EFFECTS OF MICROSTRUCTURES ON THE MECHANICAL PROPERTIES OF MULTI-PHASE SHEET STEELS.

Abstract

Several microalloyed steels were intercritically annealed and air-cooled to room temperature or water quenched to obtain different microstructures. The effect of the amount and nature of low temperature transformation products on deformation behavior, stretch-flangeability and fracture toughness after cup deep-drawing were examined. Bainite has a slight deleterious effect on strength but has a favorable effect on stretch-flangeability and fracture toughness compared with martensite. Ferritic-bainitic ( minus martensitic) steel may be preferred to dual phase steel in some complex pressings. 17 refs.