ISSN: 0090-3973
Page Count: 3

A Positron Study of the Quench and Tempering Process in AISI 4340 Steel
Moore, KD
Graduate student and associate professor, Duke University, NC

Jones, PL

Abstract

Dopper broadening measurements of the gamma-ray spectra produced by positron annihilation have been made on an AISI 4340 (Unified Numbering System [UNS] G43400) steel as a function of both isochronal tempering over the temperature range of 150 to 700°C and isothermal tempering at 250°C for times ranging from 1 to 1100 min. Changes in the positron annihilation line shape parameter S are correlated with the corresponding structural transformations that accompany tempering of the as-quenched steel. Of particular significance is the increase in the S parameter in the temper embrittlement regime. This increase in S parameter is postulated to be related to the precipitation of a transition iron carbide that alters the defect structure of the surrounding ferrite phase.

Keywords:
steels, positrons, tempering, positron annihilation, AISI 4340 steel

Paper ID: JTE10782J
DOI: 10.1520/JTE10782J
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