Boronising Behaviour of Ni–Si–Cr Steel

Abstract

I sothermal and isochronal boronising experiments were carried out using a mixture consisting of 92%SiC, 5%B₄C, and 3%KBF₄ on Ni–Si–Cr steel. The boride surface, the interface, and the matrix were characterised by electron probe microanalysis, microstructural examination, X-ray diffraction, and microhardness measurements. In contrast to the reported literature, it was shown that the boronising behaviour of the Ni-Si-Cr steel was similar to that of many low alloy steels. It was further established that the interface layer was not ferrite, as reported for silicon rich steels, but was a borzde of the type Fe₃(SiB).