| Summary: | 碩士 === 義守大學 === 材料科學與工程學系碩士班 === 93 === Stainless steel has been extensively used in modern human life. If a special property, such as antibacterial property is introduced to the alloy, it will substantially increase the value of stainless steel. The goal of this proposed research is to investigate the effects of copper content and aging treatment on antimicrobial activity and mechanical properties of martensitic stainless steels.
Martensitic stainless steels contain 11~18％ Cr and 0.1~1.2％C. One of the major applications of martensitic is for cutlery. Martensitic stainless steels are austenitic at temperature of 950~1000℃ but transform to martensitic on cooling. The Ms temperature of 0.1％C、12％Cr steels is about 300℃,with the Mf temperature is the range 100~150℃. It is essential to avoid the range 400~500℃ to temper the martensitic stainless steels, where secondary hardening occurs, since it corresponds both to poor toughness and a low 0.2％ YS/UTS ratio. Tempering to the over-aged condition restores the proof stress to a high level, and also causes a marked increase in the impact toughness. These steels can be tempered at higher temperatures of the order of 600~650℃ to produce good toughness at lower strength, but the optimum stress corrosion resistance. Cu-containing stainless steels with antimicrobial treatment will precipitate ε-Cu in matrix while give these steels antimicrobial activity against various bacteria. For antimicrobial martensitic stainless steels it is necessary to contain 0.3~3.0％Cu. In addition, copper has only a moderate effect on the impact strength and ductility of martensitic stainless steels.
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