奥氏体不锈钢换热管胀接残余应力分析

Analysis of Residual Stress of Austenitic Stainless Steel Heat Exchange Tube Expansion

换热管与管板的可靠性连接是热交换器安全运行的重要保障。模拟了304不锈钢换热管与16Mn管板焊胀并用结构的内压加载过程,对比了胀接分别采用强度胀和贴胀的残余应力。研究表明,胀接内压小于30 MPa时,强度焊+强度胀结构与强度焊+贴胀结构都处于弹性变形范围,内压卸载后无残余应力。胀接内压在30~40 MPa时,残余应力增加迅速,之后增速变缓。胀接内压在30~175 MPa时,2种结构残余应力相近。胀接内压大于175 MPa时,2种结构残余应力差异逐渐明显,开槽结构残余应力明显大于无槽结构。在胀接压力加载到100 MPa并卸压至0 MPa后,2种结构残余应力分布没有明显差异,开槽对残余应力基本没有影响。

A reliable connection between the heat exchange tube and the tube sheet is an essential guarantee for the safe operation of the heat exchanger.A computational simulation was conducted to assess the internal pressure loading process of a 304 stainless steel heat exchange tube and a 16Mn tube sheet.The residual stress of an expansion joint with strength expansion and expansion was then compared.The results of the research demonstrate that when the internal pressure of the expansion joint is less than 30 MPa,both the strength welding plus strength expansion structure and the strength welding plus expansion structure are within the elastic deformation range.Furthermore,no residual stress is observed after the internal pressure is unloaded.When the internal pressure of the expansion joint is between 30 and 40 MPa,the residual stress increases rapidly,reaching a peak,and then the growth rate slows down.When the internal pressure of the expansion joint is between 30 and 175 MPa,the residual stresses of the two structures are comparable.When the internal pressure exceeds 175 MPa,the residual stress difference between the two structures becomes increasingly apparent,with the residual stress of the slotted structure exhibiting a significantly higher value than that of the non-slotted structure.Following the loading of the expansion pressure to 100 MPa and subsequent unloading to 0 MPa,no discernible difference in the residual stress distribution is observed between the two structures,and the slotting has no effect on the residual stress.