| Summary: | 碩士 === 國立高雄第一科技大學 === 機械與自動化工程所 === 90 === In general, the high-speed tool or hot tool steel was selected as the material of the cutter. The hardness is from HRC62 to HRC65 after the heat treatment. However the rolling process is conducted in rolling wires, the cutter is under the environment of hot temperature and serves wear. The hardness of the cutter was decline due to the grain size coarsening, which results in the mill line abnormally shut down. It was worth researching to improve the life of the cutter.
In this study,the Stellite 1 cobalt-based alloy was cladding on JIS S45C medium carbon steel by laser. The improvement on the life of the cutter and the phase transformation after the heat treatment of the layer are investigated. The results show that the life of the cutter is elevated 6 times than that of the conventional cutter. It was observed that the microstructure and the hardness of the used cladding cutter are little differences than before. Then the Cobalt-based layer were conducted by the different heat treatment conditions to be homogenized When the temperature is over the 1000 ℃, the Cr segregation is dramatically eliminated. The highest hardness up to Hv700 occur at 1000℃.The hardness will increase Hv100 through tempering at 650℃ following the homogenization at 1000℃. During the homogenization, it is observed that M7C3 decomposed into M6C by XRD analysis. After tempering , M6C coherently precipitates in the Co-rich γmatrix by TEM analysis and the effect of precipitates hardening will be resulted in.
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