Abstract
The effect of position on the face of a steel plate on the quenching process during cooling from a typical austenitisation temperature has been examined. In addition, the effect of plate orientation on the quenching mechanism has been investigated. The most significant effect of these parameters on the quenching process relates to the length of the vapour blanket stage, which is very sensitive to position on the surface of the specimen. This has considerable importance in relation to the production of unhardened regions. A markedly different mechanism of heat transfer during nucleate boiling at different positions on the face did not give rise to corresponding differences in the surface heat transfer coefficients at this stage in the quench. The investigation of heat transfer in the surface of the plate has been supported by still photographs that clearly show the different processes at different positions and orientations of the plate. In particular they show violent disruption of the surrounding quenchant as large packets of vapour are nucleated in quick succession on the underside of a horizontal plate.
MST/3032
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