Martensite Volume Fraction Effect on the Dual-Phase SteelWork Hardening Behavior

The present study was aimed to evaluate the dual-phase (DP) steels work hardening behavior in terms of Holloman analysis. Low carbon steel (LCS) was annealed at various temperatures of 780, 800, 820 and 840°C in the Muffle urnace and the effect of the martensite volume fraction (VM) on DP steels work hardening behavior was investigated. The Results revealed that the VM increased from 31% to 66% with increasing annealing temperature from 780 to 840°C. The results of the work hardening mechanism in DP steels showed that with more than 66%VM two stages work hardening occurs and with less than (VM=31, 49 and 55%) one stage took place and the work hardening exponent increased with increasing Vm. Relationship between the VM and carbon content was evaluated by mixture rule and the result indicated that martensite W% decreases from 0.42 to 0.2. with increasing the temperature from 780 to 40°C.Moreover, Elongation and ratio of yield stress to tensile strength decreased with increasing VM.

کلیدواژه ها:

DP steels ، heat treatment ، martensite volume fraction ، Holloman analysis ، mixture rule