本研究探討A508低合金鋼與SS304L不銹鋼異質銲接件之機械性質及微結構。以鎢極氣體保護電弧銲及52M鎳基填料進行多道次對接銲接。探討不同後熱處理條件及銲件位置對於金相、拉伸強度、衝擊能及破斷面所產生影響。 研究結果顯示銲件不同位置的金相組織差異甚大，銲道靠近界面處產生柱狀晶與細小晶粒交錯的複雜組織。A508低合金鋼熱影響區因Ni, Cr元素擴散關係，有一明顯較軟區域。整個銲件的衝擊性能良好，以SS304L端最優異。衝擊斷面呈韌渦狀的延性破壞特徵。 ;This study discussed mechanical properties and microstructures for dissimilar-metal welding of A508 low-alloy steel and SS304L stainless steel. Multipass butt welded specimens were prepared by gas tungsten arc welding (GTAW) method with 52M Ni-based filler material. The effects of different post-weld heat treatment processes and locations of weldment on the microstructure, tensile strength, impact energy and fracture mechanism were evaluated. The results showed that the variations of microstructures across the weld were large. Columnar grains mixed with fine grains occurred at the interfacial side of the weld. There is a relative soft area in the heat-affected zone of A508 low-alloy steel due to the diffusion of Ni and Cr elements. In general, the impact property of this dissimilar-metal weldment was excellent and many dimples appeared on the fracture surface.