Focussed arc tungsten inert gas brazing of zinc-coated steels

Abstract

The brazeability of automotive zinc-coated steels depends on several factors. These include the morphology of the joint and the welding parameters selected. However, more fundamental material factors such as the composition of the coating, method of coating and coating thickness also have a significant effect. In this study, five commercially available and widely used automotive zinc-coated steels are investigated to assess brazeability. Surface zinc content and the coating type are shown to have a marked effect on the quality of the resulting joint. This is shown by surface analysis of the joint to determine evenness and bridging capability of the filler material and a cross-sectional analysis of the joints. Differences in wettability and contact length of the filler material and zinc-coated steel substrate are observed. It was found that electro-galvanised steel exhibited the best brazeability of the materials investigated here. Wettability of spreading angles as low as 17.3°, most uniform contact length and best bridging capability due to the filler material forming a metallic bond with the substrate were observed. However, pores were present in cross-sections. Galvannealed steel also showed good wetting with no embedded defects. Other steels used (galvanised and magnesium-aluminium zinc steels) presented problems with uniformity, high spreading angles of the filler material and poor bridging characteristics.

An experimental and numerical investigation on the process efficiency of the focused-tungsten inert gas welding of Inconel 718 thick plates

“…The arrangement avoids thermal stresses in the nozzle and the consumption of extra energy to cool the nozzle by focusing the plasma far from it, raising the efficiency of the process compared with the conventional arc processes. 20…”

“…The arrangement avoids thermal stresses in the nozzle and the consumption of extra energy to cool the nozzle by focusing the plasma far from it, raising the efficiency of the process compared with the conventional arc processes. 20 Three sets of experimental tests were conducted, and the findings were used in conjunction with numerical analyses for the aims summarized in Table 2.…”

On the interaction between welding residual stresses: A numerical and experimental investigation

“…A conventional TIG torch floods the area with a shielding gas to avoid oxidisation upon solidification. Whereas the focussed arc TIG has a reduced gas exit nozzle, which uses the shielding gas to help shape the plasma, and increase the power density through a focussing effect [9]. The welds were autogenous, i.e.…”

Dissimilar vacuum brazing of WC-Co and cold work steel utilizing a new near-eutectic silver-copper filler alloy

“…[5][6][7][8][9][10] Previous studies reported many techniques of joining tungsten carbide and metals, including ultrasonic welding, [11][12][13][14][15] diffusion bonding [15][16][17][18] and brazing. [18][19][20][21][22][23][24][25][26][27] Brazing is a very promising technique to join the dissimilar parts. Brazing is a high-temperature joining process utilizing filler material to produce powerful joints, even between dissimilar metals.…”