摘要:

AbstractPreviously drawn copper wires were twisted to large strains (γ≍6) at room temperature under free end conditions. Before testing, individual samples were annealed for 1 h at 150, 200, 250, 300, and 550°C. The specimens heated at 150 and 200°C displayed recovered microstructures, whereas those heated at 250°C and above were recrystallised. During twisting, the recovered samples exhibited shortening behaviour (of up to−4%). In contrast, the recrystallised specimens exhibited lengthening (of up to 3%). Before twisting, the textures were determined by mean of pole figure analysis. Three fibres were identified:〈111〉,〈100〉, and〈112〉–the last appears above the recrystallisation temperature. The changeover in axial behaviour produced by annealing is attributed to the removal of the〈111〉component by recrystallisation. Simulations using the rate sensitive Sachs polycrystal model revealed the roles of the different fibre components. The shortening behaviour is caused by the〈111〉component. The〈100〉fibre together with the random background is responsible for lengthening. The〈112〉component does not affect the axial behaviour significantly.MST/1243

ISSN:0267-0836    

DOI:10.1179/mst.1991.7.5.458

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

Abstractensile, three point bendJc, and Charpy V-notch impact tests were carried out at various loading speeds and temperatures on ferritic, pearlitic–ferritic, and pearlitic spheroidal graphite cast irons. The 0·2% proof stress increased monotonically with decreasing temperature. Similar behaviour was observed for tensile strength, but the temperature range over which it occurred was limited. Both 0·2% proof stress and tensile strength were increased slightly by increasing the crosshead speed. The energy for fracture per unit volume in tensile tests was evaluated as the mean of the tensile strength plus proof stress multiplied by elongation. This energy reveals the ductile–brittle transition behaviour in the same manner asJcvalue or Charpy impact energy. An increase of loading speed shifted the transition curve of the energy for fracture to higher temperature, leaving the upper shelf value unchanged. An increase of pearlite volume fraction in the matrix also shifted the curves to higher temperature, decreased the upper shelf value, and reduced the slope of the transition curve. The transition temperatures of the energy for fractureJcvalue, and Charpy impact energy were found to be linearly related to the logarithm of strain rate.MST/1343

ISSN:0267-0836    

DOI:10.1179/mst.1991.7.5.464

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

AbstractGrain growth is a very commonly observed phenomenon during the elevated temperature deformation of fine grained metals and structural ceramics. It is demonstrated that the occurrence of grain growth can lead to substantial errors in the measurements of the activation energy for plastic deformation. Experimental procedures and analytical techniques are developed to determine the true activation energy for creep and superplasticity by accounting for the occurrence of concurrent grain growth.MST/1263

ISSN:0267-0836    

DOI:10.1179/mst.1991.7.5.469

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

AbstractWC–Co components having one {0001} textured surface have been produced and tested. The textured surface has beenfound to be harder and more resistant to fracture and abrasive wear than standard surfaces. A method is proposed to produce WC–Co components having a bulk {0001} texture.MST/1337

ISSN:0267-0836    

DOI:10.1179/mst.1991.7.5.472

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

ISSN:0267-0836    

DOI:10.1179/mst.1991.7.5.475

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor