铝合金与镁、铜焊接工艺及接头组织和性能研究
发布时间：2018-11-02 19:52
【摘要】：铝/镁、铝/铜复合构件因其性能互补优势在诸多工业领域具有广泛的应用前景,然而由于异种金属物理、化学和物理冶金性能的差异,难以获得力学性能可靠和耐腐蚀性良好的焊接接头,异种金属焊接工艺制约了这类结构件的发展。本文首先在50～100A电流条件下对5052铝合金/AZ31B镁合金进行交流TIG焊接,在优化焊接电流参数的基础上,研究焊丝材料对接头组织和力学性能的影响;其次采用固相扩散焊和瞬间液相扩散焊对5052铝合金/铜进行连接,研究焊接温度和保温时间对接头界面扩散层厚度、显微组织和力学性能的影响;最后对这两种异种金属焊接接头在3.5%NaCl溶液中进行浸泡腐蚀和极化曲线测试,研究接头的耐蚀性。对于铝合金/镁合金交流TIG焊,在焊接电流为75～80A、焊接速度为350mm/min的条件下,可获得焊缝成形良好的焊接接头。焊丝材料显著影响焊缝的组织组成和接头的抗拉强度。与不填充焊丝的焊缝相比,填充AZ31B镁合金焊丝的焊缝中析出大量细小的颗粒状α-Mg初生相,(α-Mg+Mg_(17)Al_(12))共晶体量减少,接头强度为20MPa,提高了25%;填充5052铝合金焊丝后,Mg_(17)Al_(12)初生相由胞状晶转变为树枝晶,且(α-Mg+Mg_(17)Al_(12))共晶体量显著减少,接头强度为5MPa,降低了 69%。固相扩散焊和瞬间液相扩散焊均可实现铝合金/铜的有效连接,得到完整的焊接接头。在480℃、120min条件下得到的固相扩散焊接头组织呈层状分布,从铝侧至侧铜依次为Al2Cu、Cu_(12)Al_9和Cu9A14,硬度值依次为264HV、170HV和138HV。随着温度升高和保温时间延长,Cu9A14和Al2Cu化合物层厚度显著增加。在570℃、20min条件下得到的瞬间液相扩散焊接头组织致密,接头界面反应区包括宽大的(α-Al+Al2Cu)共晶体区和由Cu_9Al_4、Cu_(12)Al_9和Al2Cu组成的化合物区。随着保温时间的延长,共晶体区的宽度显著增加,且共晶组织的形貌由层片状转变为棒状和菊花状。浸泡腐蚀实验表明,铝合金/镁合金TIG焊接头的焊缝区和母材区呈现不同的耐蚀性,焊缝区的耐蚀性最好,铝母材的次之,邻近焊缝的镁母材的最差。极化曲线分析表明,填充不同焊丝焊缝区的耐蚀性也有差异,镁焊丝焊缝的耐蚀性最好,无焊丝的次之,铝焊丝的最差。铝合金/铜的固相扩散焊接头的耐蚀性优于瞬间液相扩散焊接头,瞬间液相扩散焊接头界面结合区的中间区域的耐蚀性明显优于靠近两侧母材区域的耐蚀性。
[Abstract]:Aluminum / magnesium, aluminum / copper composite components have a wide application prospect in many industrial fields because of their complementary advantages. However, due to the differences in physical, chemical and physical metallurgical properties of dissimilar metals, It is difficult to obtain welded joints with reliable mechanical properties and good corrosion resistance. Dissimilar metal welding technology restricts the development of this kind of structural parts. In this paper, the AC TIG welding of 5052 aluminum alloy / AZ31B magnesium alloy was carried out at 50 ~ 100A current. Based on the optimization of welding current parameters, the effect of welding wire material on the microstructure and mechanical properties of the joint was studied. Secondly, 5052 aluminum alloy / copper was joined by solid phase diffusion welding and transient liquid phase diffusion welding, and the effects of welding temperature and holding time on the thickness, microstructure and mechanical properties of the interface diffusion layer were studied. Finally, the corrosion and polarization curves of the two dissimilar metal welded joints were tested in 3.5%NaCl solution to study the corrosion resistance of the joints. For the AC TIG welding of aluminum alloy / magnesium alloy, the well-formed welding joint can be obtained when the welding current is 75 ~ 80A and the welding speed is 350mm/min. The wire material significantly affects the microstructure of the weld and the tensile strength of the joint. Compared with the weld without filler wire, a large number of fine grained 伪-Mg primary phases were precipitated in the weld of AZ31B magnesium alloy filler wire, the eutectic amount of (伪-Mg Mg_ (17) Al_ (12) was reduced, and the joint strength was 20 MPA, which increased 25%. After filling 5052 aluminum alloy wire, the primary phase of Mg_ (17) Al_ (12) changed from cellular crystal to dendrite, and (伪 Mg Mg_ (17) Al_ (12) eutectic volume decreased significantly, and the joint strength was 5 MPA, which decreased 69%. Solid phase diffusion welding and transient liquid phase diffusion welding can realize the effective connection of aluminum alloy / copper and obtain the complete welding joint. The microstructure of the solids diffusion welded joints was layered at 480 鈩，
本文编号：2306793
[Abstract]:Aluminum / magnesium, aluminum / copper composite components have a wide application prospect in many industrial fields because of their complementary advantages. However, due to the differences in physical, chemical and physical metallurgical properties of dissimilar metals, It is difficult to obtain welded joints with reliable mechanical properties and good corrosion resistance. Dissimilar metal welding technology restricts the development of this kind of structural parts. In this paper, the AC TIG welding of 5052 aluminum alloy / AZ31B magnesium alloy was carried out at 50 ~ 100A current. Based on the optimization of welding current parameters, the effect of welding wire material on the microstructure and mechanical properties of the joint was studied. Secondly, 5052 aluminum alloy / copper was joined by solid phase diffusion welding and transient liquid phase diffusion welding, and the effects of welding temperature and holding time on the thickness, microstructure and mechanical properties of the interface diffusion layer were studied. Finally, the corrosion and polarization curves of the two dissimilar metal welded joints were tested in 3.5%NaCl solution to study the corrosion resistance of the joints. For the AC TIG welding of aluminum alloy / magnesium alloy, the well-formed welding joint can be obtained when the welding current is 75 ~ 80A and the welding speed is 350mm/min. The wire material significantly affects the microstructure of the weld and the tensile strength of the joint. Compared with the weld without filler wire, a large number of fine grained 伪-Mg primary phases were precipitated in the weld of AZ31B magnesium alloy filler wire, the eutectic amount of (伪-Mg Mg_ (17) Al_ (12) was reduced, and the joint strength was 20 MPA, which increased 25%. After filling 5052 aluminum alloy wire, the primary phase of Mg_ (17) Al_ (12) changed from cellular crystal to dendrite, and (伪 Mg Mg_ (17) Al_ (12) eutectic volume decreased significantly, and the joint strength was 5 MPA, which decreased 69%. Solid phase diffusion welding and transient liquid phase diffusion welding can realize the effective connection of aluminum alloy / copper and obtain the complete welding joint. The microstructure of the solids diffusion welded joints was layered at 480 鈩，
本文编号：2306793
本文链接：https://www.wllwen.com/kejilunwen/jiagonggongyi/2306793.html
