Means for increasing the toughness and strength of low-carbon steel

Abstract

1. Depending on the service requirements, steel St3 can be used as either a strong material (after quenching with tempering or after microalloying with controlled rolling) or as a ductile material (after thermal cycling). 2. Thermal cycling of low-carbon steel while not increasing its strength, leads to a significant increase in the impact ductility by increasing the work to bring about the nucleation and development of cracks. However, it does not lead to a substantial lowering in the cold brittleness threshold. 3. The formation of a structure consisting of lamina grains of ferrite both free of cementite precipitates and with a dissemination of equally distributed fine cementite particles of spehreical forms will bring about a significant increase in the ductile properties. 4. Thermal cycling is a labor intensive process requiring additional economic cost. Its application is only expedient for cases requiring especially high levels of impact strength.