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焊后热处理的主要目的有 2个 :其一是消除焊接残余应力 ;其二是改善焊接接头的性能 ,因此焊后热处理的评定也应同时考虑这 2个方面。局部焊后热处理通常用于炉内整体热处理无法应用的场合。然而至今各国关于局部焊后热处理的评定标准仍存在很大的差异。采用考虑高温蠕变的粘弹塑性有限元等数值方法与试验相结合 ,对具有初始焊接残余应力的管子在不同热处理条件下进行了系列分析 ,特别是对于局部焊后热处理加热宽度的确定进行了大量研究。基于上述研究提出了 2个局部焊后热处理的评定准则 ,即基于残余应力消除效果的残余应力准则和基于改善焊接接头性能的均热区温差准则。局部焊后热处理应同时满足这两个准则的条件。
The main purpose of post-weld heat treatment are two: one is to eliminate welding residual stress; the other is to improve the performance of welded joints, so the post-weld heat treatment assessment should also consider these two aspects. Local post-weld heat treatment is usually used in the overall furnace heat treatment can not be applied to the occasion. However, there is still a big difference in the assessment standards of local post-weld heat treatment so far. The viscoelasto-plastic finite element method considering the high temperature creep and other numerical methods are combined with the experiments to analyze the pipe with initial welding residual stress under different heat treatment conditions, especially for the determination of the heating width of the local post-weld heat treatment Researching widely. Based on the above studies, two evaluation criteria of post-weld heat treatment are proposed, that is, the residual stress criterion based on the effect of residual stress elimination and the temperature difference criterion of soaking zone based on the performance of welded joints. Local welding heat treatment should meet the conditions of these two criteria.