The investigation of welding zone of Ti6Al4V/Ti6Al4V alloy pair by use of pta welding method

It is difficult to weld the Ti6Al4V alloy welding pair by use of traditional fusion welding methods. This alloy particularly uses in chemical industry, aerospace and defense industries. This welding pair has been bonded by use of plasma transferred arc (PTA) method which is a new and improved manufacturing technique. The researches about weldability of Ti6Al4V alloy pair with PTA welding method are limited.PTA welding method is a protective gas arc transfer method. In this welding process an electric arc between the tungsten electrode and workpiece which melts metal consists. To achieve a high speed arc column at the copper nozzle, the mouth of nozzle has been narrowed. This method also can be used in the treatment of metal filler. Generally PTA welding method uses to weld different thicknesses of stainless steel, special materials such as tantalum and zirconium, aluminum alloys, titanium alloys, steel alloys, plain carbon steels, copper and nickel alloys. Today, PTA welding method uses in aerospace, nuclear, electronics, shipbuilding and many other branches of industry. This method involves not only the freedom and economy, it involves also the highest quality and dependability.In this study, Ti6Al4V welding pair has been joined without use of any interlayer material and with use of Ni metal as interlayer material together without open mouths and without use of an additional wire by PTA welding method. The microstructural changes and mechanical properties of alloys after welding process parameters have been investigated optical microscopy and SEM images. In the welding zone intermetallic phases formed have been determined by EDS and XRD analysis. Mechanical properties of welded joint were determined by tensile strength test method and fatigue test method. The microhardness of joints has been carried out by microhardness tests. As result, it has been found, that to improve a best quality the working parameters must be well regulate.This PhD thesis consists of six chapters. The first chapter has been made an introduction, the second chapter has been given the actual literature. The third chapter has been given information about titanium and its alloys, information about the PTA welding and information about the fatigue strength of welded joints. The fourth chapter has been given information about the experimental studies and part of the preparation methods. The fifth chapter has been given experimental studies and the sixth chapter has been given the results of study.