TG6: 3-Pass Slot Weld (Ni alloy)

The Task Group 6 (TG6) round robin specimen is closely based upon the TG4 design, except that it is fabricated from nickel based alloys, namely Alloy 600 plate with Alloy 82 weld metal. It thus presents all the advantages and challenges of the TG4 specimen, namely, the generation of a complex 3D residual stress distribution in a compact, portable specimen that is amenable to rapid measurement of residual stresses by diverse techniques, with a significant volume of weld metal that undergoes multiple high temperature thermo-mechanical cyclic loads. The use of nickel-based alloys then adds considerable residual stress measurement challenges, while the slightly overmatched weld in AISI 316 is replaced by a significantly undermatched weld in alloy 82. The TG6 specimen is a 3-pass slot weld in Alloy 600 plate, made using a Tungsten-Inert-Gas welding process. The dimensions of the plate are 200 x 150 x 12 mm3, while the slot is 76 mm long and 5 mm deep, and is filled with three superimposed weld passes. As it was done in Task Groups 1 and 4 before, NeT Task Group 6 is undertaking parallel measurement and simulation round robins.

Fig. 1. TG6 – engineering drawing of specimen

Fig. 2. TG6 – macrograph of fusion zone

Fig. 3. TG6 – pad of weld material for the generation of weld specific materials data

Fig. 4. TG6 – through thickness distribution of longitudinal residual stresses, simulation result compared to average of measurements

Fig. 5. TG6 – quantifying impact of gauge volume centre of gravity shift through attenuation

Fig. 6. TG6 – through thickness distribution of transverse residual stresses, simulation result compared to average of measurements

Fig. 7. TG6 – Gleeble testing, measurements of several thermos-mechanical load cycles compared to the corresponding simulations of the material response