In order to avoid the occurrence of small pipe explosion accident outside the furnace,the cracking of dissimilar material welded joint of P91 material outside the machine pipe was taken as an example.The reasons for the cracking were analyzed through macroscopic examination,spectral analysis,fracture analysis,metallographic examination,hardness test and pipe stress analysis.The results showed that the failure mechanism of dissimilar material welded joint of sampling tube was the stress corrosion cracking,and it had the morphology of brittle fracture along the grain boundary.The rainwater flowed on the surface of tube due to the loose insulation layer,which formed the corrosion environment.The secondary stress at the position of fillet weld seriously exceeded the standard,which was the main external factor to cause joint crack-ing.The hardness of tube also severely exceeded the limit.Moreover,the abnormal structure,lack of post-weld heat treat-ment in joint,and high brittleness of heat affected zone were main internal factors to cause joint cracking.
NETL
NSTL
万方数据
维普
