Study of a nearly Ni-free V-containing lean duplex stainless steel and the deformation mechanism

Abstract

A novel nearly Ni-free V-containing lean duplex stainless steel with the composition of Fe-0.1C-20Cr-5Mn-0.2Ni-0.2N-0.18V (V-LDSS) was developed, with a low content of the precious element Ni and good mechanical properties. In the present study, the microstructures, mechanical properties, precipitate behaviors, and the evolution of the microstructural features under different logarithmic strains of the V-LDSS at different annealing temperatures were investigated. The results indicated that the annealing temperature had significant influences on the precipitation behavior, the volume fraction of the austenite phase, and the grain size of the V-LDSS. The tensile curves changed from discontinuous yielding to continuous yielding, under the control of the precipitate behavior and the phase content of ferrite. The deformation mechanism revealed the synergistic deformation behavior of the transformation-induced plasticity (TRIP) effect in the austenite and the rapid growth of dislocations in the coarse ferrite, resulting in excellent plasticity of the current V-LDSS. After annealing at 1125 °C for 5 min, the annealed samples showed a good combination of the ultimate strength and elongation.