期刊论文详细信息
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING 卷:598
Simultaneous enhancement of strength and ductility in cryogenically treated AISI D2 tool steel
Article
Ghasemi-Nanesa, Hadi1  Jahazi, Mohammad1 
[1] Ecole Technol Super, Dept Mech Engn, Montreal, PQ H3C 1K3, Canada
关键词: Electron microscopy;    Mechanical characterization;    X-ray diffraction;    Steel;    Hardening;    Precipitation;   
DOI  :  10.1016/j.msea.2014.01.065
来源: Elsevier
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【 摘 要 】

In this research, the effect of cryogenic treatment on microstructural evolution and mechanical properties enhancement of AISI D2 tool steel was investigated. Cryogenic treatment down to liquid nitrogen temperature (77 K) was added to the conventional heat treatment between hardening and tempering steps. Electron microscopy investigation showed higher volume fraction of fine carbides with average diameter below 1 mu m indicating effective retardation in carbide coarsening process as a results of cryogenic treatment. A modification in types of carbides was also observed after cryogenic treatment. X-ray diffraction diagrams revealed transformation of retained austenite to martensite at cryogenic temperature. Weakening or removal of carbides peak in the X-ray diagram was considered as evidence of carbides different behavior at cryogenic temperature. Mechanical testing results indicated higher ultimate tensile strength, better ductility, and higher elastic modulus after cryogenic treatment. Analysis of stress-strain diagrams revealed different strain hardening behavior for cryogenically treated alloy when compared to the conventionally heat treated one. Fractography results confirmed strain hardening behavior and showed cleavage fracture for conventionally treated alloy but mixed cleavage-ductile fracture mode for cryogenically treated alloy. The improved mechanical properties after cryogenic treatment are interpreted in terms of the influence of higher volume fraction and uniform distribution of fine carbides in reducing the average active dislocations length and enhancement of the flow stress at any given plastic strain. (C) 2014 Elsevier B.V. All rights reserved.

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