Tribological Performance of Gas Tungsten Arc Welded Dissimilar Joints of sDSS 2507/N50 Steel

This study investigates and establishes the effect of welding process parameters on the tribological performance of the fabricated weld using the gas tungsten arc welding (GTAW) process. Both ER 2594 and ER 70S-2 were used as filler metals to fabricate a dissimilar GTA weld between sDSS 2507 and N50 steels. sDSS 2507/N50 DWJs have substantial importance to the subsea oil-gas drilling industries, especially in tubing and coupler assembly. The thermodynamic study predicts microstructure evolution during weld fusion zone cooling. Dry-sliding tribology behaviors were investigated using a pin-on-disc dry-sliding wear tester with a constant load of 30 N, sliding speeds from 1.111 to 6.666 m/s, and distances from 500 to 3000 m. Scanning electron microscopy examined the worn surface's wear mechanism and progression. ER70S2-LHI specimen had the lowest volume loss (12.83 mm3), and the N50 BM exhibited the greatest (112.65 mm3). Due to its martensitic structure, ER70S2-LHI has the lowest wear rate (4.28 x 10-3 mm3/m), while N50BM demonstrates the highest wear rate (37.5 x 10-3 mm3/m). For both LHI and HHI weld conditions, ER70S2 filler welds outperform ER2594 filler welds by 85 and 60%, respectively, in volume loss and by 81 and 48%, respectively, in wear rate. N50 BM had poorest wear progression and the ER70S2-LHI weld zone the most. Sliding wear on pins from base metal and filler weld zones exhibits mixed-mode abrasive, adhesive, and fatigue wear, producing material removal as spalling and flaking.