New insights into the properties of high-manganese steel

Wolfgang Bleck

doi:10.1007/s12613-020-2166-1

Abstract

In the Collaborative Research Centre 761’s “Steel ab initio - quantum mechanics guided design of new Fe based materials,” scientists and engineers from RWTH Aachen University and the Max Planck Institute for Iron Research conducted research on mechanism-controlled material development with a particular focus on high-manganese alloyed steels. From 2007 to 2019, a total of 55 partial projects and four transfer projects with industrial participation (some running until 2021) have studied material and process design as well as material characterization. The basic idea of the Collaborative Research Centre was to develop a new methodological approach to the design of structural materials. This paper focuses on selected results with respect to the mechanical properties of high-manganese steels, their underlying physical phenomena, and the specific characterization and modeling tools used for this new class of materials. These steels have microstructures that require characterization by the use of modern methods at the nm-scale. Along the process routes, the generation of segregations must be taken into account. Finally, the mechanical properties show a characteristic temperature dependence and peculiarities in their fracture behavior. The mechanical properties and especially bake hardening are affected by short-range ordering phenomena. The strain hardening can be adjusted in a never-before-possible range, which makes these steels attractive for demanding sheet-steel applications.

Highlights

Since the mid-1990s, considerable progress had been achieved in modeling and measurement technologies, which has enabled the systematic knowledge-based development of the demanding new material group of high-manganese alloyed steels
As a central scientific working hypothesis of the Collaborative Research Centre 761 (CRC), which was established by Deutsche Forschungsgemeinschaft DFG in 2007, it was assumed that the stacking fault energy (SFE), in particular, controls the deformation mechanisms
Small grain sizes and homogenous grain-size distributions are of primary interest

Summary

Introduction

Since the mid-1990s, considerable progress had been achieved in modeling and measurement technologies, which has enabled the systematic knowledge-based development of the demanding new material group of high-manganese alloyed steels. With these high-manganese steels (HMnS; up to 30wt% Mn), extraordinary phenomena in plastic deformation are observed and, on this basis, exceptional property combinations can be realized. As a central scientific working hypothesis of the Collaborative Research Centre 761 (CRC), which was established by Deutsche Forschungsgemeinschaft DFG in 2007, it was assumed that the stacking fault energy (SFE), in particular, controls the deformation mechanisms. The investigations range from fundamental questions about the deformation mechanisms to questions of manufacturability, to technological investigations into the application potential with a

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Conclusion