IMPROVEMENT ON SUSCEPTIBILITY OF ULTAR-HIGH STRENGTH STEEL TO STRESS CORROSION CRACKING BY HIGH TEMPERATURE QUENCHING

The effect of quenching temperature on the stress corrosion cracking of 30Cr3SiNiMoVultra-high strength steel in 3.5% NaCl aqueous solution has been studied.The thresholdK_(ISCC) may continuously increase with the quenching temperature raised from 870 to 1200℃ .All of the fractures are intergranular.The analyses of the segregation along prior austeniticgrain boundaries,grain size and other microstructural factors reveal that the inereaseof K_(ISCC) is mainly due to the coarsening of prior austenitic grains.