A method of forge welding includes placing at least two components for welding together, adjacent each other and with an exothermic flux mixture placed between the components. The exothermic flux mixture is heated to initiate an exothermic reaction and the faying surfaces of the two components are pressed together. The components being welded may be tubular, in particular pipes. Apparatus for the method of forge welding and exothermic flux mixtures for the method of forge welding are also provided.

A flux (55) for superalloy laser welding and additive processing (20, 50), including constituents which decompose when heated in a laser induced plasma or to a melt temperature of the superalloy (42), creating one or more gases (46) that blanket the melt to protect it from air, while producing not more than 5 wt. % of slag relative to the weight of the flux. Embodiments may further include compounds providing one or more functions of surface cleaning, scavenging of impurities in the melt, and elemental additions to the superalloy.

A method of fabricating a joining preform includes the step of printing a self-fluxing joining alloy. Joining includes brazing and soldering. The self-fluxing joining alloy contains at least one of phosphorus, boron, fluorine, chlorine, or potassium. Another printing step prints a non-phosphorous joining alloy. Both printing steps are performed by an additive manufacturing or 3D printing process. The printing a self-fluxing joining alloy step may be repeated until the non-phosphorous joining alloy is substantially encapsulated by the self-fluxing joining alloy. The self-fluxing joining alloy may be a BCuP alloy, a CuP alloy, a CuSnP alloy, a CuSnNiP alloy or a CuAgP alloy. The non-phosphorous joining alloy may be a BAg alloy, a BNi alloy or a BAu alloy.