THE EFFECT OF STRAIN-AGING ON THE FRACTURE-TOUGHNESS OF SOME STRUCTURAL GRADE STEELS IN THE NIL-DUCTILITY TEMPERATURE-RANGE

The effect of strain-aging on the impact toughness characteristics of Charpy specimens (CVN) and on the quasi-static fracture toughness valu es K-Ic of some structural grade steels, was investigated in the nil-d uctility temperature range. Strain-aging provokes shifts of Charpy cur ves to higher temperatures, but, surprisingly, decreases the nil-ducti lity temperatures with respect to as-received steels. The low temperat ure correlation between K-Ic and the conventional mechanical propertie s confirms that the K-Ic value of as strain-aged steels is higher than that of as-received steels, with similar Charpy impact energy. The sa me probably applies to the stress intensity at crack arrest (K-Ia) as well. Copyright (C) 1996 Canadian Institute of Mining and Metallurgy.