Evidence of Martensitic Transformation in Fe-Mn-Al Steel Similar to Maraging Steel

Gurumayum Robert Kenedy,Yi-Jyun Lin,Wei-Chun Cheng

doi:10.1007/s11661-020-06054-y

Gurumayum Robert Kenedy, Yi-Jyun Lin + Show 1 more

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https://doi.org/10.1007/s11661-020-06054-y

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Abstract

The Fe-Mn-Al steels claim a low density, and some fall into the category of transformation-induced plasticity (TRIP) steel. In Fe-Mn-Al TRIP steel development, phase transformations play an important role. Herein, the martensitic transformation of an Fe-16.7 Mn-3.4 Al ternary alloy (wt pct) was experimentally discovered, whose equilibrium phases are a single phase of austenite at 1373 K and dual phases of ferrite and austenite at low temperature. Ferritic lath martensite forms in the prior austenite grains after cooling from 1373 K under various cooling rates via quenching, air cooling, and furnace cooling. The formation mechanism of the ferritic lath martensite is different from that of traditional ferritic lath martensite in steel and quite similar to that in maraging steel. A slight strain energy coupled with a small temperature gradient can lead to the formation of ferritic lath martensite in the Fe-Mn-Al alloy after cooling from high temperature. It is also found that micro-twins exist in the ferritic lath martensite.

Highlights

FE-MN-AL alloys exhibit a low density and some fall into the category of transformation-induced plasticity (TRIP) steels, while Fe-Mn-Al alloys that contain high concentrations of aluminum and manganese have the superior properties of low cost and low density
The crystal structures of the alloy were examined by XRD in Figure 1(c), which shows that the as-quenched Fe-Mn-Al alloy is composed primarily of body-centered cubic (BCC) ferrite and a minor amount of face-centered cubic (FCC) austenite
The austenite–ferrite martensitic transformation appears in the Fe-16.7 Mn-3.4 Al alloy when cooled from high temperature

Summary

Introduction

FE-MN-AL alloys exhibit a low density and some fall into the category of transformation-induced plasticity (TRIP) steels, while Fe-Mn-Al alloys that contain high concentrations of aluminum and manganese have the superior properties of low cost and low density. A higher manganese content in the alloy produces a higher proportion of austenite, unlike the Fe alloys at low temperature that are primarily ferrite.[1,2,3,4] in Fe-Mn-Al alloys possessing a low concentration of aluminum and a high concentration of manganese, a fully austenitic microstructure can be preserved even at low temperature.

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