INFLUENCE OF MULTI-PASS GTAW PARAMETERS ON MICROSTRUCTURE CHARACTERIZATION AND MECHANICAL PROPERTIES OF SAF 2507 SUPER DUPLEX STAINLESS STEEL

Document Type : Original Article

Authors

1 Mechanical Engineering Dept., Faculty of Engineering, Suez Canal University, EGYPT

2 Department of Metallurgical and Materials Engineering, Faculty of Petroleum and Mining Engineering, Suez University, Suez 43512, Egypt

3 Mechanical Engineering Dep., College of Engineering at Al Kharj, Prince Sattam Bin Abdulaziz University, Al Kharj 16273, Saudi Arabia

4 Siemens-energy Company, Cairo, Egypt.

Abstract

In the present work, a 6 mm thickness SAF 2507-SDSS were welded by multi-pass gas tungsten arc welding (GTAW) process with ER2594 electrode using different heat inputs. Microstructure and mechanical properties of SAF 2507 joints obtained from multi-pass GTAW processes were investigated. The obtained joint was evaluated and characterized by using visual inspection, radiographic test, liquid penetrant test, optical microscopy, scanning electron microscopy, tensile and hardness test. The results obtained have shown that the type of filler electrode, heat input, and interpass temperature are the controlling factors in achieving a sound weld joint. The multi-pass GTAW of 2507 SDSS exhibited an enhancement in both hardness and yield strength compared to the base metal. In the welded zone, there were three distinct forms of austenite: Widmanstatten austenite (WA), intra-granular austenite (IGA), and grain boundary austenite (GBA), along with the presence of ferrite.  The number of welding passes and heat input had a significant impact on the α:γ ratio. The content of ferrite in the welded zone is relatively close to the equilibrium ratio of the base metal and did not exhibit significant fluctuations when employing various welding parameters.

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