Relation between sensitization and stress corrosion cracking in prior cold-worked SUS 304 steel.

The effect of sensitization on stress corrosion cracking (SCC) of prior cold-worked SUS 304 steel was investigated in boiling 35% MgCl2 solution, and the results were compared with the behavior of intergranular corrosion obtained by Strauss test.The mechanical properties of cold-worked specimens were affected markedly by annealing temperature as compared with annealing time. The cold-worked specimen showed the maximum mechanical strength by annealing at 637K, above which the strength gradually decreased with increasing annealing temperature. The region of sensitization in T-T-S curves shifted to the lower temperature side with increasing prestrain. The susceptibility to intergranular corrosion became maximum at 20% prestrain, but it decreased at 40% prestrain. The susceptibility to SCC of the prestrained specimens increased with increasing annealing temperature and time, and this tendency was consistent with that in the above-mentioned mechanical strength. The susceptibility to intergranular cracking in boiling 35% MgCl2 solution decreased for the specimens treated in the region of sensitization, and this result was not consistent with that of intergranular corrosion behavior in Strauss test solution.