FINITE ELEMENT ANALYSIS OF TEMPERATURE AND PHASE COMPOSITION OF TITANIUM ALLOY BY TIG WELDING

Abstract

Titanium and its alloys have been widely used in varied industries such as aerospace, automobile, marine, chemical, medical due to their high strength, corrosion resistance and toughness. One of the factors constraining the widespread use of titanium alloys is the high cost of titanium parts, which is associated with the technology of their manufacture and the relatively high cost of the raw materials used. Reducing the cost of products involves the development of alloys using cheap raw materials and such technological processes that provide higher efficiency in the use of consumed energy and materials. The most promising in terms of reducing the price is the creation of economically alloyed alloys with improved processability, since for titanium the cost of manufacture accounts for most of the total cost of parts. In recent years, lowcost alloyed titanium alloys are becoming more common, in which expensive alloying elements are replaced by inexpensive and accessible elements, such as iron, carbon, oxygen and nitrogen, but their weldability is still under heavy investigation. In this study a mathematical model of argon-arc welding with tungsten electrode of an economically alloyed titanium alloy Timetal LCB has been developed. To calculate the effect of welding mode parameters on the formation of a weld, a three-dimensional mathematical model of thermal processes in titanium was built for welding with a scanning heat source, which is based on the differential heat equation. Comparison of the calculation results with experimental data confirmed the adequacy of the developed mathematical model. Based on this model, the thermal fields in the welded joint are determined. Nowadays the finite element method (FEM) is a suitable method for simulation of the welding process phenomena. It is possible the prediction of weld geometry through the optimization of the welding parameters, FEM simulation can calculate the weld pool shape, thermal distortion, residual stress and metallurgical change for various combinations of welding parameters. In FEM simulation, one of the topics is the choice of the heat source parameters, which is paramount for a satisfactory representation of welding process.