摘要:

AbstractSeveral Fe–Al and Fe–Al–Zn alloys were vacuum melted, annealed at 450°C under atmospheric pressure, and then quenched in iced water. The structure and composition of phases were determined using microstructural, X-ray diffraction, and X-ray energy dispersive analyses. The maximum solubility of zinc was found to be 5·3 wt-% in FeAl3, 20·9 wt-% in Fe2Al5, and 2·0 wt-% in FeAl at 450°C. Based on these results, an isothermal section for the aluminium rich corner of the Fe–Al–Zn ternary phase diagram is proposed.MST/1196

ISSN:0267-0836    

DOI:10.1179/mst.1990.6.12.1173

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractInterdiffusion measurements of Nb and Ta in Fe base alloys have been made. Dilute alloys containing up to 0·6 wt-%Nb or 0·56 wt-% Ta were prepared. Diffusion couples of these alloys against pure Fe were made by spot welding. After vacuum annealing, diffusion profiles were obtained using electron probe microanalysis. The diffusion parameters were determined at one standard deviation using the Grube method. In austenite, interdiffusion of Nb is in good agreement with previous tracer diffusion data. The diffusion rate of Ta in austenite is approximately six times that for self-diffusion of Fe. Inferrite, diffusion of Ta produces a higher value of activation energy than other transition metals. Attempts to measure the diffusivity of Nb inferrite failed owing to the different levels of concentration and the presence of an intermetallic phase. However, a solubility of Nb inferrite of less than 0·24 wt-% is reported.MST/1162

ISSN:0267-0836    

DOI:10.1179/mst.1990.6.12.1177

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractThe influence of the parameters of an additional tempering at 600°C on temper embrittlement in quenched and previously double tempered 5 wt-%Cr tool steel having a post-martensitic microstructure was investigated. A detailed examination of associated changes of fracture mechanism, microstructure, and precipitate was carried out. The dominant factor controlling the evolution of brittleness was the segregation of phosphorus to prior grain and lath boundaries as well as to martensite lath/carbide interfaces. The segregation effect of phosphorus at these interfaces was accompanied by cosegregation of sulphur and silicon together with simultaneous carbide precipitation.MST/1132

ISSN:0267-0836    

DOI:10.1179/mst.1990.6.12.1181

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractLow cycle fatigue properties of austenitic steels and aluminium alloys are discussed. Curves of stress S–number of cycles to failure N for three alloys are presented. The form of the S–N curve is described and the various equations used by designers to represent the curve are discussed. It is suggested that microstructurally related parameters could be inserted in these parametric design equations. Attempts at achieving this objective using a disclocation stress and a fracture toughness related model are described. It is shown that reasonable fits between predicted and experimental S–N curves result from the application of the dislocation stress model, whereas the fracture toughness approach seems less successful.MST/1163

ISSN:0267-0836    

DOI:10.1179/mst.1990.6.12.1187

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractAn investigation of the effect of Nb on creep properties and creep crack growth rate in a 25Cr–35Ni–0·4C (wt-%) cast steel at 871 and 950°C was carried out. Tensile tests were also carried out at room temperature, 871, and 950°C. The tensile strength and elongation increased with an increase in Nb content at high temperatures. There existed an optimum Nb content for the creep properties and creep crack growth rate. Creep crack growth is controlled by creep deformation.MST/1222

ISSN:0267-0836    

DOI:10.1179/mst.1990.6.12.1193

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractProcedures for plane strain fracture toughness tests on a number of particulate reinforced aluminium alloy metal matrix composites (MMCs) have been examined. Measurements of toughness are reported on a range of particulate aluminium alloy MMCs and the results are compared with validity criteria in standards for metallic materials. In particular, the effect of testpiece thickness was studied in a 6000 and a 2000 series aluminium alloy containing, respectively, 25 and 30% silicon carbide. The results are compared with other published work on the toughness of particulate reinforced MMCs.MST/1225

ISSN:0267-0836    

DOI:10.1179/mst.1990.6.12.1199

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractIn steel frame construction of multistorey buildings, the structural steel members are coated with an insulating material to give them protection in the event of afire. This requirement can double the cost per ton of steel used. The 0·2% proof stress of the standard 250 and 350 grades of steel used commonly in such buildings is reduced to half its room temperature value at about 570°C. Newly developed microalloyed high strength low alloy steels with an acicular ferrite/bainite microstructure are shown to retain half of their room temperature proof stress at about 670°C, thus reducing the insulating requirements.MST/1207

ISSN:0267-0836    

DOI:10.1179/mst.1990.6.12.1210

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractThe effect of various post-weld heat treatment (PWHT) cycles on the as welded heat affected zone (HAZ) microstructures of C–Mn steels microalloyed with niobium, or niobium plus vanadium, has been studied. Single pass welds were produced at an arc energy of 3·5 kJ mm−1; examination was carried out using optical and electron microscopy, along with hardness and crack tip opening displacement testing. As welded, the C–Mn–Nb HAZ contained a significant proportion of auto tempered martensite. After PWHT at 550°C, isolated hard regions remained, but at 600°C all hard regions had been removed, with a concomitant increase in cleavage resistance. In contrast, ferrite with aligned second phase with lower hardness was found mainly in the as welded HAZ of the C–Mn–Nb–V steel. When the PWHT temperature was raised, HAZ hardness increased to a maximum at 600°C; overaging would be required to obtain improved toughness, although this would soften the parent plate. The results indicate that the current practice of specifying a common heat treatment procedure for steels to a given specification is not satisfactory; allowance should be made for the particular composition and as welded HAZ microstructure.MST/1190

ISSN:0267-0836    

DOI:10.1179/mst.1990.6.12.1215

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractThe effect of 0·2%Be on the aging behaviour and microstructure of Al–0·2% Ti alloy is investigated. It is shown that the addition of Be induces some age hardening in non age hardenable AI–0·2Ti alloy and significantly increases the precipitate density, indicating a Be enhanced nucleation for the precipitate phase.MST/1250

ISSN:0267-0836    

DOI:10.1179/mst.1990.6.12.1227

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

AbstractComputer simulated orientations of individual grains in an austenitic steel having a {011}〈211〉rolling texture and a {311}〈112〉recrystallisation texture have been generated. These data were used as input to calculate the distribution of misorientations–the‘meso texture’–that evolves. First and second order twinning in the recrystallised grains were incorporated into the model. The results showed that the preferred misorientations were those coincident site lattices (CSLs) whose rotation axis was 210 or 331. The possibilities for CSL generation at impinging recrystallised grains was also explored, and it was found that the same family of CSLs could regenerate. The simulated data were in excellent agreement with experimental mesotexture data from partially recrystallised specimens of austenitic steel.MST/1269

ISSN:0267-0836    

DOI:10.1179/mst.1990.6.12.1231

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor