换热器管子与管板焊接接头残余应力数值模拟

Numerical simulation of welding residual stress of tube-totubesheet joint in heat exchangers

关键词:  换热器  管子与管板  焊接残余应力  有限元ABAQUS

Key words:  heat exchanger  tube and tubesheet  welding residual stress  finite element ABAQUS

摘要:

利用有限元软件ABAQUS,对换热器管子与管板焊接残余应力进行数值模拟,获得了焊接接头残余应力的分布规律,比较了伸出角接头和内角接头的优劣。计算结果表明,内角接头残余应力比伸出角接头小。最大径向应力出现在管板表面的热影响区,对管板表面裂纹有主要影响。最大环向应力出现在焊缝根部,对管子与管板连接失效影响较大。相邻两换热管之间,由于后面换热管的焊接加热作用,使前面管子焊缝局部应力值下降,有利于降低应力腐蚀开裂的敏感性。研究结果为优化换热器管子与管板的焊接工艺、控制残余应力提供了理论依据。

Abstract:

Using finite element program-ABAQUS, the welding residual stress of tube-to-tubesheet joint in heat exchangers had been numerically simulated.The distribution of welding residual stresswas obtained.A comparison between tube end extended out of tubesheet welded joint and inside hole welded joint wasmade. The welding residual stress of inside hole welded joint is much smaller than that of tube end extended out of tube sheet joint. So using inside hole welded joint can decrease the susceptibility of stress corrosion cracking(SCC).The maximum of radial stress existsin the HAZ outside surface of tubesheet, which has great influence on tubesheet surface cracks.The maximum of hoop stress appears in the weld root, which has great influence on the connection failure between tube and tubesheet.The residual stress of former pipe bead is decreased due to the later pipe welding heating, which is useful for decreasing the susceptibility of SCC.Thiswork provides a theory reference for optimizing the welding procedure and controling the welding residual stress for tube-to-tubesheet joint.