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在压力29 MPa、不同焊接温度和焊接时间下,采用扩散焊技术连接7075铝合金和AZ31B镁合金。对样品界面进行扫描电镜观察、剪切测试和显微硬度测试来研究焊接温度和焊接时间对可焊性的影响。结果表明:7075铝合金/AZ31B镁合金复合板材被很好地连接在一起,且在焊合区形成金属间化合物如Al_(12)Mg_(17)和Al_3Mg_2。由于晶粒粗化和脆性化合物的形成,升高焊接温度和延长焊接时间会导致剪切强度降低和界面焊接硬度增加。在450°C焊接120 min得到的扩焊接接头具有最小的剪切强度(15 MPa)和最大的显微硬度(HV 176)。提高焊接温度且选择合适的焊接时间能显著地提高焊接界面层厚度。将焊接温度从430°C提高到450°C,焊接时间为120 min时,焊接界面层厚度增加了26%,而当焊接时间为60 min时,界面层厚度增加了6%。
Under the conditions of pressure 29 MPa, different welding temperature and welding time, 7075 aluminum alloy and AZ31B magnesium alloy were connected by diffusion welding technology. Scanning electron microscope (SEM) observation, shear test and microhardness test were performed on the sample interface to study the influence of soldering temperature and soldering time on solderability. The results show that the 7075 aluminum alloy / AZ31B magnesium alloy composite plate is well connected, and the formation of intermetallic compounds such as Al 12 Mg 17 and Al 3 Mg 2 in the welding zone. Due to the coarsening of grains and the formation of brittle compounds, increasing the welding temperature and prolonging the welding time leads to a decrease in the shear strength and an increase in the interfacial welding hardness. Welded joints welded at 450 ° C for 120 min have minimum shear strength (15 MPa) and maximum microhardness (HV 176). Increasing the welding temperature and choosing the proper welding time can significantly improve the thickness of the welding interface layer. When the welding temperature was increased from 430 ° C to 450 ° C, the thickness of the welding interface layer increased by 26% when the welding time was 120 min, and the thickness of the interface layer increased by 6% when the welding time was 60 min.