Damage study of 22Cr2Ni4MoVA steel in artificial crystal growing environment

摘要

Through the chemical analysis, mechanical properties tests, metallographic analysis, fracture and fatigue tests on 22Cr2Ni4MoVA steel cut from deactivated crystal kettle which had been used for 9 years, we obtained a variety of mechanical properties data, and confirmed that the yield strength and ultimate strength of 22Cr2Ni4MoVA steel were basically unchanged in crystal growing environment, but the impact energy, sectional shrinkage and fracture toughness that reflect material toughness were significantly descend, and there existed serious embrittlement and creep deformation. The failure mode of 22Cr2Ni4MoVA steel was brittle fracture under the co-activation of creep fatigue and corrosion. The decline of creep deformation and endurance limit at high temperature played a guiding role; fatigue and corrosion played an initiative attacking role; temper brittleness acted in degenerating, losing immunity and increasing crack sensitivity; while the stress concentration on kettle bottom and alkaline solution with high concentration provided a breeding ground for failure.