a shear - assisted solid state welding method for joining of metal parts , involves a first step of heating opposing surfaces in a non - passivating environment to a temperature in the hot working temperature range of the metal . a second step involves bringing the opposing surfaces into contact while still in the hot working temperature range , and applying compressive stress sufficient to substantially prevent sliding in response to shear displacement , causing plastic flow in the hot layers . a third step involves imposing relative shear displacement of the metal work pieces without disengaging the opposing surfaces . the shear displacement induces plastic shear strain within the hot layers to progressively induce bonding .