Insights into the dynamic impact behavior of intercritically annealed automotive-grade Fe-7Mn-4Al-0.18C steel

被引：16

作者：

Mohapatra, Sudipta ^{[1
]}

Poojari, Govardhana ^{[1
]}

Das, Siddhartha ^{[1
]}

Das, Karabi ^{[1
]}

机构：

[1] Indian Inst Technol, Dept Met & Mat Engn, Kharagpur 721302, India

来源：

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING | 2023年 / 887卷

关键词：

Medium manganese steel; Annealing time; Impact behavior; HAGB; TRIP effect; Texture; MEDIUM-MN STEEL; MEDIUM-MANGANESE STEEL; MECHANICAL-PROPERTIES; TENSILE PROPERTIES; AUSTENITE REVERSION; RETAINED AUSTENITE; ULTRAHIGH STRENGTH; GRAIN-BOUNDARIES; TOUGHNESS; MICROSTRUCTURE;

D O I：

10.1016/j.msea.2023.145769

中图分类号：

TB3 [工程材料学];

学科分类号：

0805 ; 080502 ;

摘要：

Recently, medium manganese steels (MMnS) have been developed due to their excellent strength and improved ductility to meet automotive manufacturer demands. However, research on the impact toughness of automobile parts developed from these steels needs considerable attention to meet safety standards. Therefore, the present investigation focuses on the effect of annealing time (30, 60 and 180 min) on the impact behavior of intercritically annealed (750 degree celsius) Fe-7Mn-4Al-0.18C (wt. %) steel. The microstructure of intercritically annealed steel, as revealed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), consists of blocky and lath-type reverted austenite (RA), fine intercritical ferrite (IF), lath-type martensite (M) and coarse elongated ferrite (EF). The impact toughness of the samples is evaluated at room temperature using a Zwick/ Roell HIT450P Charpy impact machine. The sample annealed for 60 min absorbs the highest amount of impact energy among the three annealed samples. This is due to an increased volume fraction of RA, the transformation-induced plasticity (TRIP) effect, and an increase in the fraction of high angle grain boundaries (HAGBs). The microtexture analysis reveals that the presence of gamma-fiber {111}//ND texture in ferrite and Rotated Goss texture {011} <011> in austenite contributes to the improved impact toughness in the specimen annealed for 60 min. The SEM fractographs of the sample annealed for 60 min exhibit crack branching and larger dimple size with inhomogeneous dimple distribution indicating higher energy absorption during crack initiation. Martensitic transformation nucleation sites are activated by a high volume fraction of RA in the sample annealed for 60 min, leading to increased impact toughness and the development of secondary cracks. In addition, the impact energy decreases when the sample annealed for 60 min is subjected to an impact test at temperatures lower than room temperature.

引用

页数：13