Metals technology 

About: Metals technology is an academic journal. The journal publishes majorly in the area(s): Ultimate tensile strength & Austenite. It has an ISSN identifier of 0307-1693. Over the lifetime, 707 publications have been published receiving 8995 citations.

Determination of flow stress: Part 1 constitutive equation for aluminium alloys at elevated temperatures

Abstract: An alternative form of the hyperbolic sine relationship is developed for use as a constitutive equation at elevated temperatures. It is shown how an optimization technique may be applied to results from torsion tests to determine the constants in this equation and that this method must be more accurate than those presented previously. Experimental results for two aluminium alloys indicate that the activation energy during hot torsion testing is the same as the activation energy for bulk self-diffusion. It is shown that thermal changes occurring during testing affect results significantly.

Hot-ductility behaviour of C–Mn–Nb–Al steels and its relationship to crack propagation during the straightening of continuously cast strand

Abstract: The influence of composition on the tendency for surface-crack propagation to occur on straightening of continuously cast strand of a commercial C–Mn–Nb–Al grade of steel has been examined and compared with the hot-ductility behaviour obtained from Gleeble tensile tests, using reduction of area as the measure for hot ductility. The tendency for surface-crack propagation was found to increase with Nb and soluble Al addition and to decrease with a rise in the P level. Hot ductility was also found to be affected in a similar manner by these elements. The results have been interpreted in terms of differences in the effectiveness of the NbCN precipitation in pinning the γ grain boundaries during deformation. From the close agreement between the hot-ductility behaviour as given by the Gleeble tests and the tendency for surface cracks to propagate during straightening of these steels at the exit from the continuous-casting machine, it has been concluded that the Gleeble test can be used with a fair degre...

Influences of superheat and grain structure on hot-tearing susceptibilities of AI-Cu alloy castings

Abstract: An investigation has been carried out under controlled solidification conditions, regarding the manner in which composition, melt superheat and grain structure interact to determine the hot-tearing susceptibilities of Al- Cu alloys in the range 0·15 wt-% Cu The results demonstrate that the influence of both superheat and grain structure relates to the way in which these variables affect the number of potential sites of crack origin This number then has to he considered in conjunction with the mechanisms that can operate to withstand hot tearing which are themselves dependent on metal composition Under the experimental conditions employed, cracking, as detected by measurement of electrical resistance only ever occurred in alloys containing less than 7 wt-% Cu The actual composition range within which cracking was observed was dependent on grain structure and superheat Increasing superheat increased the susceptibility to tearing of an alloy of fixed composition and hence the composition range

Gradual changes in residual stress and microstructure during contact fatigue in ball bearings

Abstract: Deep-groove ball bearings have been endurance tested at high stress levels. The purpose of the work was to study the simultaneous generation of residual stresses and occurrence of structural changes owing to cyclic rolling contact fatigue. During the investigation the decomposition of both retained austenite and parent martensite were followed. The residual stresses and the austenite decomposition were measured by an X-ray diffraction technique, using signal averaging. Optical and transmission electron microscopy were used to observe the transformed regions resulting from the martensite decay. Depth profiles of residual stress and of successive structural changes were constructed. The observations are discussed in terms of a qualitative model for residual-stress generation under cyclic rolling contact.