摘要
高质量的激光电弧复合焊接接头,其焊缝横截面几何形状存在一定差异。为了研究这些差异性,采用焊缝背宽比(Rw)来定量表征焊缝横截面几何形状。基于3 mm厚7050–T7451高强铝合金激光电弧复合焊接优化工艺试验,选取3条典型焊缝,研究了不同Rw与焊接接头宏观成形、微观组织、显微硬度以及拉伸性能的相关性。结果表明,当Rw超过一定阈值时,其正反面熔宽更加均匀,气孔缺陷也得到有效控制。焊缝区的微观组织特征为熔合区附近的细晶层组织、焊缝区大范围的等轴晶组织以及二者之间的柱状树枝晶组织。随着Rw的增加,柱状树枝晶区的宽度逐渐缩小直至消失;焊缝中心平均晶粒尺寸逐渐增大;焊接接头的拉伸性能呈现出先增长后下降的趋势。当Rw≈0.70时,其拉伸性能趋于最佳,平均抗拉强度达到390 MPa,平均断后伸长率约2.9%。拉伸断口呈现出以脆性断裂为主的混合断裂特征。
The high quality joints fabricated by laser arc hybrid welding have certain differences in the crosssectional geometry of the weld seam.In order to study these differences quantitatively,the back width to surface width ratio(Rw)was proposed.Based on the optimization experiments of 7050–T7451 high-strength aluminum alloy with 3 mm thickness by laser arc hybrid welding,three typical welded seams were selected to investigate the correlation effect of different Rw on the macroscopic formation,microstructure,microhardness and tensile properties of the joints.The results show that,only when the Rw exceeds a certain threshold,the weld width on both sides becomes more uniform,and porosity defects are effectively controlled.The microstructure characteristics of the weld zone from the fusion zone to the center of the weld are fine grains layer,columnar dendritic and large-scale equiaxed grains,respectively.With the Rw increasing,the width of the columnar dendritic structure gradually decreases until it disappears,while,the average grain size at the center of the weld seam gradually increases,and the tensile properties of welded joints increase firstly and then decrease.When the Rw is about 0.70,the tensile properties reach the best,with an average ultimate tensile strength of 390 MPa and elongation after fracture of 2.9%.The tensile fractures present a mixed fracture characteristic dominated by brittle fracture.
作者
许飞
高文强
刘斌
雷鹏程
闫晓锋
XU Fei;GAO Wenqiang;LIU Bin;LEI Pengcheng;YAN Xiaofeng(AVIC Manufacturing Technology Institute,Beijing 100024,China;AVIC Qing’an Group Co.,Ltd,Xi’an 710077,China)
出处
《航空制造技术》
北大核心
2025年第9期30-37,76,共9页
Aeronautical Manufacturing Technology
