B950CF钢超窄间隙激光填丝焊接头疲劳性能  

Fatigue properties of B950CF steel ultra-narrow gap laser wire filler welding joint

作　　者：张成竹 王东晔 华程 刘岳 张骞 朱振新 ZHANG Chengzhu;WANG Dongye;HUA Cheng;LIU Yue;ZHANG Qian;ZHU Zhenxin(AVIC Chengdu Aircraft Industrial(Group)Co.,Ltd.,Chengdu,610031,China)

机构地区：[1]航空工业成都飞机工业(集团)有限责任公司,成都610031

出　　处：《焊接学报》2024年第9期94-102,共9页Transactions of The China Welding Institution

摘　　要：超窄间隙激光填丝焊(ultra-narrow gap laser welding,Ultra-NGLW)是一种先进的厚贝氏体钢焊接技术,具有热输入小,焊接接头低应力、变形小等优点.通过对不同“激光填丝-激光打底”比例的Ultra-NGLW接头高频拉-拉疲劳试验,绘制了10 mm厚不同填丝深度Ultra-NGLW接头S-N曲线,并通过对比分析接头的S-N曲线和疲劳断口特征,得到影响UltraNGLW接头疲劳性能的主要原因.试验结果表明,随着激光填丝深度的加深,接头的疲劳性能逐渐降低,填丝深度为0 mm时,接头疲劳强度为337.5 MPa,当填丝深度达到5 mm后,疲劳强度趋于稳定在270 MPa左右,Ultra-NGLW接头的疲劳源主要为焊缝粗晶区和熔合区的气孔、夹杂等焊接缺陷,在高频拉-拉疲劳循环载荷的作用下,粗晶区马氏体脆硬组织中形成较多裂纹,使其疲劳源裂纹快速扩展并连通脆硬组织中的裂纹直至接头失效.Ultra-NGLW is an advanced welding technology for thick bainitic steel,which has the advantages of low heat input,low stress and deformation of welded joints.By conducting high-frequency tensile fatigue tests on Ultra-NGLW joints with different"filling-bottoming"ratios,S-N curves of 10 mm thick Ultra-NGLW joints with different wire filling depths were plotted,and by comparing and analyzing the S-N curve and fatigue fracture characteristics,the main factors affecting the fatigue performance of Ultra-NGLW joints were identified.The experimental results indicate that as the depth of laser wire filling increases,the fatigue performance of the joint gradually decreases.When the filling depth is 0 mm,the fatigue strength of the joint is 337.5 MPa,while the filling depth reaches 5 mm,the fatigue strength tends to stabilize at around 270 MPa.The fatigue source of Ultra-NGLW joints is mainly welding defects such as pores and inclusions in the coarse-grained and fusion zones of the weld.Under the action of highfrequency tensile fatigue cyclic loads,more cracks are formed in the martensitic brittle hard structure in the coarse-grained zone,causing the fatigue source cracks to rapidly expand and connect the cracks in the brittle hard structure until the joint fails.

关 键 词：超窄间隙激光填丝焊 疲劳强度 S-N曲线 疲劳断口 贝氏体高强钢 

分 类 号：TG405[金属学及工艺—焊接]