Detailed studies are conducted on the microstructural evolution and mechanical behavior of a high strength low alloy (HSLA) steel processed by warm multiaxial forging (MAF). After nine MAF strain steps, the initial ferrite grains of average 13-lm size reduced to submicron-sized grains with over 0.7 fraction of high angle grain boundaries. Pearlitic cementite is fragmented and refined to about 50-100 nm size particles. The microstructure evolution with respect to fraction of HAGB with increase in number of strain steps is more sluggish in HSLA steel as compared to plain carbon steel of comparable carbon content. This is ascribed to the Zener pinning effect of (Ti, Nb) carbide particles. Tensile strength and hardness values of MAFed steel increased by more than 45 and 58 %, respectively, after nine warm MAF strain steps, whereas the fracture strain was reduced from 21 to 12 %.
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