高强钢焊接接头疲劳寿命的提高方法进展

Development on improving fatigue life of high strength steel welded joints

随着人们对装备性能和环保的追求高强钢被越来越多地应用,对于高强钢而言焊接作为一种重要的材料连接方法应用非常广泛,然而接头疲劳性能并不随着钢材强度升高而提高,因此提高焊接接头的疲劳寿命对于高强钢的应用具有重要意义.基于近年来国内外相关研究,总结了影响高强钢焊接接头疲劳性能的因素,包括应力集中、焊接残余应力、焊接方法和焊材选择等因素.综述了多种提高高强钢焊接接头疲劳寿命的方法,根据其对接头疲劳性能改善机理进行分类,第1类方法主要基于对焊缝几何形貌的改进,通过降低应力集中系数减缓疲劳裂纹的萌生提高寿命.如TIG熔修、激光熔修、喷涂沉积和仿形加工和打磨等方法.其中一些方法在改进焊缝几何形貌的同时还引入对疲劳寿命有益的残余压应力.第2类寿命提高方法主要基于对焊缝残余应力进行调整,通过减小残余拉应力或引入残余压应力减缓裂纹扩展速度.如焊后热处理(postweld heat treatment,PWHT)、高频机械冲击(high frequency mechanical impact,HFMI)、激光冲击强化(laser shock processing,LSP)、滚压和搅拌摩擦等方法,其中一些方法同时还会改善接头表面硬度和晶粒尺寸从而影响疲劳裂纹萌生.并对这些方法的使用提出建议和展望.

With the increasing application of high-strength steel in people's pursuit of equipment performance and environmental protectio,welding,as an important material joining method,is essential in the application of high-strength steel.However,the fatigue performance of welded joints does not improve with the increase of steel strength level.So how to improve the fatigue life of the welded joints is of great significance to the application of high-strength steel.Based on the relevant research results at home and abroad in recent years,this paper summarizes the factors affecting the fatigue performance of high-strength steel welded joints,including stress concentration,welding residual stress,welding method and welding material.A variety of methods to improve the fatigue life of high strength steel welded joints are reviewed,and they are classified according to the mechanism of improving the fatigue performance of joints.The first type of life improvement method is mainly based on the improvement of the geometric morphology of the joint,and the life is improved by reducing the stress concentration factor to slow down the initiation of fatigue cracks,such as TIG dressing,laser dressing,spray deposition,profiling and grinding methods.Some of these methods improve the weld morphology and lead-in residual compressive stress that is beneficial to fatigue life.The second type of life improvement method is mainly based on the adjustment of the residual stress of the joint.The crack growth rate is slowed down by reducing the residual tensile stress or introducing the residual compressive stress,such as post-weld heat treatment(PWHT),high frequency mechanical shock(HFMI),laser shock processing(LSP),rolling and friction stir.Some of which also improve the surface hardness and grain size of the joint to affect the fatigue crack initiation.Suggestions and prospects for the use of these methods are put forward.