer, a heat affected zone and a matrix, and the distribution boundary of a modification layer and the matrix is more obvious; FIG. 4 is a structure diagram of a re-melted layer of a test block magnified to 2000 times, wherein grain boundaries disappear, the structure is uniformly distributed, and surface grains are significantly refined, so that the surface properties such as hardness and wear resistance are improved.

The HSR-2M friction wear testing machine is tested for 40min under the load of 20N and the reciprocating length is 3mm, the wear resistance of a workpiece is measured, and the abrasion weight loss of a sample is measured by using an FA1104N type electronic balance. Compared with the test block before electron beam treatment, the abrasion loss of the test block is 1.2mg, the abrasion of the test block is reduced by 0.6mg after the test block is abraded for 40min, and the abrasion resistance is improved.

The above description is specific to possible embodiments of the present invention, but the embodiments are not intended to limit the scope of the claims of the present invention, and all equivalent changes and modifications made within the technical spirit of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A method of electron beam treating a 30CrMo steel comprising the steps of:

step 1: pre-treatment, milling the cut test block workpiece, and then cleaning the milled workpiece by using acetone and an absolute ethyl alcohol solvent to remove oil stains and impurities on the surface;

after the step 1 is finished, performing a step 2;

step 2: electron beam treatment, placing the treated and cleaned workpiece in the heat processing chamber of electron beam welding machine, using diffusion pump to series-connect Roots pump to vacuum the electron gun chamber and welding processing chamber to make the vacuum degree of the electron gun chamber be 1.33

Pa, a vacuum degree of the processing chamber of 5 ×/or>

Pa; setting the technological parameters of an electron beam welding machine, wherein the acceleration voltage of an electron beam is 60KV, the processing beam current of the electron beam is 8mA, 9mA and 10mA, the moving speed of an electron gun is 3 mm/s, 5 mm/s and 7mm/s, and the diameter of a beam spot of the electron beam is 5mm; then, performing surface treatment on the workpiece subjected to the electron beam cleaning treatment to obtain a finished product;

step 3 is carried out after step 2 is finished;

and step 3: testing the structure and the performance, namely observing the structure of a test block by using a GeminiSEM300 electron microscope, and measuring the microhardness of the workpiece by using an HDX-1000TM microhardness tester under the conditions of 1.96N load and 15s loading time; the abrasion weight loss of the sample was measured with an electronic balance of FA1104N type with a balance accuracy of 0.0001g.

2. A method of electron beam treatment of 30CrMo steel according to claim 1, characterized by: cutting treatment is needed before the step 1, a 30CrMo steel workpiece is cut into test blocks of 40mm multiplied by 40mm by a numerical control milling machine, the feed amount of each workpiece is kept consistent and the milling speed is kept the same in the milling process, and the milled test blocks are obtained.

3. A method of electron beam treatment of 30CrMo steel according to claim 1, characterized in that: the main components of the cleaning solvent in the step 1 are acetone and absolute ethyl alcohol.