Differential resistivity measurement for monitoring annealing

Abstract

An AC differential resistivity technique has been developed to follow the progress of annealing during the heat treatment of cold worked a brass and copper. The method allowed monitoring of all three stages of annealing, i.e., recovery, recrystallization, and grain growth. The decrease in room temperature resistivity due to recrystallization was ∼13 pct and ∼ pct for α brass and copper, respectively. The change in fractional resistivity resulting from primary recrystallization was ∼60 pct for α brass and ∼80 pct for copper; the resistivity method was particularly useful for determining the end point of this stage. Grain growth accounted for a smaller change in fractional resistivity (∼10 pct for α brass and 5 pct for copper); thus, in its present form, the technique is suitable for following only relatively large changes in grain size, of the order of 10 microns.