Study on the morphology and properties of carburized and austempered microstructures in 430 D2 steel

Book · Sun Dec 31 04:00:00 EST 1995

OSTI ID:389742

Xinggui, W; Suidong, Z; Xin, C; Chuenmei, L; Liming, X ^[1]

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1. Univ. of Science and Engineering, Tianjin (China)

By means of carburizing and quenching, a high hard case can be produced in the surface of tool steel, but the brittleness of the case has limited its application in practice. In this paper, structure, composition and properties of the case and core carburized followed by austempering in 430D2 steel was studied. As the result of austempering, the optimum combination of strength and ductility of the carburized case has been achieved. There was no M3C phase in carburized case, indicating that the composition point of the carburized case lies in the M7C3 + Austenite quarter-phase field. In the isothermal period above Ms, lower bainite formed in the core structure, while a needle-like structure without carbides emerged in the outside case after a longer isothermal time. This dark needle-like structure seemed to be the isothermal martensite, which appeared to be dark since it was tempered in the following isothermal process. This tempered isotherm martensite probably improved the toughness and ductility of the carburized case; on the other hand, a large quantity of fine carbide formed in carburizing increased the wear resistance of the die steel and remedied the defect of heterogeneity of carbides in 430 D2 steel.

• OSTI ID: 389742
• Report Number(s): CONF-951222--; ISBN 0-87170-561-3
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AUSTENITE
BAINITE
CARBURIZATION
CHEMICAL COMPOSITION
EXPERIMENTAL DATA
MARTENSITE
MECHANICAL PROPERTIES
MICROSTRUCTURE
MORPHOLOGY
SAMPLE PREPARATION
SCANNING ELECTRON MICROSCOPY
STEELS
TEMPERING
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION