环境条件对轨道车辆用不锈钢激光焊接接头疲劳强度的影响  

Effect of Environmental Condition on Fatigue Strength of Laser Welded Joint of Stainless Steel for Rail Vehicles

作　　者：李浩哲 韩晓辉 杨志斌 史春元[1] LI Haozhe;HAN Xiaohui;YANG Zhibin;SHI Chunyuan(School of Maerials Science and Engineering,Dalian Jiaotong University,Dalian 116028,China;CRRC Sifang Co.,Ltd.,Qingdao 266111,China)

机构地区：[1]大连交通大学材料科学与工程学院,辽宁大连116028 [2]中车青岛四方机车车辆股份有限公司,山东青岛266111

出　　处：《热加工工艺》2020年第21期39-42,46,共5页Hot Working Technology

摘　　要：采用成组法和升降法,对板厚0.8 mm的SUS301L-DLT与板厚2 mm的EN1.4318+2G轨道车辆用不锈钢激光搭接焊接头分别在室温空气环境、-40℃低温空气环境和3.5%NaCl水溶液环境中进行剪切拉伸疲劳试验,绘制S-N曲线并进行断口形貌分析。试验结果表明:在循环寿命为1×107条件下,与空气环境相比,-40℃低温环境下不锈钢激光搭接焊接头的剪切拉伸疲劳强度提高57.8%,而在3.5%NaCl水溶液中接头疲劳强度降低25.5%。激光焊接头的疲劳裂纹均起始于搭接下板内侧靠近焊缝应力集中处,沿下板厚度方向扩展直至断裂,其中在瞬时断裂区存在大量韧窝,呈韧性断裂特征。By grouping and lifting method, the shear tensile fatigue tests of laser lap welded joint of 0.8 mm thick SUS301L-DLT and 2 mm thick EN1.4318 + 2G rail stainless steel for rail vehicle were carried out in room temperature environment,-40 ℃ low temperature air environment and 3.5% NaCl aqueous solution respectively, the S-N curve was drawn and fracture morphology was analyzed. Experimental results show that under the condition of the cycle life of 1×10~7,compared with that of the air environment, shear tensile fatigue strength of stainless steel laser lap welded joint increases by 57.8% in-40 ℃ low temperature environment, while the fatigue strength of the welded joint decreases by 25.5% in 3.5%NaCl aqueous solution. Fatigue cracks of laser welded joints all start from the inner side of lapped lower sheet closed to the stress concentration of weld seam, and extend along the thickness direction of the lower sheet until the sheet fractures. There are a large number of dimples in the instantaneous fracture zone, showing the characteristics of ductile fracture.

关 键 词：轨道车辆 不锈钢 激光焊 环境条件 疲劳强度 

分 类 号：TG405[金属学及工艺—焊接] TG456.7