Effect of Intercritical Heat Treatment on Mechanical Properties of Plain Carbon Dual Phase Steel

Mechanical properties of DP (Dual Phase) steels are greatly influenced by the microstructural features such as grain size, morphology and martensite volume fraction (Vm%). These microstructural features can be altered by changing the soaking time and temperature within intercritical zone. Present study aims to study the effect of intercritical annealing temperature and soaking time on Vm% and its effects on mechanical properties of plain low carbon steel grade (AISI 1020) steel having ferritemartensitemicrostructure. Nine DP steel specimens with various amount of martensite were produced via intercritical heat treatment. Mechanical properties including TS (Tensile Strength), hardness and toughness were characterized and co-related with martensite volume fraction. It was found that increasing the intercritical annealing temperature and soaking time increases the Vm%. The optimum TS and hardness were found at 64Vm% and then decrease with further increase in Vm%. The toughness was found to have linear relationship with Vm%.