An accurate method for determining Young's modulus for ferritic and austenitic steel at high temperatures using acoustic emission tests and inverse solution

Abstract

Young's modulus for ferritic and austenitic steel at high temperatures is typically acquired through acoustic emission tests. In this study, we applied an inverse solution method to consider the effect of a temperature gradient on samples under experimental conditions. Wachman model, Varshni models, and power model were used to describe the influence of temperature on the sound velocity of steel. The constants for these equations were acquired using an optimization scheme that minimized the error between calculated and measured travel times of sound in the samples. Using equations developed for the change in velocity under various temperatures, we calculated Young's modulus at low and high temperatures with acceptable accuracy.This method is non-destructive, and can be applied to measure Young's modulus at different temperatures using a single sample. The acquired Young's modulus values were compared with the results of a modified uniaxial tensile test that accurately measures strain at elevated temperatures. The results showed good agreement between Young's modulus values obtained using the two methods, demonstrating that incorporating the non-linear dependency of the sound velocity on temperature in Young's modulus calculations leads to higher accuracy at low and high temperatures.