Effects of Phosphorus on Microstructure and Mechanical Properties in NiCr Alloys

Abstract

Microstructure and mechanical properties of Ni-Cr alloys with various contents of Phosphorus (P) have been investigated. It is found that the increase of phosphorus refined dendritic structures in as-cast alloys and decreased micro-segregation of Chromium (Cr) element. α-Cr which precipitated during hot-rolling process was obviously inhibited by phosphorus because of its prior occupancy on grain boundaries and decreasing precipitation driving force of α-Cr. Tensile and impact properties were examined on samples under different heat treatments. Though the yield strength of as-rolled alloys was increased by precipitation of α-Cr, the elongation and impact energies were reduced. It is worthy to note that impact energies of samples solutioned at 950°C increased with the increasing phosphorus. The results indicated that dislocations are markedly effected by phosphorus which is probably the reason for improving impact energies.