Small but significant dimensional changes resulting from the heat treatment must be considered inevitable. Modelling developments should allow for the numerous contributory factors to be considered in more detail and to be taken into account during processing. At the present time, the main thrust of work for controlling dimensional change must be aimed at improving through processing consistency and making allowances for the changes. Achieving consistency is difficult, even for symmetrical components. With non-symmetric components, the problem becomes even more difficult. With the present day steels, hardenability can be maintained within tight limits and this should provide the optimum control property to ensure the best consistency of transformation temperatures and hence microstructures and distortion.
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