溶融塩化物腐食中における引張り残留応力をもつSUS304鋼の粒界脆性破壊

抄録

Fracture dynamics of the molten chloride attack of SUS 304 steel with residual tensile stresses was studied using two types of displacement-sensitive heat resistant sensors. AE source simulation of dissipative elastic wave revealed that the Mode-I and -II brittle fractures were associated with the molten chloride attack at 873K. Emission rate of AE signals due to the Mode-I fracture reached the maximum after 15ks exposure and then gradually decreased, while the increase in the AE due to the Mode-II fracture slightly continued until the later period. The fall-off of grains, typical attack morphology by the residual surface tensile stresses, was estimated to be brought by the Mode-I fracture along the grain boundaries perpendicular to the free surface, followed by the mode-II fracture along the boundaries parallel to the surface.