灭菌器组合工艺焊接残余应力的消除与评价

Elimination and evaluation of welding residual stress in sterilizers welded by combined process

针对国产脉动真空灭菌器内腔焊缝处多次开裂现象，围绕焊接残余应力及消除方法进行了系列研究．根据市场上灭菌器异种钢间断角焊缝特征设计了7种组合结构焊板，应用X射线法定量给出了残余应力分布规律，并对用焊后浇水速冷处理工艺消除残余应力的尝试进行了试验验证．结果表明，各种焊板残余应力均达到屈服应力，由此引起的应力腐蚀与腐蚀疲劳是灭菌器内腔开裂的直接原因；二氧化碳焊接工艺残余应力较焊条电弧焊高10％～22％，残余应力与加强筋类型基本无关；浇水速冷处理工艺可有效降低表面残余应力，降幅达50％～70％，提高疲劳极限12％-14％．有效降低焊接残余应力是解决内腔开裂的重要途径．

Observing that cracks appear simultaneously on multi-location near weld on intracavity of domestic vacuum,we investigate a series of studies on welding residual stress and its corresponding elimination methods.We design seven types of combined-structure plates and quantitatively measure the residual stress distribution by X-ray method based on the characteristics of discontinuous welding of different steel in sterilizers.The results show that welding residual stress of all seven types of boards reaches yield stress and causes the stress corrosion and corrosion fatigue which are main reasons of the intracavity cracking of sterilizers.In addition,residual stress resulted from carbon dioxide welding is 10%-22% higher than manual welding,and residual stress is indifferent with rebar type.After experimental verification of post-welding watering quick-cooling technology to eliminate the residual stress,we conclude that watering quickcooling can effectively reduce the surface residual stress by 50%70% and increase fatigue limit by 12%-14% on watering surface.Reducing welding residual stress is an important way to solve the problem of cracking in the intracavity of sterilizers.