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Indexed by:期刊论文

Date of Publication:2004-10-01

Journal:Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment

Included Journals:Scopus、EI、PKU、ISTIC

Volume:25

Issue:5

Page Number:1049-1052

ISSN No.:10096264

Key Words:Austenite; Current density; Ion beams; Irradiation; Martensite; Microstructure; Residual stresses; Voltage control; Wear resistance, High speed steel W6Mo5Cr4V2; Intensity pulsed ion beam; Metastable phase; Pulse duration, Steel

Abstract:The structural and phase transformations occurring in the near-surface layers of pre-quenched W6Mo5Cr4V2 high-speed steel (HSS) subjected to intensity pulsed ion beam (IPIB) melting have been investigated. The effect of IPIB irradiation on wear resistance of the HSS has also been studied. The IPIB consists mainly of Cn+(30%) and H+(70%), with a high beam current density of 80 A/cm2, acceleration voltage of 250 kV, pulse duration of 70 ns. Samples were bombarded with 1, 3, 5 pulses respectively. It has been revealed that after IPIB irradiation the initial martensite in the near-surface layer of HSS changed into austenite and produced residual stresses by using electron microscopy and X-ray diffraction. Redistribution and interlace of dislocations in the irradiated samples were generated under the impact of shock wave. With increasing pulse times gradual liquid-phase dissolution of M6C carbide particles occurs in the near-surface layer and produces nanocrystalline MC. This process results in the decrease of martensite crystal (  -phase) and increase of austenite (  -phase) content and the dispersed carbide. Wear resistance of the HSS is improved by a factor of 2, which is explained by the formation of metastable phases, nanocrystal and residual stresses and the redistribution and interlace of dislocations.