Microstructure and mechanical properties evolution of Q235 steel surface modified by laser melting
To study the effect of laser power and scanning speed on the microstructure and macroscopic mechanical properties of Q235 material surface in laser melting,simulation software was used to simulate the change process of the molten pool when Q235 was irradiated by laser,and the temperature change trend of key points was monitored over time.Metallographic analysis software was used to analyze the microstructure of Q235 precipitated after temperature rise and rapid temperature drop.The metallographic microstructure of the material after laser scanning was observed by metallographic microscope using single factor laser melting experiment.The results show that the ferrite and pearlite of Q235 base metal form austenite completely after melting,and then form bainite and martensite after rapid cooling.The results of metallographic analysis verify the validity of the numerical simulation results.The analysis of microstructure and mechanical properties shows that the strength of the material is improved with the increase of scanning power at a certain scanning speed,and the elongation of the material is also improved with the laser power of 1 250 W compared with the laser power of 1 000 W;after laser treatment of the surface,the overall tensile strength increased,while the elongation decreased.The research results can provide a new process for improving the mechanical properties of Q235 steel.
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