双轴肩搅拌摩擦焊对6061-T6铝合金表面组织及其在3.5%NaCl中腐蚀行为的影响

发布时间：2018-09-03 19:28

【摘要】：采用双轴肩搅拌摩擦焊(BTFSW)技术对7.8 mm厚6061-T6铝合金进行了焊接,对焊接接头各部分的微观组织和截面显微硬度进行了分析,并对母材和焊核在3.5%Na Cl溶液中的腐蚀电化学行为和腐蚀产物膜进行了研究.结果表明,BTFSW后焊缝表面质量良好,热-机影响区晶粒发生再结晶和塑性变形,部分再结晶晶粒发生了伸长和弯曲;热影响区的部分晶粒在热循环的作用下发生粗化,焊核呈细小的等轴晶组织;焊接接头中前进侧热-机影响区硬度最低;在3.5%Na Cl溶液中,6061-T6铝合金的极化曲线表现为阳极溶解和点蚀,母材和焊核区的电化学阻抗谱均由容抗弧和感抗弧组成,BTFSW后6061铝合金的腐蚀电流降低;浸泡480 h后,呈疖状腐蚀的特征,腐蚀产物为Al(OH)3和Al2O3.BTFSW可提高6061-T6铝合金的耐蚀性.
[Abstract]:The (BTFSW) technology of double shaft shoulder friction stir welding was used to weld 7.8 mm thick 6061-T6 aluminum alloy. The microstructure and cross section microhardness of each part of welded joint were analyzed. The corrosion electrochemical behavior and corrosion product film of base metal and nugget in 3.5%Na Cl solution were studied. The results show that after BTFSW, the weld surface quality is good, recrystallization and plastic deformation occur in the thermo-mechanical affected zone, elongation and bending of some recrystallized grains occur, and some grains in the heat-affected zone are coarsened under the action of thermal cycling. The nugget shows fine equiaxed structure, the hardness of the forward side of the welding joint is the lowest, and the polarization curve of 6061-T6 aluminum alloy in 3.5%Na Cl solution shows anodic dissolution and pitting corrosion. The electrochemical impedance spectra of base metal and nugget zone are composed of capacitive and inductive arc, the corrosion current of 6061 aluminum alloy decreases after immersion for 480h, and the corrosion products Al (OH) _ 3 and Al2O3.BTFSW can improve the corrosion resistance of 6061-T6 aluminum alloy.
【作者单位】：江苏科技大学材料科学与工程学院;河海大学机电工程学院;
【基金】：国家自然科学基金项目51401092和51575252以及51205175 江苏科技大学博士基金资助~~
【分类号】：TG453.9;TG146.21

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