Friction stir welding of 6 mm thick carbon steel underwater and in air

Abstract

This study compared the mechanical and microstructural properties produced during friction stir welding (FSW) of S275 structural steel in air and underwater. Post weld tests assessed the tensile strength, micro-hardness, distortion, Charpy impact toughness and fatigue performance in each case. The study showed that there was no significant difference in the strength, hardness or fatigue life of the air and underwater specimens. However, Charpy impact toughness was shown to decrease for the underwater specimens and was attributed to the presence of a slightly less angular grain structure than the samples welded in air. Reduced angular and longitudinal distortion was observed in the underwater welded plate compared to the plate welded in air.

Evolution of Microstructure During Double-Sided Friction Stir Welding of Microalloyed Steel

“…[16] Depending on the FSW parameters, others recorded very fine lamellae pearlite colonies [9] or 'pearlite fractured into small pieces.' [29] This break-up of constituent particles was particularly evident in the FSW of 6 mm thick carbon steel investigated by Baillie et al [30] and has also been noted in FSW of Al359-20 pct SiC MMC, which showed visible particle clusters and particle-free regions in the as-extruded composite. [31] Both Shindo et al [31] and Ma et al [32] reported that after FSW, the distribution of SiC particles was improved and the amount of finer SiC particles in the NG zone was significantly increased, due to intense plastic deformation and materials mixing.…”

“…This has manifested itself as a 10 pct reduction in the heat input, which was calculated from processing factors such as travel speed, tool rotation speed, and torque. [19] The samples were taken from the areas of relative stability within the welded regions, i.e., out with the first and last 100 mm.…”

Study of Influence of Temperature Variation in Hot Sink Underwater Friction Stir Welding Of 4 mm Thick AA6061 Plate and Corrosion Study

“…al. [4] studied about the comparison of the mechanical and microstructural properties produced during friction stir welding of S275 structural steel in air and water. .…”

Dissimilar friction stir welding of duplex stainless steel to low alloy structural steel

“…Also presented (Fig. 3b) is the top surface at the edge of the weld at the RT side where a surface breaking non-metallic inclusion is present; such inclusions 34 were not identified in all microscopy samples and those that were had an approximate 0.25 mm penetration depth. Such inclusions created a discontinuity in the weld's top surface and were reported to be primarily oxide scale with traces of paint primer 34 since the plates received no prior preparation.…”

“…For these reasons, work was initiated to establish and assess the feasibility of joining dissimilar materials using friction stir welding (FSW). [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Extensive work has been carried out to demonstrate the advantages of FSW for a range of metals [24][25][26][27][28][29][30][31][32][33][34][35][36] and a growing amount of work for dissimilar alloys. 1,[8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Results from FSW of dissimilar materials highlighted the viability of such a process with the majority of reports concluding that high quality, defect-free welds had been produced.…”