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本文用光镜(OLM)、扫描电镜(SEM)分析了一段已服役约210000h 的电厂再热蒸汽管道焊接接头蠕变空洞的分布形态;分析了两种恢复热处理工艺(亚临界温度热处理和正回火热处理)对蠕变空洞形态及其分布的影响.试验结果表明,两种恢复热处理工艺都能减少蠕变空洞的数量,改善蠕变空洞的形态及其分布,使蠕变空洞由原来不规则的形状变成球形,使原来主要分布在晶界处的蠕变空洞部分“迁移”到晶内,从而改善了晶界处的应力状态,提高了蠕变抗力.比较两种恢复热处理工艺对减少蠕变空洞的数量,以及对改善螭变空洞的形态及其分布的作用后发现,正回火工艺优于亚临界温度热处理工艺.
In this paper, OLM and SEM were used to analyze the distribution of creep voids in a welded section of a reheat steam pipe of about 210000h in power plant. Two recovery heat treatment processes (subcritical temperature heat treatment and positive tempering Heat treatment) on the morphology and distribution of creep voids.Experimental results show that the two kinds of recovery heat treatment process can reduce the number of creeping voids and improve the shape and distribution of creep voids, so that the creep voids from the original irregular The shape becomes spherical, so that the original mainly distributed in the grain boundary creep cavity part of the “migration” into the crystal, thereby improving the grain boundary stress state, improve the creep resistance.Comparison of two kinds of recovery heat treatment process to reduce the creep The number of voids and the effect of improving the shape and distribution of voids are found to be superior to subcritical heat treatment.