Abstract: The cause of cold bend induced cracking of submerged arc welding joint of 20G steel was investigated by electron fractography supplemented by optical metallographic study of joints prior to bending.Hot cracking test and thermal plasticity test of 20G steel were also made.It was suggested that there were solidification and liquation micro-cracks in the fusion zone.As the test piece was being cold bent,the micro-cracks propagated.The bend induced crack was thus formed.