| Summary: | 碩士 === 國立雲林科技大學 === 機械工程系 === 106 === Due to international competition of the hand tool industry, in recent years, the application of non-traditional heat treatment technology has become popularity. It is more time-saving and environment-friendly than traditional heat treatment processes. Laser heat treatment has a high energy density, a small thermal deformation, and a short processing time. Laser heat treatment is easy to perform surface quenching on local area and suitable for surface hardening treatment of hand tool edge. In this research, the fiber laser is applied to treat the surface of hand tool steels 50BV30 and spheroidized 50BV30 materials. Spheroidizing treatment can enhance the ductility of steel and can also make reduce cracking and deformation after quenching treatment. The effects of laser power, scan rate and spot size on microstructure, corrosion and mechanical properties were studied by metallographic observation, analysis of microhardness and electrochemical corrosion testing.
According to the results, martensite was observed by scan rate of 10mm/s with different laser power. The hardness of the area after laser heat treatment is higher than the hardness of substrate. The highest hardness is Hv676 after 400W and scan rate of 100mm/s laser treatment. As the laser power enhance and scan rate decrease, the depth and width of the hardened layer gradually increase. The depth of the hard-ened layer can reach 700 μm after 400W and rate of 10 mm/s laser treatment. The corrosion resistance of 50BV30 and spheroidized 50BV30 was not effected by laser heat treatment.
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