Electrical Resistivity and Phase Transformation in Steels

Abstract

Abstract Changes in electrical resistance accompanying transformations in steels with magnetic change (e.g. γ → martensite/bainite) and without magnetic change (e.g. γ → α, above Curie temperature) have been examined; the former class affects the resistivity the latter does not. Next, while the efficacy of electrical resistivity measurement in capturing the well‐known features of austenite stabilization (e.g. over – ageing, reversibility, and influence of prior martensite amount and so on) in high carbon steels has been reported in an earlier publication, new features (e.g. increase in resistance ‐increase at very low temperatures, change in temperature co‐efficient of resistivity in the stabilized material etc.) are highlighted here. Finally, the work shows that a quantitative estimate of precipitation in the copper bearing, age‐hardenable HSLA‐100 steel during tempering can be done by continuous electrical resistivity measurement. These data also allow an in‐depth kinetic analysis using the Johnson‐Mehl‐Avrami equation.