摘要
对材质为TP304H的某2 100.7 t/h锅炉高温再热器U型弯管的爆管样进行了宏观开裂特征检查、金相组织检验、微观裂纹特征及微观断口形貌分析、拉伸性能测试。结果表明:由于TP304H钢无碳化物稳定化元素,在较高温度下运行后晶界大量析出碳化物,造成晶界附近贫Cr区,晶界严重弱化;弯管形变量超过ASME规范对奥氏体材料的冷加工形变量的控制要求,且未进行弯管后的固溶去应力处理。在高温运行状态发生的TP304H钢的晶间腐蚀和弯管内弧存在的较高残余拉应力二者共同作用下,在向火面内弯处形成沿晶开裂裂纹,裂纹由向火面外壁发生,裂纹方向与弯管弯曲环向一致,向内壁沿晶扩展。
The macroscopical and microcosmic cracking character, metallographic examination, fracture appearance and mechanical property on the failure U-type bend TP304H tube which operated on high temperature reheater for about 60 000 hours in the 2 100.7 t/h boiler were tested and evaluated in this paper. As the results show, because the chemical composition of TP304H steel doesn＇t include carbide stabilizing element, when the tubes operate at higher temperature, the strength of grain boundary decreases seriously with the formation of chromium depleted zone; The forming strain of the bend has exceeded ASME standard the post cold-forming strain limits, and the bend should Be relief annealed. With the combination of intercrystalline corrosion that resulted from high temperature operation of TP304H austenitic stainless steel and large residual tensile stress at the bend＇s intrados, the intergranular cracking immerges at the intrados. The intergranular crack originated from the outside of fire-facing tube, consistent with the bend＇s circumference extending toward the tube＇s inside.
出处
《中国电力》
CSCD
北大核心
2006年第6期41-44,共4页
Electric Power
关键词
锅炉管
TP304H钢
冷加工
残余拉应力
晶间腐蚀
沿晶开裂
boiler tubes
TP304H steel
cold working
residual tensile stress
intercrystalline corrosion
intergranular cracking
