The dual effects of phosphorus on the hot deformation behavior in an as-cast Ni-Fe-Cr based alloy

Abstract

The effect of phosphorus on dynamic recrystallization (DRX) and hot deformation behavior of an as-cast Ni-Fe-Cr based was investigated by performing hot compression deformation. The results indicate that phosphorus can play dual roles during hot deformation. The phosphorus dissolving in matrix and segregating to the dislocation can hinder the dislocation motion and DRX nucleation, which acts as the solute drag effect. And phosphorus-addition can increase the size and number of MC carbides. MC carbides increase the local dislocation density around them and promote the DRX nucleation and exhibit the particle stimulated nucleation effect. Influenced by the dual effects of phosphorus, the DRX fraction and grain size decrease first and then increase with the increase of phosphorus content. The solute drag effect of the substitutional phosphorus atoms on dislocation motion decreases the DRX nucleation rate and increase the possibility of instability at low deformation temperature in phosphorus-addition alloys. In the early stage of deformation, more MC carbides in the high-phosphorus alloy hinder the motion of dislocation and result in the stress concentration, which leads to the intergranular cracks at high temperature and high strain rate.