| Abstrakt: |
This research investigates the mechanical characteristics and fracture location associated with a similar welding process of T91 using Gas Tungsten Arc Welding (GTAW). Two different filler materials configurations are used, including (ER90S-B9) and (ERNiCr-3). Experimental work was carried out to validate the mechanical properties at a higher temperature (550 °C), and mechanical tensile strength was evaluated. Microstructures of welding joint and heat affected zone are identified via scanning electron microscope (SEM) images. A set of thermal treatment processes were applied, such as pre-welding heat treatment at 200 °C, the inter-pass temperature of 300 °C, and post-welding thermal treatment at 740 °C for 15 minutes. The major work findings revealed that the ultimate strength corresponding to the welding using the filler material ER90S-B9 was 547 MPa, related to an elongation of 17%. While the ultimate strength of the welding was 521 MPa, corresponding to an elongation of 13% and cross-section of 58.86 mm2. Furthermore, findings indicated that the hardness values associated with ER90S-B9 welding range between 252 and 298 HV. While the hardness of welding using the filler material ERNiCr-3 ranges between 204 and 321 HV. Additionally, it was found that although (ERNiCr-3) is more expensive than (ER90S-B9), the latter filler material provided better welding performance, including higher hardness, ductility, and toughness than (ERNiCr-3). Also, the welding process resulted in the precipitation of Cr, Mo, and Fe, which formulated M23C6. Besides, using (ERNiCr-3) helped austenite form at the welded joint resulting in a reduction of welding joint hardness. Besides, results affirmed that the fracture location took place at the base metal when the ER90S-B9 was used. While the fracture location using the filler material ERNiCr-3 occurred at the weld metal. [ABSTRACT FROM AUTHOR] |
