某电厂水冷壁管氢致应力腐蚀泄漏原因分析

Analysis of Hydrogen-induced Stress Corrosion Leakage in Water Cooling Wall of a Power Plant

某电厂一台超临界锅炉水冷壁管在检修中发现3处穿透裂纹，裂纹位于水冷壁管排安装拼接焊缝附近。水冷壁管常见泄漏原因包括超温、腐蚀减薄和磨损减薄等。通过DR、金相和电镜等方法分析了该水冷壁管的开裂原因，发现氢致应力腐蚀是管壁泄漏的原因，氢致应力腐蚀使材料在没有发生明显变形减薄的情况下发生低应力脆性开裂，开裂前无征兆，危害很大。

Three penetrating cracks are found in the water wall tubes of a power plant supercritical boiler during maintenance,the crack is located near the water cooling wall tubes welding seam.The common leakage causes of water wall tube include overtemperature,corrosion reduction and wear reduction etc.In this paper,the reason of the leakage of the water cooling wall tube is found by means of DR,metallography,electron microscopy etc.The stress corrosion of hydrogen causes the material to occur low stress brittle cracking without obvious deformation and thinning.This form of cracking has no earlier signs and is very harmful.