Electrolytic Isolation and the X-Ray Study of Micro-constituents in Steels

Abstract

The identification of phases in solid steel specimens is subject to well known limitations. With suitable techniques, however, phases present in exceedingly small amounts can be isolated and identified. The work to be described is represented by three main stages.1.The techniques of isolation. The aim has been simplicity with the maximum efficiency of separation. Simple open and closed type cells are used and a few selected electrolytes for different conditions.2.The second stage is the identification of the separated particles. The X-ray photographs do, however, provide a considerable amount of other data which are often as important as the identity of the constituents. Thus, information can be obtained about the shape and size of particles and lattice spacing changes in solid solution phases. A supplementary determination of the solid solution content of the matrix is often useful.3.The third stage involves the interpretation of the results in relation to the strength and other properties of the steel or alloy. Here such questions arise as the effects of particular carbides or intermetallic phases, solid solution hardening and the times involved in various reactions and their relation to creep, etc.A number of examples are given and some limitations noted.