PSI - Issue 60

Cyril Reuben Raj et al. / Procedia Structural Integrity 60 (2024) 709–722 Cyril Reuben Raj / StructuralIntegrity Procedia 00 (2024) 000 – 000

720

12

4 5 6

SSHAZ-T41 SSHAZ-T42 SSHAZ-T42

SMAW GTAW SMAW

434

617

79.1

409.81 444.86

633.95 640.24

83.01 77.05

Fig. 12. Stress strain curves of as-welded and thermal aged weld tensile specimens along the heat affected zone: (a) GTAW zone and (b) SMAW zone. 4. Conclusion Effect of thermal aging on austenitic stainless steel welds with ferrite content was studied. Thermal aging at temperature 400 ℃ f or 10,000 and 20,000 hrs was carried out. The micro-structural examinations, micro and macro hardness measurements and tensile tests were carried out. Following are the conclusions of the study: 1) Ferrite content in the SMAW and GTAW zones ranges in between 3.3 to 4.8FN and 4.4 to 10.5 FN respectively. Ferrite presence assures prevention of hot cracking welding of SS304LN material. However, these ferrite present in the weld joints after welding may lead to low temperature thermal ageing embrittlement when weld joints is subjected to operating temperature (approx 300-400 ℃ ). 2) Microstructural examinations assures the presence of austenite phase and ferrite phase as vermicular and lath morphology. Inclusions have also been observed in the austenite phase.