| Summary: | 碩士 === 正修科技大學 === 機電工程研究所 === 97 === The purpose of this study is to assist Taiwan Plasma Co., Ltd. to manufacture the wear-resistant plate with PTA hard-facing method. The operation current, powder feeding rate, torch moving rate and torch moving distance were four most important parameters in accordance with the experiences of Taiwan Plasma. Taguchi methodology is used to make the association of these parameters in optimization and through the observation of metallographic, hardness, ASTM G65 abrasion test and dilution rate to evaluate the effects of these parameters on the hardfacing layer of the wear-resistant plate.
The results show that the most sensitive parameter for the surface hardness is the torch moving distance with a minimum effect of the operation current, under the parameters in optimization. For the abrasion performance, torch moving rate is the most effective parameter with a minimum effect of the powder feeding rate. The most sensitive parameter for the dilution rate is the operation current with a minimum effect of the torch moving distance. According the observation of the metallographic structure, if the tree-structure segregation of Fe-Cr-C is more robust then the structure of Fe-Cr-C is denser, results in a higher surface hardness, and improves the wear resistance performance obviously. Through this PTA hardfacing technology, the heat-affected zone of the substrate for a 4mm low-carbon steel plate can be controlled within 0.2mm in depth. In addition to the operation current, the powder feeding rate and the torch moving rate are also considerable important in the manufacturing.
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