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Title: On the kinetics of transgranular particle embrittlement during simulated carburizing in steel containing grain-refining additions of aluminum and niobium plus aluminum

Here, the kinetics of toughness degradation resulting from transgranular particle embrittlement are evaluated as a function of composition and processing history for simulated carburizing operations in air-melt steel containing grain-refining additions of aluminum and aluminum plus niobium. The kinetics of particle embrittlement are inherently linked to the ripening of AlN precipitates after extended austenitization in steel containing carbon contents representative of both the case and core of a carburized component. Embrittlement in steel containing AlN occurs with an activation energy similar to the value for aluminum diffusion in austenite, although an AlN volume fraction effect on the embrittlement kinetics is manifested as decreases in activation energy with decreases in the [Al]/[N] ratio of steel. In contrast, the presence of niobium substantially retards the kinetics of particle embrittlement in steel containing 120–200 ppm N. Observations of AlN precipitates coated with Nb(C,N) indicate that the decreases in embrittlement kinetics are related to a reduction in the potential for AlN ripening during austenitization.
Authors:
 [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Report Number(s):
LA-UR-17-22819
Journal ID: ISSN 0921-5093; TRN: US1801386
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processing
Additional Journal Information:
Journal Volume: 705; Journal Issue: C; Journal ID: ISSN 0921-5093
Publisher:
Elsevier
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
Universities/Institutions; USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Material Science; case carburizing steel; core microstructure; case microstructure; aluminum nitride; transgranular particle embrittlement; embrittlement kinetics
OSTI Identifier:
1419752