Temperature distribution and effect of low-density electric current on B2+O lamellar microstructure of Ti2AlNb alloy sheet during resistance heating

Abstract

The resistance heating method has been one of the prospective techniques for hot processing and welding techniques. The thermal behavior under different densities of electric current and the effect of electric current at temperature of 780 °C using low density of electric current of 6.70 A/mm2 on the B2+O lamellar microstructure were investigated for Ti2AlNb alloy sheet. The stable temperature denoted a balanced state between the Joule heat and the dissipation of heat including heat conduction, convection and radiation while the distribution of temperature was nonuniform. The highest temperatures of electric current heating samples increased as the density of electric current was elevated. In order to understand the specific effect of electric current on B2+O microstructure, heat treatment for microstructural homogeneity was introduced to this study. After that, according to the microstructural observations by common characterization techniques in the resistance-heating sample and the isothermal furnace-heating sample after homogenizing treatment, few significant differences in content and orientation of phases can be directly and explicitly found except the thermal effect from the applied electric current. The results will provide reference to this prospective forming and welding techniques and the application for Ti2AlNb alloys using resistance heating in the near future.