Friction stir welding of thin DH36 steel plate

Abstract

A series of 4, 6 and 8 mm DH36 steel welds were produced using optimum conditions for friction stir welding (FSW). Comparator welds in the same thickness from the same plates were produced using a single sided single pass process submerged arc welds (SAW). This work was carried out to evaluate the mechanical properties of FSW material with a view to its possible application in a shipbuilding production process route. Overall, the performance of the FSW material was superior to the SAW comparators. Areas such as distortion and fatigue were particularly positive in the FSW material. An 8 mm thick plate was also produced using two FSW passes, one from either side, and it was found to have superior toughness and fatigue performance when compared to the single sided 8 mm FSW material. Some of these benefits are thought to have originated from the internal overlap zone between the two passes.

Fatigue Assessment of Friction Stir Welded DH36 Steel

“…An acicular shaped ferrite microstructure is observed in the thermo-mechanically affected zone (TMAZ), consistent over the mid-thickness of all FSW samples, whereas SAW samples present a typical acicular ferrite microstructure defined around proeutectoid ferrite grains [6]. The SAW plates present substantially more distortion than the FSW plates of the same thickness, and impact toughness levels for FSW and SAW samples are similar and within classification society impact requirements.…”

“…The SAW plates present substantially more distortion than the FSW plates of the same thickness, and impact toughness levels for FSW and SAW samples are similar and within classification society impact requirements. A relatively limited fatigue testing programme demonstrates that FSW samples exhibit better fatigue performance than the SAW samples of equivalent thickness [6].…”

“…Although material property data are gradually being generated for FSW of low alloy steel, the relevant publications evaluating its behaviour under fatigue loading are very limited; one noteworthy study [6] is evaluating the technical potential of FSW as a shipbuilding welding process and how it compares to submerged arc welding (SAW) of DH36 steel. An acicular shaped ferrite microstructure is observed in the thermo-mechanically affected zone (TMAZ), consistent over the mid-thickness of all FSW samples, whereas SAW samples present a typical acicular ferrite microstructure defined around proeutectoid ferrite grains [6].…”

Segregation of Mn, Si, Al, and Oxygen During the Friction Stir Welding of DH36 Steel

“…In another paper by the same authors [2] on mathematical modeling of the FSW process using computational fluid dynamics (CFD) technique, they reported that a maximum temperature of 1250°C was computed when the rotational and traverse speeds were 500 RPM and 400 mm/min, respectively. A comparison between FSW and submerged arc welding (SAW) of DH36 showed microstructure and mechanical properties improved as a [3]. Advantages of FSW of DH36 steel were also studied [4] by relating welding parameters to mechanical properties.…”

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

“…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.…”