FORMATION OF WELD METAL STRUCTURE IN ELECTRON BEAM WELDING OF SINGLE CRYSTALS OF HIGH-TEMPERATURE NICKEL ALLOYS

摘要

Investigations of the features of temperature-rate parameters of weld pool metal solidification in EBW of single crystals of high-temperature nickel alloys were the basis for establishing the peculiarities of their influence on ensuring the single-crystal structure. Investigations were performed on single-crystal samples of commercial high-temperature nickel alloy JS26 with application of methods of thermometry of liquid pool melt during weld metal solidification at cooling. The structures were studied with application of methods of microprobe analysis, optical and electron metallography and XRD. A computational-experimental procedure for determination of temperature-rate parameters of weld metal solidification is proposed, the nature of their variation across weld pool solidification front is shown, and the interrelation with the welding modes is established. The range of parameter values was determined, in which grains with random crystallographic orientation form in the weld. The possibility of controlling the structural perfection of weld metal through optimization of temperature-rate parameters of solidification is shown.