Study On TiN/Ni Alloying Of 38CrMoAl Gear Steel By Scanning Electron Beam

38CrMoAl alloy steel has high strength and hardness due to its good plasticity and toughness.It is often used to manufacture moving parts with high wear resistance and high fatigue strength.The high power density of electron beam heating can make the material surface melt in a short time.The good heat transfer foundation can make the metal surface obtain a large solidification speed,so as to improve the surface properties of 38 CrMoAl Steel and expand its application range.In order to improve the surface strength of gear steel 38 CrMoAl,Tin/Ni alloy layer with good mechanical properties was prepared by continuous scanning electron beam.In this experiment,Tin/Ni precoating layer was prepared on the steel surface by plasma thermal spraying technology,then it was treated by scanning electron beam alloying,with the help of SEM,EDS,XRD,Vickers hardness tester,friction and wear testing machine and other modern testing means.The effects of Tin / Ni addition on the microstructure and mechanical properties of the alloying layer on the surface of the scanning electron beam were discussed.The effects of electron beam process parameters on the microstructure and mechanical properties of the alloying layer were discussed.The effects of the thickness of the precoating layer and the angle of surface inclination on the microstructure and mechanical properties of the alloying layer were investigated.The results show that after Tin/Ni alloying on the surface of 38 CrMoAl Steel by continuous scanning electron beam technology,the cross section of the sample consists of three parts: alloying layer,heat affected zone and matrix.When the Tin content reaches20%,the surface layer of alloying layer is mainly composed of equiaxed crystal and columnar crystal,and the equiaxed crystal is fine and evenly distributed.The surface hardness of the alloyed layer increases first and then decreases with the increase of the beam current.With the increase of the beam current,the wear loss decreases first and then increases.With the increase of the electron gun horizontal velocity,the grains on the top of the alloying layer are refined,and the maximum microhardness of the cross section increases first and then decreases with the increase of the electron beam current.With the increase of the thickness of the pre coating layer,the Tin content on the surface of the alloy layer increases,and the hardness of the alloy layer first increases and then decreases.With the increase of the surface inclination angle,the Tin content on the surface of the alloyed layer decreases,and the microhardness of the alloyed layer decreases.