A Study of Cracking in Weld Zone of 50kg/mm² Class High Tensile Steels

Abstract

To clarify the types of cracking and their causes in weld zone of 50kg/mm² class high tensile steels, R.T.R.I. (Railway Technical Research Institute) type slit cracking tests were carried out with 46-57kg/mm² high tensile steels and several kinds of electrodes for mild and high tensile steels. Crack appearances, hardness distribution, microstructure and notch profile at root etc. in weld zone were investigated. Diffusible and residual hydrogen content in weld metals was measured. Three types of cracking appeared in the transverse section of weld zone. From experimental results, authors confirmed that considerably intimate relation exists between the types of cracking and the above-mentioned factors.