Prominence of Narrow Groove on Pulsed Current GMA and SMA Welding of Thick Wall Austenitic Stainless Steel Pipe

The pulsed current gas metal arc (PGMA) welding and shielded metal arc (SMA) welding with a narrow groove joint were used to weld the thick wall 304LN stainless steel pipe. The primary emphasis has been laid on the welding procedure by reducing the weld area with a narrow groove design. A constant heat input of 7.5 +/- 0.5 kJ/cm was used to perform the narrow gap SMA and PGMA welding of austenitic stainless steel pipe. The PGMA welding was carried out at two different phi of 0.05 and 0.25 and groove width of 15 and 11 mm. The obtained results have shown that the narrow groove PGMA welds prepared at relatively lower Omega having 4-7% delta-ferrite content are comparatively less prone to solidification cracking than the SMA weld joint. The amount of porosity content was marginally increased in PGMA welds, whereas in the narrow groove SMA welds, the amount of porosity and inclusion content got increased by almost 30%. The narrow groove PGMA welds have significantly higher yield strength in both the longitudinal (363 MPa) and circumferential (466 MPa) directions than the SMA weld joints. Narrow groove PGMA welds have appreciably better Cv-impact toughness (126 J) and lateral expansion (2.5 mm) than that observed in SMA weld joint. The narrow groove PGMA weld (11 mm weld width) of various phi of 0.05 and 0.25 show widespread ductile fracture behavior with fine dimples and significantly minor porosity content than the SMA weld joints. The PGMA welds are comparatively less scattered in hardness across the weld and HAZ at both the Omega and phi levels.