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针对某电厂2210 t/h锅炉末级过热器TP347H奥氏体不锈钢爆管试样进行爆口宏观检验、材质成分分析和金相组织检验。综合测试分析认为,在短时超温运行后,晶界析出大量碳化物,使晶界附近形成贫铬区,晶界严重弱化;管外壁的浅表折叠形成残余应力和粗大晶粒形成了应力集中脆性区域。在高温运行工况下,内壁的晶间腐蚀,外壁应力集中脆性区域承载能力的下降和残余应力三者共同作用下,其韧性、强度和有效承载截面逐步减小,最终在介质内压周向应力作用下导致断裂。
A macro explosion test, material composition analysis and metallographic examination were carried out for the tube burst of TP347H austenitic stainless steel for the 2210 t / h boiler superheater of a power plant. According to the comprehensive test and analysis, a large amount of carbides are precipitated in the grain boundary after short-term over-temperature operation, resulting in the formation of a chromium-depleted region near the grain boundary and severe grain boundary weakening; superficial folding of the outer wall of the tube forms residual stress and coarse grains to form stress Focus on the brittle area. Under high temperature operating conditions, the intergranular corrosion of the inner wall, the decrease of the bearing capacity of the stress concentration brittle zone in the outer wall and the residual stress, the ductility, strength and effective load-bearing cross section are gradually reduced, Rupture under stress.