Substitution of Alloying Elements by Grain Size Control of Alloy Steels

Abstract

Fine-grained steels have many advantages such as are usually obtained through additions of alloying elements; among these are: wider heating ranges and higher grain-coarsening temperatures, relative freedom from low tempe-rature embrittlement, higher toughness at a given strength, less trouble from warping and distortion, greater uniformity in response to heat treatment, and simplification of heat-treating cycles by elimination of treatments such as post-carburizing, refining, etc. It has been brought out in this paper that for many appli-cations grain-refined carbon steels can replace coarse-grained low-alloy steels, excluding, of course, cases where hardenability is critical. The uses of grain-refined steels in automotive applications have been outlined. Grain size control of low-alloy heat-treated steels is part of normal specifications in the U.S.A., but general acceptance of such specifications has been lacking in the U.K. and Europe. In India the U.S.A. grain-size specifi-cation pattern is followed slavishly by some firms, but the other firms follow the U.K. practice. A plea is put forward to rationalize this practice and evolve a uniform attitude to grain size control inthe industry,