Laser Surface Treatment Of H13 Steel And Microstructure And Properties Of Laser Cladding High Entropy Alloy

As a kind of hot forging mould steel commonly used in industry,H13 steel is subject to mechanical load and thermal shock for a long time,and the mould is susceptible to wear and heat fatigue.In order to improve the surface mechanical properties of H13steel and the service life of H13 steel mould,laser surface heat treatment and laser cladding high entropy alloy cladding technology were studied to improve the surface mechanical properties of H13 steel.The surface of H13 steel was heat treated by laser surface heat treatment technology,and a certain thickness of hardening layer was obtained,and the internal structure of H13 steel was kept unchanged.The surface of H13 steel was heat treated by laser surface heat treatment technology to obtain a certain depth of hardened area and keep the internal structure of H13 steel unchanged.In order to get the best parameters,the orthogonal experiment of power and scanning speed is designed.The optimal parameter:the power is 200W and the speed is 300mm/min.The results show that the change of power and traveling speed has little effect on the width of hardened layer.The power has a great influence on depth of the hardened layer.The higher the power can get the greater depth of the hardened layer.With the increase of traveling speed,the depth of hardened layer decreases gradually.When the power is 200W and the speed is 300mm/min,H13 steel can get the best average hardness,768.3HV.With the increase of defocusing amount,the hardening depth first increases and then decreases.When the defocusing amount is 3 mm,a better morphology and higher hardness of the hardening region can be obtained.The surface oxide layer can improve the ability of the surface of H13 steel absorbing laser energy,but it will reduce the surface hardness.The results show that the wear resistance of H13 steel is better than that of H13 steel.On the surface of H13 steel prepared Co_1.5CrFeNi_1.5Ti_0.75high-entropy alloy coating by laser cladding,the influence of power and scanning speed on the formation of high entropy alloy cladding layer was studied.When the power is 200 W and the speed is 300mm/min,the best average hardness of the cladding layer is 643.1 HV,and the wear resistance also is the best.The phase structure of the cladding layer is BCC and FCC.The effect of Nb content on the microstructure and properties of high entropy alloy laser cladding coating was investigated.The highest average hardness,810.3HV,is obtained when the Nb content is 0.5at.%.Meanwhile,the wear resistance of the cladding coating is the best.With the increase of Nb content,the wear resistance first increases and then decreases.The phase structure of the cladding layer is BCC phase,FCC phase and Laves phase.With the increase of Nb content,Laves phase increases.