Improvement in Mechanical Properties of Standard 15CDV6 Steel by Increasing Carbon and Chromium Content and Inoculation with Titanium during ESR

Abstract

The AFNOR 15CDV6 steel is high-strength steel with relatively low-level alloy content. In an earlier work, by processing the steel through ESR with inoculation, a marginal increase in strength and further increase in ductility and notch toughness were obtained. But the strength of the steel is inadequate for its use in fabrication of rocket motor casing in the Indian space programme. The present work aimed to increase the strength of the steel by increasing both carbon and chromium content of the AFNOR 15CDV6 steel at the expense of increased ductility and toughness due to processing through ESR. The increase in chromium content is expected to retard the bainite reaction resulting in an increased volume fraction of martensite in the mixed microstructure. Further, addition of chromium also causes secondary hardening during tempering. Another major objective was to study the effect of inoculation during ESR on grain size and mechanical properties. Titanium was used as inoculant in the present work.