石油貯槽の底隅角部の軟鋼隅肉溶接金属部に生じるミクロ割れの再現に関する研究

抄録

Microcracks on the fillet joint between the lowest course shell plate and the annular plate are often detected by M.T. after hydrostatic test. These are delayed crackings due to hydrogen. No one has been studying these cracks in the oil storaged tank. Authors have studied the simulation of these cracks by R.T.T. apparatus and three point bending test. Results are as follows.
1) Microcracks could be simulated by R.T.T. apparatus and three point bending test.
2) Hydrogen distribution in the fillet weld joint is not uniformly. Hydrogen gathers beneath the final pass.
3) Most of microcracks were observed at the regions where hydrogen gathered and hardness increased.
4) Microcrack susceptibility increased by grinder dressing because it makes subsurface area harden.