Revealing working hardening behavior and substructure evolutions of ultrahigh strength and enhanced wear resistance Fe–25Mn–7Al–1C steel treated by explosion processing

The substructural evolution and working hardening behavior of Fe–25Mn–7Al–1C steel after explosion processing were investigated in the present study. After solution treatment at 1100 °C for 2 h and aging treatment at 550 °C for 2 h, the wear surface of the steel was treated by explosion processing. The results showed that the hardening surface exhibited an excellent combination of mechanical properties including ultimate tensile strength of 999.1 ± 9.3 MPa, yield strength of 900.5 ± 7.9 MPa, total elongation of 13.8 ± 0.4% and hardness of 400 HB. Under the impact energy of 1 J, 2 J and 4 J, the morphologies of worn surface consisted of the furrow, delaminated crater and press-in abrasive. The hardness, strength and decreased gradually with the increase in hardening depth. The deformation characteristic was the typical planar glide due to glide plane softening. In the process of hardening, microband, Taylor lattice and a large number of slip bands were orderly formed. These dislocation substructures interacted with dislocations and hindered dislocation motion, leading to the surface hardening and the improvement of hardness, strength and wear resistance. It is worth noting that microband increased the work hardening rate, but the width and density of it played a small role in improving the strain hardening capacity. In addition, with the strain increasing, microband had different effects on strain hardening rate of the steels with different initial dislocation densities.