载荷作用下5A06铝合金焊接试样的腐蚀敏感性

Corrosion sensitivity of 5A06 aluminum alloy welded samples under loading

针对5A06铝合金焊接对腐蚀敏感性的影响,研究了载荷作用下的不同焊缝方向(垂直、穿越)的5A06铝合金试样在50℃的3.5%Na Cl溶液中的腐蚀行为的影响和焊接接头的电化学腐蚀行为。结果表明,经过110 d的盐水溶液浸泡后,2种焊缝试样均是热影响区首先发生腐蚀,表面的腐蚀坑两侧由于材料组织的不同分别呈台阶式和韧窝状。穿越焊缝试样应力腐蚀敏感性较低,腐蚀坑顶端应力集中,有滑移台阶;垂直焊缝试样应力腐蚀敏感性较高,腐蚀坑沿焊缝贯穿试样表面,腐蚀坑两侧呈平行撕裂状态。电化学极化曲线表明,热影响区、母材区和焊缝区的自腐蚀电位分别为-1.369、-0.791和-0.740 V。

Aimed at the aluminum alloy welding effect on corrosion sensitivity,we have applied loading on the 5 A06 aluminum alloy with the welds in different directions（vertical,cross） and studied the effects of stress loading on the corrosion behavior of the alloy in 3. 5% Na Cl solution at 50℃ and the electrochemical corrosion behavior of the welded joints. The results show that after being soaked for 110 days in brine solution,heat-affected zone is firstly corroded and both sides of the corrosion pits on the surface exhibited step and dimple features respectively,because of the different material structure. The stress corrosion sensitivity of the cross weld specimen is relatively low and the stress concentration exists at the corrosion pit tip with a sliding step. Vertical weld specimen has higher sensitivity to stress corrosion with the corrosion pits across the surface along the weld. Both sides of the corrosion pits on the vertical weld specimen tear parallelly. The electrochemical polarization curves indicate that the corrosion potential of the heat-affected zone,base-metal zone and weld zone are-1. 369 V,-0. 791 V and-0. 740 V,respectively.