Phase and Structural Transformations in the Fe-Based Alloys under the Combined High-Energy Treatment

Abstract

Applying the x-ray, metallographic, and microdurometric methods, the phase composition and structural–stress state of the Fe-based alloys under the impact of electrospark treatment in combination with laser processing are studied and analysed. As shown, the structural–phase state of electrospark coating on the steel substrate is determined by several factors. They are the dissociation of WC carbide on the surface of alloying electrode on the W2C and W components followed by their erosion, an interaction of erosion products with elements of the interelectrode medium (C, N, O), an interdiffusion of the coating elements and a steel substrate, and the ascending diffusion of C from the substrate near-surface layers. As revealed, the heterophase coating and near-surface layers of substrate possess a complex structural–stress state. As shown, the residual stresses in different phase components have been formed through different regularities: the tensile stresses in the TiC-based compound, while the compressed stresses in the W2C, W, and Feα. The selective effect of laser heating of the coating on the stresses of different signs is revealed.

Keywords

• electrospark treatment
• laser treatment
• residual stress
• martensitic transformation
• erosion
• diffusion
• mass transfer
• carbide
• nitride.