Effect of Multistage Heat Treatment on Microstructure and Mechanical Properties of High-Strength Low-Alloy Steel

Abstract

The influence of Cu-rich precipitates (CRPs) and reverted austenite (RA) on the strength and impact toughness of a Cu-containing 3.5 wt pct Ni high-strength low-alloy (HSLA) steel after various heat treatments involving quenching (Q), lamellarization (L), and tempering (T) is studied using electron back-scatter diffraction, transmission electron microscopy, and atom probe tomography. The QT sample exhibits high strength but low impact toughness, whereas the QL samples mostly possess improved impact toughness but moderate strength, but the QLT samples again have degraded impact toughness due to additional tempering. The dispersion of nanoscale CRPs, which are formed during tempering, is responsible for the enhanced strength but simultaneously leads to the degraded impact toughness. The RA formed during lamellarization contributes to the improved impact toughness. Based on the present study, new heat treatment schedules are proposed to balance strength and impact toughness by optimizing the precipitation of CRPs and RA.

Department(s)

Materials Science and Engineering

International Standard Serial Number (ISSN)

1073-5623

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2016 Springer Boston, All rights reserved.

Publication Date

01 May 2016

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