SUS304不銹鋼為目前核電廠管路最常使用之材料，惟在銲接修補過程，最常産生熱裂(hot cracking) 現象，為沃斯田鐵型不銹鋼被覆銲接過程最容易産生之問題。本研究針對低含碳量之SUS 304L不銹鋼，以GTAW進行表面IN 52M被覆，藉由不同被覆參數之選用，進行被覆層稀釋率分析，可調應變試驗裂紋敏感性量測，被覆界面層、部份融熔區、熱影響區及母材區之金相顯微組織觀察，電子顯微鏡被覆層表面狀態、析出物觀察及微硬度分析等。
研究結果顯示，被覆層最適參數為電流90A，被覆速度100 mm/min、送線速度400 mm/min，入熱量約810 J/mm及用氬氣為保護氣體，流量為15 L/min；SUS 304L不銹鋼界面層區金相組織為樹枝晶狀結構，而無明顯之熱影響區，δ-ferrite於母材部份熔融區成長；因多道次被覆，故下被覆層，在經過多次熱循環後，因再熱使得晶粒細化硬度提高；同時該被覆層界面硬度值為Hv210，較被覆材IN 52M硬度Hv149及SUS 304L硬度Hv190為高。在EDS成份分析中，當被覆材IN 52M累計被覆至第三層時，該層的化學成分已趨近於IN 52M素材，其硬度值亦隨被覆層增加而降低，惟仍較原素材為高。另外被覆層並無凝固熱裂紋及延性降低裂紋産生之發現。

SUS 304 stainless steel is the most popular pipe materials used in modern nuclear power plant. However, hot cracking problem is often encountered during the cladding of these types of austenite stainless steel. The study comprises the cladding of SUS 304L stainless steel with IN 52M materials by Gas Tungsten Arch Welding (GTAW). Variable cladding parameters, cladding dilution analysis and microstructure observations of SUS 304L stainless steel cladding with IN 52M have been investigated. The interface layer between SUS 304L stainless steel and cladding materials was dendrite structure without obvious HAZ occurred and δ-ferrite growth in fusion zone during the appropriate selection of cladding parameters with 90Amperes current, 100mm/min cladding speed, 400mm/min feed wire speed, 810J/mm heat input and Argon as an inert gas. According to multi-cladding process, repeated thermal cycle will resulted in the hardness of interface layer higher than both IN 52M cladding material and SUS 304L base metals. The EDS analysis shows the consecutive third layer cladding with similar chemical composition to IN 52M cladding materials and the third layer hardness decreases with increasing layers of cladding. Moreover, there is no hot cracking or fissures found in cladding layers.

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