B1500HS高强度钢与AA5052铝合金自冲铆接成形与力学性能分析

Forming and mechanical properties analysis of self-piercing riveted joints of B1500HS high strength steel and AA5052 aluminum alloy

为研究B1500HS高强度钢与AA5052铝合金自冲铆接力学性能,进行自冲铆接试样准静态拉伸试验与轴向拉-拉疲劳试验。采用最小二乘法对疲劳试验数据进行拟合得到载荷/应力比-寿命曲线,分析了载荷水平和应力比对自冲铆接接头疲劳性能的影响。结果表明:准静态拉伸试样SAT(B1500HS+AA5052)的自冲铆接成形参数优于AST(AA5052+B1500HS)试样成形参数,基板顺序对准静态拉伸最大失效载荷影响较小,但SAT试样失效位移远大于AST试样。在不同载荷水平及应力比下,SAF(B1500HS+AA5052)试样的疲劳性能均优于ASF试样(AA5052+B1500HS)。在取值范围内,两种试样的疲劳寿命随载荷水平的增大而减小,随应力比的增大而增大。SAT试样的准静态拉伸失效形式为B1500HS基板的材料撕裂,AST试样的准静态拉伸失效为铆钉由AA5052铝合金板脱离出来。SAF试样的疲劳失效形式为铝合金板由铆接点单向延伸至基板边缘的断裂,而ASF试样铝合金板产生翼状对称宏观疲劳裂纹。

To study the mechanical properties of B1500HS high strength steel and AA5052 aluminum alloy self-piercing riveted joint,the quasi-static tensile test and axial tension-tension fatigue test of joints were carried out.The load/stress ratio-life curves were obtained by fitting the fatigue test data with the least square method,and the influence of load level and stress ratio on fatigue property of self-piercing riveted joint was analyzed.The results show that forming parameters of quasi-static tensile sample SAT(B1500HS+AA5052)are superior to that of AST sample(AA5052+B1500HS).The influence of substrate order on the maximum failure load is relatively small,while the failure displacement of SAT sample is much greater than that of AST sample.Fatigue properties of fatigue sample SAF(B1500HS+AA5052)with different load levels and stress ratios are all better than those of ASF sample(AA5052+B1500HS).Within the value range,the fatigue life of the two kinds of samples decreases with the increase of load level and increases with the increase of stress ratio.The quasi-static tensile failure form of SAT sample is the material tear of B1500HS substrate,and that of AST sample is the detach of rivet from AA5052 aluminum alloy sheet.The fatigue failure form of SAF sample is the fracture of AA5052 substrate extending unidirectionally from riveting point to the edge of substrate,however,the winglike symmetrical fatigue crack occurs on AA5052 aluminum alloy sheet of ASF sample.