Study into the effect of different energy sources on the structure and mechanical properties of EP693 nickel alloy weld joint

Abstract

The paper provides the results of a study on the influence of welding types (laser, electron beam, and TIG welding) on the properties of a permanent connection made of an EP693 alloy of the Ni–Cr–W–Co–Mo system used in the production of gas turbine engine components and parts. EP367 filler wire of the Ni–Mo–Cr–Mn system was used to obtain a weld during laser and TIG welding. A comparative analysis of heating areas and power densities was performed for the welding types studied. It was established that TIG welding features by greater values of the heating area and power density in comparison with laser and electron beam welding. It was found that the type of welding affects the features of weld formation. For example, a weld is formed with the transition to knife fusion penetration in the weld root for electron beam welding, and in the form of an «hourglass» for laser welding. The analysis of the heat affected zone microstructure showed that the smallest grain size is formed during laser welding. The distribution of elements in the weld joint was analyzed. It was found that when welding with the use of filler wire, the Mo content increases and the W, Co, Al, and Ti content decreases in the weld and heat affected zone relative to the base metal. This determines the peculiarities of failure for samples obtained using the welding types studied. Samples obtained by TIG and laser welding broke along the heat affected zone on the weld reinforcement side. Samples obtained by electron beam welding broke along the weld. Mechanical tests of samples at room and elevated temperatures showed that samples obtained by laser and electron beam welding have the highest tensile strength.