焊接残余应力在循环拉伸载荷作用下演变规律

摘要

采用便携式iXRD残余应力仪测量6 mm厚A6005-T6铝合金平板试样焊接后的残余应力,利用PWS-100低频疲劳试验机对平板试样进行低周次的循环加载,采用QBG-100高频疲劳试验机,试验频率100 Hz,进行3个阶段的加载,测出不同加载方式下的应变量.结果表明:在低周次的动态循环载荷下,1～4号应变片总应变演变趋势为第1次循环加载后,1～4号应变片的总应变均有变化,为正值,在第2次到10000次的循环范围内,随着循环加载次数的增加,1～4号应变片的总应变未随着循环次数的变化而变化.在高周次的循环加载中,加载次数从1万次到1 000万次,1～4号应变片的总应变量基本保持不变,即在1×10～1×107循环加载过程中,材料未再产生新的塑性变形,说明焊接残余应力未随着循环次数的增加而继续发生松弛.%Low cycle loading testing method with the PWS-100 low frequency fatigue machine and high cycle loading testing method with the QBG-100 high frequency fatigue machine were used to test the A6605-T6 aluminum alloy welded joints.The dynamic strain test machine was used to test the strain value of the above two fatigue method.The results showed that the strain value of No.1～4 all changed after the first time loading under the low cycle loading method but the strain value didn't change after second time loading to 10 million times loading.With the cycle times have changed from 10 thousand times to 10 million times,the strain value of N0.1～4 didn't change.So the results showed that the welded joints didn't show new plastic deformation with the increase of the cycle times,so the welding residual stress didn't continue to relax with the incrrease of the cycle times.