Effect of Mn Content on Microstructure and Mechanical Properties of Fe–Mn–Cr–C High‐Manganese Steels Produced Using Laser‐Directed Energy Deposition

Abstract

This study investigates the microstructure and mechanical properties of high–manganese steel (HMnS) fabricated using laser–directed energy deposition (L–DED) with Fe‐Mn‐4Cr‐0.4C alloys with Mn contents of 13, 18.5, and 24 wt%. Additionally, the effect of annealing heat–treatment on the microstructure and mechanical properties of the deposited HMnS is examined. Regardless of the manganese content, the deposited HMnS exhibits a fine microstructure without any defects (cracks or voids) and a strong fibrous texture along the <001>//building direction of the primary austenite phase. In addition, regardless of the manganese content, the grain size increased during annealing heat–treatment, and the hardness decreased as the annealing temperature increased. The strength tended to decrease as the Mn content increased in the as–built state. In addition, regardless of the Mn content, the yield strength and ultimate tensile strength tended to decrease owing to the effect of annealing heat–treatment. Although the maximum elongation of 18.5 and 24Mn did not change significantly upon heat–treatment, the maximum elongation of 13Mn was greatly reduced by annealing. The electron backscatter diffraction analysis in the as–built state indicates that the deformation behavior of HMnS is characterized by transformation–induced plasticity (TRIP) for 13Mn and both TRIP and twinning–induced plasticity for 18.5 and 24Mn.This article is protected by copyright. All rights reserved.