Design of new selfjigging temperature–time–gap width test specimen

The design and use of a novel temperature–time–gap width (TETIG) test specimen to characterise brazing alloys is described. The assembly was constructed from longitudinally sectioned bar(s) of the parent material(s), with outer segments of the two halves providing datum surfaces for the selfgapping system, conveniently bound in place with wire. Gap filling took place from alloy reservoirs in two machined grooves and flow could be chosen to take place from one or both, in a horizontal or vertical plane. Brazing alloys in the form of wire, sheet, paste, or powder can be used. The design overcomes a problem associated with conventional TETIG specimen design in which the effects of the flow distance of the molten filler metal are indistinguishable from the effects owing to the gap width of the joint. To investigate the reproducibility of the design, a Cu–Sn–Ni–Si–Ag alloy in both powder and solid forms was investigated in identical steel assemblies. Results which led to the use of the specimen design in the development and assessment of an improved alloy composition are reported.