On the Crystallography of Peritectic Austenite and the Role of Primary Ferrite in High Manganese and Aluminum Steels

Abstract

Two high manganese and aluminum steels with duplex mi- crostructures of h-ferrite and austenite, having different weight fractions of primary h-ferrite (0.35 vs. 0.66), were used to study the crystallography of austenite formed during the peritectic reaction. Electron backscattered diffraction (EBSD) was used to characterize the crystallographic growth directions and orientation relationships between the two phases. For a primary h-ferrite weight fraction of 0.66, the peritectic austenite product was seven times more likely to have the Kurdjumov-Sachs (K-S) orientation relationship. In contrast, a lower weight fraction of h-ferrite produced a peritectic reaction where both 8-ferrite and the peritectic austenite product grew with the same <100> or <110> parallel to the heat flux. The K-S orientation was observed for only 5% of the peritectic interfaces. Manganese and aluminum solute profiles across the peritectic interface were used to show that the mechanism of the peritectic reaction remains the same for each alloy. Thermal analysis was used to compare the two alloys at the dendrite coherency point and the alloy with the smaller fraction of primary 5-ferrite had a greater solid fraction (0.4 versus 0.34) at the dendrite coherency point. Copyright © 2012 American Foundry Society.

Department(s)

Materials Science and Engineering

Research Center/Lab(s)

Peaslee Steel Manufacturing Research Center

International Standard Serial Number (ISSN)

1939-5981

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2012 American Foundry Society (AFS), All rights reserved.

Publication Date

01 Jan 2012

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