Friction welding of dissimilar metal joints with intermediate layers

Purpose: Metals such as titanium, vanadium, zirconium, niobum, molybdenum and also tantalum and tungsten must be protected at elevated temperatures from the effects of oxygen, nitrogen and hydrogen. For this reason, it is of interest, both from the innovative and practical points of view, to investigate the possibility of using the process of friction welding to produce joints in these materials. Design/methodology/approach: Investigations were made on the pseudoalloy of tungsten of D18 type an alloy produced by a powder-metallurgy method of sintering tungsten grains, which form the matrix (95% by weight), with the bonding phase formed by Ni-Fe alloy. Findings: In the course of the direct friction welding of dissimilar metal joints in niobum and titanium with steel and D18 pseudoalloy of tungsten, hard intermetallic phases are formed which cannot be removed from the whole area of the joint. The use of interlayers of metals, which in the solid state do not form intermetallic phases with the metals of the joint, ensures the absence of microcracking in the joint. For the steel-niobum, or D18 pseudoalloy of tungsten-niobum joints, an interlayer of copper can be used, but for joints with titanium an additional vanadium layer is required. Research limitations/implications: In the case of a joint made in niobum and D18 pseudoalloy of tungsten there is a possibility of intermetallic phases being formed between Nb and bonding elements - Fe and Ti. A very hard zone is formed with many microcracks so further investigations are needed. Originality/value: The possibility of using the process of friction welding to produce joints in these materials.