Alloy Partitioning Effect on Strength and Toughness of κ-Carbide Strengthened Steels

Abstract

Alloy partitioning during heat treatment in a lightweight precipitation hardened steel was investigated using transmission electron microscopy and atom probe tomography. The mechanical properties are discussed as a function of the effect of solution treatment temperature and aging time, giving rise to variations in chemical modulation. A wrought lightweight steel alloy with a nominal composition of Fe-30Mn-9Al-1Si-1C-0.5Mo (wt. %) was solution-treated between 1173–1273 K and aged at 773 K. Lower solution treatment temperatures retained a finer grain size and accelerated age hardening response that also produced an improved work hardening behavior with a tensile strength of −1460 MPa at 0.4 true strain. Atom probe tomography indicated these conditions also had reduced modulation in the Si and Al content due to the reduced aging time preventing silicon from diffusing out of the κ-carbide into the austenite. This work provides the framework for heat-treating lightweight, age hardenable steels with high strength and improved energy absorption.

Microstructure evolution and mechanical behavior of Fe–Mn–Al–C low-density steel upon aging

“…Recent studies have focused on the effect of additional alloying elements such as nickel [33][34][35], chromium [36][37][38][39][40], niobium [41], copper [42], sulfur [43], silicon [44], and vanadium [45]. Such elements may change the microstructure constituents and the transformation kinetics [46] and therefore have not been added in the alloy selected in this study.…”

Optimization of Heat Treatment for 38Si7 Spring Steel with Excellent Mechanical Properties and Controlled Decarburization

“…Considerable efforts have gone into developing high-performance spring steel over several decades. Heat treatment processes [ 17 , 18 , 19 , 20 , 21 , 22 ] and microalloying [ 18 , 23 ] are the most effective for intensifying the strength limit. There are, however, only a few systematic studies on the heat treatment of 38Si7 steel with the Φ13 mm specification.…”