本研究針對核電廠反應爐中600合金管路與308不銹鋼平板之異材銲接SCC破損案例，計劃以抗蝕性更佳的690合金取代600合金，而304L不銹鋼取代308不銹鋼，配合高能量密度與低入熱量特性的電子束銲接製程，分別進行的材料自體與異種對接銲，探討不同EBW銲接參數對於銲件微觀組織、機械性質與腐蝕行為所造成的影響。
實驗首先以BOP(bead on plate)方式，了解銲接參數對於3mm板厚的690合金與304L不銹鋼穿透深度之影響，之後將評估所得貫穿參數，進行兩材料對接銲實驗與銲後銲件的分析研究。
BOP實驗結果顯示，材料的EBW穿透深度隨著入熱量的提昇而逐漸增加，當達到臨界貫穿條件時，銲件表面具有較佳完整性，此條件應為材料最佳自體對接銲之銲接參數。但實際對接銲接時，因對接縫的存在，BOP實驗所得參數利用於690合金與304L不銹鋼自體對接銲接時，銲接參數需做小幅修改。
對接銲研究顯示，自體對接銲件微硬度值，因銲接參數入熱量變化不大而與母材相近。相對地，異種對接銲件受到母材稀釋量的不同造成合金成份有所差異，顯著地影響熔融區硬度表現，其中304L不銹鋼稀釋量多時(高Fe低Ni)，微硬度相較於母材呈現下降現象；而690合金稀釋量多銲件(高Ni低Fe)，硬度與690母材相近。
抗拉強度之結果，690合金自體對接銲件抗拉強度比母材稍低，而304L自體對接銲具優良機械性質，抗拉強度高於母材。異種對接銲之高Ni低Fe含量的銲件，抗拉強度與690合金自體銲件接近。
對接銲件因EBW快速凝固作用，金相觀察顯示次晶組織非常細密，且無明顯偏析物出現，腐蝕試驗顯示抗IGC能力優良。其中690合金自體對接銲件僅次晶間有些微孔蝕出現，而304L自體對接銲件為沃斯田鐵次晶間的δ-肥粒鐵易受到腐蝕液的浸蝕較為明顯。異種對接銲件熔融區抗蝕能力受到合金成份的差異，腐蝕金相變化大，當304L稀釋量較多時，熔融區次晶晶界受到浸蝕而明顯顯現，690合金稀釋量多時，熔融區腐蝕金相出現部分孔蝕，抗蝕能力佳。

Regarding the SCC of alloy 600 tube and 308 SS plate dissimilar weldment at the reactor of nuclear power plant, in this study EBW is used to joint alloy 690 and 304L SS plates to replace the alloy 600 and 308 SS to get their autogenous and dissimilar weldments individually. The purpose of this study is to discuss the effect on microstructure, mechanical properties and corrosion behavior of these resulting weldments with different EBW parameter.
At first, the bead on plate (BOP) method is used to understand the effect on EBW penetration of 3mm alloy 690 and 304L SS plate resulting from different welding parameter. Then the parameters are evaluated and used to proceed with the alloy 690 and 304L SS plate autogenous and dissimilar welding.
The BOP experiments show that the EBW penetration is increased with increasing heat input. When the critical penetration condition is attained, the weldment surface is usually integrated, and the parameter of this condition is the best parameter for autogenous butt-welding. However, because of the plate-butt seam existing during autogenous butt-welding, the critical BOP parameters need a little correction to proceed with alloy 690 and 304L SS autogenous welding.
According to the butt-welding result, the microhardness of autogenous welding fusion zone is close to their basemetal, for the variation of parameter heat input is unobvious. Relatively, due to the basemetal dilution is diverse, the dissimilar welding fusion zone composition is different, and their hardness will change obviously. When 304L SS dilution in fusion zone is more, the hardness is lower than both basemetal; alloy 690 dilution is more, the hardness is near alloy 690 basemetal.
After tensile test, the tensile strength of alloy 690 autogenous weldment is little lower than alloy 690 basemetal. And 304L SS autogenous weldment have good mechanical property, for tensile strength is higher than 304L SS. Otherwise, when alloy 690 dilution is more in fusion zone, its weldment tensile strength is near alloy 690 autogenous one.
Owing rapid solidification of EBW, the subgrain organization of butt weldment is fine and microsegregation is unapparent to make IGC resistant ability well. According to the result of Modified Huey test, there is light pitting at subgrain boundary in alloy 690 autogenous weldment only. And 304L SS autogenous weldment reveals that δ-ferrite between austenite subgrain is easy to be etched. Finally, the resistant ability of dissimilar weldment changes greatly while their fusion zone composition is different. If there is more 304L SS dilution in fusion zone, the subgrain boundary of the fusion zone will be easy to be etched and viewed clearly. If there is more alloy 690 dilution in fusion zone, there will be a few pitting in it, then the resistance ability will be nice.

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