摘要:

AbstractInvestigations are reported of the response of an alumina fibre–aluminium metal matrix composite system to wear by two-body abrasion. The wear resistance of the composites was found to range from almost two to six times that of the unreinforced matrix alloy. A transition in wear behaviour was found for the various sizes of abrasive particle. With small particles, the wear resistance of the composite increased with increasing fibre volume fraction and the worn surfaces were relatively smooth. With larger particles, the wear resistance decreased with increasing fibre content above a certain level and, on the worn surfaces, fibre fracture and extensive debonding were observed at the fibre/matrix interface. The effect of abrasive particle size on this transition behaviour may be explained by a theoretical analysis of the fracture of a brittle fibre in a ductile matrix under point loading.MST/872

ISSN:0267-0836    

DOI:10.1179/mst.1989.5.1.71

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

AbstractCopper and Cu alloys are considered difficult materials to cut using lasers, because of their high reflectivity and thermal conductivity. This work was performed to examine the potential and limitations of laser cutting these alloys. A series of laser cutting experiments was carried out on Cu, 70–30 brass, and 90–10 Cu–Ni strip using Nd–YAG and CO2lasers of various power capabilities. A higher degree of process efficiency and easier cut initiation were exhibited by Nd-YAG lasers, because of the lower reflectivity of Cu to Nd–YAG laser radiation. It was possible to obtain good quality cuts with the lasers used, although some dross remained beneath the cut, particularly with the higher power laser. The cutting process had no adverse effects on the metallurgy of the strip and no oxidation was observed adjacent to the cut. No dezincification was observed for the brass samples and recrystallisation did not occur in heavily worked materials.MST/892

ISSN:0267-0836    

DOI:10.1179/mst.1989.5.1.77

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

AbstractType 304 stainless steel was welded using argon, nitrogen, and ammonia as shielding gas in gas metal arc welding. Nitrogen diffusion into the base metal was measured using Auger electron spectroscopy, which also permitted the carbides and nitrides formed during the welding and heating processes to be identified. Weldments of higher nitrogen contamination have greater resistance to sensitisation. The best results for arc initiation and stability and for nitrogen diffusion into the base metal were obtained using a shielding gas containing (vol.-%) about 10% nitrogen and 0·5% ammonia.MST/820

ISSN:0267-0836    

DOI:10.1179/mst.1989.5.1.88

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

AbstractThe results of an investigation of the orientation relationships between adjacent plates of acicular ferrite are reported in an attempt to elucidate further the mechanism of acicular ferrite formation. Welds were made using the manual metal arc technique and the as deposited microstructure of the high strength steel weld deposits was examined using crystallography and transmission electron microscopy. It was found that clusters of acicular ferrite form in such a way that adjacent plates tend to have a similar orientation in space; the reasons for this are discussed.MST/903

ISSN:0267-0836    

DOI:10.1179/mst.1989.5.1.93

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

ISSN:0267-0836    

DOI:10.1179/mst.1989.5.1.98

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor