High-strain rate and low-temperature superplasticity of Fe-Mn-Si-Ni steel

Superplastic steels with high elongation above 300% are expected to be used to manufacture complexshaped mechanical parts without joining. However, their practical application is difficult due to high energy consumption and low productivity caused by high deformation temperature and low strain rate. In the present study, we newly developed an Fe-Mn-Si-Ni steel, which exhibited superplasticity at a low temperature of 1023 K and a high strain rate of 1 x 10-1 s-1. This steel also had remarkable room-temperature tensile strength (-1.3 GPa) and total elongation (38%) after a simulation of superplastic forming. The mechanism of excellent superplasticity is grain boundary sliding occurring at the boundaries of fine gamma grains, whose coarsening was suppressed by both Fe5(Mn,Ni)3Si2 and (Fe,Mn,Ni)3Si precipitates.(c) 2023 Elsevier B.V. All rights reserved.

Automated summary

In this study, a Fe-Mn-Si-Ni steel was developed to exhibit superplasticity at a low temperature and a high strain rate, while maintaining remarkable room-temperature tensile strength and total elongation. The excellent superplasticity was achieved by grain boundary sliding at the boundaries of fine gamma grains, which were prevented from coarsening by Fe5(Mn,Ni)3Si2 and (Fe,Mn,Ni)3Si precipitates.