Effects of Deformation Strains and Annealing Temperatures on Mechanical Properties of Martensitic Steels

Abstract

The effects of deformation strains and annealing temperatures on microstructures and mechanical properties of martensitic steels were examined. The amount of cold deformation was changed as 30%, 50% and 60%, and annealing temperatures varied from 500°C to 600°C. In samples cold rolled 30%, the dominant microstructure for an annealing at 500°C was dislocation substructures with uniformly distributed rod-shaped carbide particles. For an annealing at 600°C, the microstructure consisted of equiaxed ultrafine grains, spherical carbide particles and elongated dislocation substructures. A proper annealing temperature for martensitic steels received 30% reduction, showing a good combination of a high strength, 1230MPa, and an adequate total elongation. 9.4%, was found as 500°C.

An Original Way for Producing a 2.4 GPa Strength Ductile Steel by Rolling of Martensite

“…In order to compare the present results with the previous works [6,7] on cold-rolled martensite, the maximum strength versus equivalent Von Mises strain produced by coldrolling are reported in Fig. 4.…”

“…Unfortunately this technique is limited by the ability to cold roll martensite to high levels of deformation. In previous studies 6,7) the carbon content of the martensite is not higher than 0.25%C and the maximum equivalent strain is not more than 1. This is once again due to the fact that for higher carbon content martensite is brittle.…”

“…The level of strength of this material is high (up to 2.5 GPa) but the ductility in tension and the work hardening are limited. 1) Recently different studies [2][3][4][5][6][7] showed the possibility to obtain UFG by cold rolling martensite and/or annealing at warm temperature. For this material it is possible to obtain high ductility (13.2% elongation) with relative high strength (1 300 MPa) but the work hardening is very low.…”