Pang Qiu, Zhao Man, Hu Zhi-Li
Department of Mechanical and Electrical Engineering, Wuhan Donghu University, Wuhan 430212, China.
Hubei Key Laboratory of Advanced Technology for Automotive Components, Wuhan University of Technology, Wuhan 430070, China.
Materials (Basel). 2022 Mar 16;15(6):2157. doi: 10.3390/ma15062157.
Friction stir welding (FSW) of aluminum alloys is an advanced manufacturing technology to realize lightweight bodywork. However, most studies only focus on the mechanical properties and corrosion behaviors of the welded joints. The effect of deformation on the corrosion behavior of FSWed joints is unclear. In this work, the plastic deformation behavior was characterized using uniaxial tensile tests. The effect of deformation on the corrosion behavior of a 2024 aluminum alloy nugget was studied by using a Tafel polarization curve, electrochemical impedance spectroscopy, exfoliation corrosion test, scanning electron microscopy and energy dispersive spectrometer, and transmission electron microscopy. The results show that the corrosion resistance of FSWed joints with different deformation degrees can be ranked as: 0% > 7% > 10% > 4%, and an “inflection point” appears at 7%. The corrosion potential and current density at 7% are near the values at 0%, and the 7% sample shows less corrosion rate than all other deformation samples. Only pitting and bubbling occur in the sample in 96 h. With an increase in plastic deformation, the dislocations and dislocation rings increase, there is an increase in the surrounding winding precipitates. The impurity phase is cleaved by dislocations; a reduction in the size of the impurity phase with low chemical activity can be observed, resulting in an increase in corrosion resistance. However, the transgranular and intergranular cracks appear on the 10% deformation sample. They almost always develop along the grain boundaries after initiation, making them more susceptible to corrosion.
铝合金搅拌摩擦焊（FSW）是实现车身轻量化的先进制造技术。然而，大多数研究仅关注焊接接头的力学性能和腐蚀行为。变形对搅拌摩擦焊接头腐蚀行为的影响尚不清楚。在本工作中，通过单轴拉伸试验表征了塑性变形行为。利用塔菲尔极化曲线、电化学阻抗谱、剥落腐蚀试验、扫描电子显微镜和能谱仪以及透射电子显微镜研究了变形对2024铝合金搅拌摩擦焊焊核腐蚀行为的影响。结果表明，不同变形程度的搅拌摩擦焊接头的耐蚀性排序为：0%＞7%＞10%＞4%，在7%处出现“拐点”。7%时的腐蚀电位和电流密度接近0%时的值，7%的样品腐蚀速率低于所有其他变形样品。在96小时内，样品中仅出现点蚀和气泡。随着塑性变形的增加，位错和位错环增多，周围缠绕的析出物增加。杂质相被位错切断；可以观察到化学活性低的杂质相尺寸减小，从而导致耐蚀性提高。然而，10%变形的样品出现穿晶和沿晶裂纹。它们在萌生后几乎总是沿晶界扩展，使其更易腐蚀。
