Influence of thermocouple welding on the Gleeble temperature measurement error and a scheme for its correction

Abstract

<p indent="0mm">Finite element analysis was performed to model the process of thermal compression of titanium alloy rods on Gleeble 3800, concentrating on the effect of thermocouple welding on the accuracy of temperature measurement during the Gleeble test. The study shows that the thermocouple application distorts the local temperature distribution around the welding area, and cause errors in temperature measurement. Analysis of the influence of different factors shows that the change in the thermal conductivity of the thermocouple materials, the separation of the thermocouple wires, the change in the contact area of the thermocouple wires with the sample, the deviation of the welding points from the mid-point of the samples, and even the twining of the thermocouple wires will lead to the deviation of the measured temperature, and may cause error or even failure of the Gleeble test. Based on our finite element method simulations, a correction scheme and equation are proposed.