| Summary: | 碩士 === 義守大學 === 機械與自動化工程學系碩士班 === 98 === The exterior smoothness of a stainless steel product is one of the key factors that make the product marketable or not. If the yield point elongation (YPE) phenomenon of a 430 stainless steel is not effectively reduced in its process of production, unsmooth lines, also known as Lüders bands, will appear on the surface of the product and lower its marketability. Consequently, the YPE phenomenon of a 430 stainless steel must be effectively controlled before it is further processed. This so-called YPE phenomenon emerges when the material is stressed by an external force, the interactions between moving dislocations and carbon/nitrogen atoms will result in irregular YPE phenomena. This study investigates different YPE phenomenon of a 430 stainless steel by tensile tests of furnace cooling, air cooling and water quenching specimens. With the help of Scanning Electronic Microscope (SEM) to examine the microstructure of material and its Energy Dispersive X-Ray Spectroscopy (EDS) to identify the carbon contents of both carbides and grain matrices, The YPE phenomenon of different cooling methods is related to the carbon contents; water quenching specimens show low carbon contents in grain matrices and no YPE phenomenon. It therefore proves that water quenching method can effectively reduce the YPE phenomenon in producing a 430 stainless steel.
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