本研究使用A508低合金鋼與316L不銹鋼為母材，填料對接、緩衝層及覆銲層製作使用鎳基182合金、82合金和52M合金作為熔填金屬，透過GTAW及SMAW銲接技術，採用Temper bead之銲接方式完成銲接作業。透過銲接參數及程序之設定，檢視銲接區域之微觀變化，最後使用X-ray檢測銲接區域之軸向殘留應力，探討異質銲接件經覆銲前、後殘留應力值變化。
實驗結果顯示，A508母材熱傳導速度快熱膨脹係數小，可以快速舒緩及平衡銲接時造成的局部熱應力；182合金和316L母材則易因熱傳導速度慢熱膨脹係數大而產生局部高溫造成熱量累積，冷卻後產生嚴重的拉扯，增加殘留應力。覆銲層施作時的熱影響，皆可使銲件厚度中心以上產生明顯的壓應力。異質介面處主要因熱膨脹係數差異造成相互拉扯，而產生應力疊加或抵消，若界面間熱傳導及熱膨脹係數差異愈大，產生殘留應力變化量將更加顯著。

This research involved weldment of dissimilar A508 low alloy steel and 316L stainless steel for base metal. The welding of dissimilar parts was conducted by use of gas tungsten arc welding (GTAW) and gas metal arc-welding (GMAW) techniques with nickel-based 82/182 alloys used as filler metal for butt joint and butter layer while inconel alloy 52M used for cladding. Observation of microstructure changes within the weldment and its were conducted for different settings of welding parameters and processes. The X-ray diffraction method was used to detect and analyze the axial residual stress on the dissimilar metal weld area and on the cladding layer of the weldment .
Experimental results showed that thermal stress was generated during cooling of weldment due low thermal expansion coefficient of A508 base metal and high thermal expansion coefficient of 182 alloy and 316L base metal. Residual stresses therefore increased after cooling of welding due to presence of both compressive and tensile stresses. The thermal influence of the cladding layer can also significantly increase compressive stress at the weldment. The interface of the dissimilar metal weldment experienced tensile stresses due to difference in thermal expansion coefficient, and the residual stress. Thus, residual stress would increase further with increased difference of thermal expansion coefficients.

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