Linear heat source surface melting studies have been carried out using a 1 to 15 kH oscillating beam incident on a steel substrate to produce a 3 to 35mm wide rapidly solidified strip of material at rates ranging from 1 to 100 cm.s−1. A simple relationship betweenmelt depth, power, and substrate velocity (V) has been determined at low values of V; limited results at higher velocities appear to follow the same relationship. A serendipitous discovery was the effect of prior surface homogenization treatment on the geometrical and microstructural uniformity of the subsequently formed rapidly solidified layers. This pre-treatment resulted in the formation of thin layers of uniform thickness under the most rapid processing condition (V = 100 cm.s−l). Omission of pre-treatnent resulted in irregular and sometimes discontinuous surface layers. In the case of a high speed steel of near peritectic composition (M2)pre-treatment resulted in the almost complete elimination of massive austenitic region within the dominant ferrite phase.
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