Failure Analysis of a 304 Stainless Steel Flange

Abstract

An investigation for the cracking mechanism of a 304 stainless steel flange was carried out. The flange was installed in a (NH4)2SO4 tank . Optical microscopy examination shows that the cracking is intergrainular. SEM examination shows that the brittle nature of the cracked surface morphology. EDS analysis shows that chloride exists on the cracked surface. Electrolytic etching of the stainless steel in oxalic acid solution reveals that it has intergrainular corrosion sensitivity. The results show that poor welding operation caused to form defects in the weld. Corrosion occurred preferentially in the defect area and cracks propagated circumferentially in the weld seam. The crack propagation direction changed at a point where there was a large circumferential stress.