鎢含量對肥粒鐵型不銹鋼的顯微組織與腐蝕特性之研究

Effects of Tungsten Contents on the Microstructures and Corrosion Characteristics of Ferritic Stainless Steel

劉明德(Ming-Te Liu)

指導教授 ： 黃和悅

國立虎尾科技大學/工程學院/材料科學與工程系材料科學與綠色能源工程碩士班/碩士(2017年)

摘要

本研究以AISI430不銹鋼分別添加1wt.%、2wt.%及4wt.%的W元素，並以真空感應鑄造後施予退火熱處理，將熱處理完成的試片進行成分分析、硬度試驗、微觀結構分析及電化學極化曲線測試。由XRD分析顯示退火熱處理後各種參數之不銹鋼全由肥粒體與第二相(σ)組成。以掃描式電子顯微鏡與能量色散光譜儀來觀察微觀組織及成分分析，結果顯示第二相(σ)主要由Fe-Cr組成，第二相(σ)析出量會隨鎢元素添加量增加而遞減，而添加4wt.%的鎢元素之不銹鋼，其鎢元素有團聚情形。微硬度測試結果顯示第二相(σ)固溶回基地與鎢元素添加導致基地平均微小硬度值大幅度提高;電化學量測結果發現，其鎢元素添加能提高AISI430鈍化膜耐蝕性、提高孔蝕電位及降低腐蝕速率。

關鍵字

肥粒體不銹鋼 ； 真空鑄造 ； 鎢元素 ； 熱處理 ； σ相 ； 腐蝕

並列摘要

In this study, the effects of tungsten (1, 2 and 4 wt%) addition on the microstructure and corrosion characteristics of the vacuum casting ferritic stainless steel were investigated. The microstructures of the as-cast and heat-treated alloys with different tungsten additions were analyzed by optical microscope, X-ray diffraction and scanning electron microscopy. The corrosion resistance was evaluated by electrochemical techniques. The X-ray diffraction analysis showed that the ferritic stainless steel specimens were composed of ferrite and σ phase after heat treatment. The energy-dispersive X-ray spectroscopy revealed that the σ-phase was an intermetallic phase composed mainly of iron and chromium, which decreased with the increase of tungsten content. Besides, ferritic stainless steel containing up to 4 wt.% of tungsten resulted in the aggregation of tungsten particles. Tungsten was added to ferritic stainless steel could improve hardness and corrosion resistance.

並列關鍵字

Ferritic stainless steel ； Vacuum casting ； Tungsten ； Heat treatment ； Sigma phase ； Corrosion

參考文獻

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