銲接參數對不□鋼變形與殘留應力之影響

Abstract

本研究目的在探討銲接參數對不□鋼銲件變形與殘留應力之影響。在實驗上，實驗材料選用SUS 304與SUS 310兩種沃斯田鐵型不□鋼，銲接方法採用自生氣護鎢極電弧銲，以肥粒相測定儀來量測304不□鋼銲道之肥粒相含量，以平均垂直位移法來量測銲件之角變形，以鑽孔應變計法來量測銲件之殘留應力。為分析銲接熱應力的作用行為與觀察銲接溫度的變化模式，銲接過程中，在銲件的不同位置處分別以熱電偶來記錄其熱循環數據。實驗結果顯示：1.較高的脈衝頻率，將會提高銲道深寬比與減小熱影響區寬度，進而降低不□鋼銲接角變形與殘留應力；2.較大的脈衝間距，將會減小峰值電流所形成之銲珠重疊區，進而降低不□鋼銲接角變形與殘留應力；3.較高的振幅比，將會降低銲件的溫差，進而降低不□鋼銲接角變形與殘留應力；4.較高的持續時間比，將會降低銲件的熱循環峰值溫度，進而降低不□鋼銲接角變形與殘留應力；5.在保護氣體中添加少許的氮氣含量時，將會導致304不□鋼銲道肥粒相含量的降低；6.保護氣體中之氮氣含量比例愈高時，將會提高銲接熱輸入量，進而提高不□鋼銲接角變形與殘留應力。

This study was aimed at the investigation of the effect of welding parameters on distortion and residual stress of stainless steel. Welding was conducted using the autogenous gas tungusten arc welding and SUS 304 and 310 austenitic stainless steel were used. The ferrite content of 304 stainless steel was measured by ferrite scope. The Mean Vertical-Displacement Method is utilized to measure the distortion. The blind hole drilling technology is employed to determine the residual stress. The thermal cycle of different locations in weldment were recorded by thermocouple. The experimental results show that: 1. The aspect ratio of weld bead can be increased and the width of HAZ can be reduced with the addition of increasing pulsed frequency. 2. Double fusion zone can be decreased with addition of larger pulsed spacing. 3.Temperature difference can be decreased with addition of more amplitude ratio. 4.Peak temperature of thermal cycle can be decreased with addition of more duration ratio. 5. The ferrite content of 304 stainless steel weld was decrease according to the amount of nitrogen added to shielding gas. 6. Heat input during welding can be increased with the addition of adding nitrogen in shielding gas, therefore, the angular distortion and residual stress of stainless steel were increased.