Property Enhancement in Rapidly Quenched Alloy Surfaces
- PDF / 1,381,288 Bytes
- 5 Pages / 417.6 x 639 pts Page_size
- 92 Downloads / 218 Views
ed
1982
by Elsevier
Science
Publishing
RAP-DLY SOLIDIFIED AMORPHOUS AND CRYSTALLINE B.H.
Kear,
B.C.
Giessen,
and M.
Cohen,
Co.,
Inc.
ALLOYS
535
editors
PROPERTY ENHANCEMENT IN RAPIDLY QUENCHED ALLOY SURFACES M. TULI Pilgrim Materials Corporation, 359 Governors Highway, South Windsor, CT 06074 P. R. STRUTT Metallurgy Department, University of Connecticut, Storrs, CT
06268
ABSTRACT Electron beam glazed surfaces on a circular bar are of sufficiently good quality either for direct use or after light mechanical grinding. The technique may be applied for reconstituting plasma deposited layers thereby eliminating porosity and obtaining a highly homogeneous refined microstructure. By this treatment it was found that the microhardness of a plasma deposited layer of chromium carbide in molybdenum binder increased from 525 V.H.N. to 750 V.H.N. INTRODUCTION Hard facing treatments for enhanced wear resistance are currently used in a variety of technological applications. One method for producing such layers is to deposit a carbide particle layer of material on to the surface of an engineering component by plasma spraying. Although recently developed industrial techniques have resulted in plasma deposited layers with reasonably good integrity the residual porosity and imperfect bonding to the substrate markedly limits mechanical performance. The nature of the layer-to-substrate bond is particularly important in such components as a cylindrical shaft or bearing where good resistance to shear at the bond interface is essential. Clearly, therefore, methods need to be developed for significantly improving the deFor these posited layer integrity and the bonding to the substrate material. reasons a study of reprocessing plasma deposited layers by electron beam With this rapid solidification technique a glazing has been undertaken. particularly important effect is the enhancement in hardness and other properties due to ultra microstructural refinement (1-3). In terms of the beneficial effects of laser and electron beam glazing it is pertinent to mention the enhanced wear characteristics of the cemented carbide material Ferro-Tic "SK" following electron beam glazing treatment (4,5). This commercial material consists of 35 volume % distribution of large TiC particles within a tool steel matrix. As a result of combined superheating and liquid turbulence the original carbide particles completely dissolve durin% the gtazingArocess. Upon subsequent solidification at cooling rates of 10 a homogeneous distribution of highly refined TiC carbide dento l10 C.s drites forms. This microstructure produces a significant increase in microhardness and more than a threefold increase in wear life against a conventionally harded M42 tool steel counterface. EXPERIMENTAL TECHNIQUES AND RESULTS Electron-Beam Glazing Techniques. In laser/electron beam glazing a highly focussed beam of radiation impinges upon and moves relative to the surface of a bulk piece of material. As a result a narrow trace of rapidly melted and re-solidified material
Data Loading...
