摘要:

AbstractDepletion, continuous wear, and over-tempering of high-speed steel cutting tools are discussed, and the differences between these three processes are clarified. All three mechanisms include diffusion, but continuous wear and over-tempering do not yield any concentration gradients in the tool material. Calculations show that depletion of the high-speed steel is not likely to contribute to tool wear. Continuous wear may occur, but could not be detected experimentally. Overtempering does not result in material loss, but makes the tool more prone to wear by other mechanisms, such as superficial plastic deformation and shear fracture. Thus, diffusion does not seem to contribute directly to tool wear.MST/61

ISSN:0267-0836    

DOI:10.1179/mst.1985.1.2.156

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

AbstractThe microstructure and plasticity of a directionally solidified Al-Al6Fe eutectic alloy was investigated using quantitative STEM-EDX microanalysis, in situ tensile testing in STEM/SEM, and light/electron optical studies of microstructure before and following drawing and extrusion to wire. It is found that in spite of the brittle nature of the aligned Al6Fe rods, the alloy as a whole is relatively ductile and can even be drawn or extruded to wire. In the deformed condition the Al6Fe rods are broken up and the fragments distributed uniformly throughout the aluminium matrix. The tensile strength and ductility of these drawn wires are good, 400 MN m−2and 83% area reduction, respectively. Microanalysis studies show that the iron content of the aluminium matrix following solidification is 0·04 at.-%, corresponding to an undercooling of ~3 K below the eutectic temperature. The iron content of the matrix can be reduced further by precipitation treatments.MST/86

ISSN:0267-0836    

DOI:10.1179/mst.1985.1.2.161

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

摘要:

AbstractWork that has helped to improve vacuum induction melting (VIM) procedures for alloy 718 is described. Three aspects of melting in a 5 t industrial VIM furnace are considered: oxygen control by carbon deoxidation; oxygen and sulphur control by alkaline earth and rare earth additions; and the effect of these additions on melt cleanness, with respect to virgin and remelt charge materials. Measurements of total oxygen content and oxygen activity have been carried out on both virgin- and remelt-charged heats. Measured and calculated activity coefficients are compared. In the absence of aluminium, good agreement is found between measured and calculated values. The fact that measured activity coefficients for a complex nickel-based superalloy agree well with predictions based on data for dilute iron alloys could indicate that such data may be useful for predicting oxygen behaviour in a wide range of iron-based and, to some extent, nickel-based alloys. A method for evaluating alkaline earth and rare earth additives in relation to bath sulphur content is given, together with the rate law for the removal of excess residual additives. The effect of these procedures on inclusion density and morphology is discussed.MST/91

ISSN:0267-0836    

DOI:10.1179/mst.1985.1.2.167

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor

ISSN:0267-0836    

DOI:10.1179/mst.1985.1.2.171

出版商:Taylor&Francis    

年代:1985

数据来源: Taylor