THE OBSERVATION OF THE MARTENSITE-LIKE SHEAR DIFFUSIONLESS ALPHA-]GAMMA TRANSFORMATION IN CARBON-STEELS WITH PEARLITIC STRUCTURE

The structure of eutectoid carbon steel with the initially pearlitic s tructure was studied by transmission electron microscopy and electron diffraction after laser heating. It is shown that, under ultrarapid la ser heating, the alpha-gamma phase transformation can proceed by a she ar-type diffusionless mechanism that results in the deformation of cem entite platelets. The crystallographic characteristics of shear planes involved in the alpha-gamma transformation are determined. Austenite formation was found to occur through the diffusionless shear mechanism , with orientation relationships close to those of Kurdjumov-Sachs.