The stress corrosion cracking of sensitized Inconel 600 was studied in sodium tetrathionate solution. The constant strain test of C-ring showed that the cracks were intergranular and occurred under heat treatment conditions of 600℃ for 10, 24hr and 650℃ for l, 10hr after solution annealing at 1100℃ for 30min. Degree of sensitization was estimated using Double Loop EPR test, then Ir to Ia ratio increased with increasing heat treatment temperature and time. At 650℃ and 700℃, the ratio was maximum at 0.6. The ratio of 0.5 corresponded to crack initiation conditions in constant strain test with an exception of 650℃/10hr. When semi-continuous carbide precipitated dominantly along grain boundaries, stress corrosion cracking resistance was improved.
