Particle deformation and microstructural evolution of high borated stainless steel consolidated by Gleeble-simulated direct powder forging

In the present work, a novel method was first proposed to realise direct powder forging of high borated stainless steel on Gleeble through hot compression tests performed at 1150 degrees C and 0.01-10 s(-1) with strains of 32% and 50%. Particle deformation and microstructural evolution of high borated stainless steel powder during direct forging were investigated. Backscattered electron (BSE) and electron backscatter diffraction (EBSD) were employed for microstructure examination. Microstructure reveals that large deformation zones were easily distinguished by boride and grain features. Enhanced boride coarsening in the contact area of powders was attributed to the combined action of strain, dislocation, stress and temperature rising. Strain rates had no obvious influence on densification but significantly affected the deformation of particles. Furthermore, the mechanism of particle deformation enhanced by a higher strain rate was discussed.