Investigation of mechanical property alterations in DP600 steel under cyclic static strain aging

The aging of commercial DP600 dual-phase steel under different pre-strain levels was conducted up to three times at 140 °C and 190 °C to investigate the effects of cyclic static strain aging (CSSA) on the material's mechanical properties. As the number of CSSA processes increased, the yield stress values exhibited a notable increase compared to those of the raw material. However, the yield strength demonstrated a tendency to decrease when the material was subjected to three cycles of strain aging at 140 °C. The yield stress values of dual-phase steels subjected to strain aging at 190 °C were higher than those of materials aged at 140 °C. As the CSSA temperature increased, the tensile stress values demonstrated a corresponding rise. However, the maximum tensile stress values of dual-phase steel demonstrated a decline with an increase in the number of CSSA repeats. Moreover, a reduction in Brinell hardness values was noted concurrently with an increase in ultimate tensile strength values. However, an inverse relationship was identified between the data points and the yield stress values. It was observed that the continuous yield property of dual-phase steel was lost following two and three CSSA processes at 190 °C.