Abstract: During the bending test for welding process evaluation of a certain S460M steel pipe, the bending specimen fractured. Chemical composition analysis, mechanical performance testing, metallographic examination, scanning electron microscopy, and energy spectrum analysis were used to analyze the cause of fracture in bending specimens. The results show that there was martensite in the weld seam and heat affected zone of the fractured specimen, and there were a large number of non-metallic inclusions near the fracture surface, which damaged the continuity of the metal matrix. Under the action of bending force, the specimen underwent brittle fracture.