“…In 12 mm thickness plates, it is to be expected that PWNT treatment would yield much higher impact toughness with the more homogeneous microstructure and uniform hardness portrayed across the weld joint compared to PWDT treatment. In fact, the detailed studies on sub-size Charpy (55 mm x 10 mm x 5 mm) samples machined from 6 mm thick FSW joints have demonstrated the superior impact toughness values in the PWNT state compared to those recorded in PWDT state [11]. Figure 13 Fractographs of impact tested samples for 500 and 900 rev min −1 conditions revealing cleavage fracture in as-welded state (a,b) and ductile fracture for PWDT condition (c,d), respectively.…”
Section: Resultsmentioning
confidence: 99%
“…The lack of grain boundary carbides would lead to poor creep resistance with associated premature intergranular cracking. In view of this, post-weld heat treatments (PWHTs) have become absolutely essential to bring down the high hardness developed in these zones and also to re-precipitate the grain boundary strengthening carbides [11]. However, in a study conducted on F82H steel employing a low rotational speed on a sheet of 1.5 mm thickness, it has been noticed that the weld and BM zones display similar hardness and microstructure, leading to a conclusion that the PWHT may not be necessary for FSW joints [12].…”
Full penetration friction stir welding was conducted on 12 mm thick reduced activation ferritic-martensitic steel at tool rotational speeds of 500 and 900 rev min −1 . Comparator welds at 500 rev min −1 were also produced in 6 mm thick reduced activation ferritic-martensitic steel plate to evaluate section thickness effects. Increase in section thickness led to an increase in heat input, which strongly influenced the microstructure evolution in stir zone (SZ), thermomechanical affected zone and the overall hardness in the SZ of this steel. In the as-welded condition, the base metal microstructure was significantly altered and resulted in carbide-free grain boundaries. The desirable microstructure and mechanical properties were achieved by subjecting the as-welded joints to appropriate post-weld heat treatments.
“…In 12 mm thickness plates, it is to be expected that PWNT treatment would yield much higher impact toughness with the more homogeneous microstructure and uniform hardness portrayed across the weld joint compared to PWDT treatment. In fact, the detailed studies on sub-size Charpy (55 mm x 10 mm x 5 mm) samples machined from 6 mm thick FSW joints have demonstrated the superior impact toughness values in the PWNT state compared to those recorded in PWDT state [11]. Figure 13 Fractographs of impact tested samples for 500 and 900 rev min −1 conditions revealing cleavage fracture in as-welded state (a,b) and ductile fracture for PWDT condition (c,d), respectively.…”
Section: Resultsmentioning
confidence: 99%
“…The lack of grain boundary carbides would lead to poor creep resistance with associated premature intergranular cracking. In view of this, post-weld heat treatments (PWHTs) have become absolutely essential to bring down the high hardness developed in these zones and also to re-precipitate the grain boundary strengthening carbides [11]. However, in a study conducted on F82H steel employing a low rotational speed on a sheet of 1.5 mm thickness, it has been noticed that the weld and BM zones display similar hardness and microstructure, leading to a conclusion that the PWHT may not be necessary for FSW joints [12].…”
Full penetration friction stir welding was conducted on 12 mm thick reduced activation ferritic-martensitic steel at tool rotational speeds of 500 and 900 rev min −1 . Comparator welds at 500 rev min −1 were also produced in 6 mm thick reduced activation ferritic-martensitic steel plate to evaluate section thickness effects. Increase in section thickness led to an increase in heat input, which strongly influenced the microstructure evolution in stir zone (SZ), thermomechanical affected zone and the overall hardness in the SZ of this steel. In the as-welded condition, the base metal microstructure was significantly altered and resulted in carbide-free grain boundaries. The desirable microstructure and mechanical properties were achieved by subjecting the as-welded joints to appropriate post-weld heat treatments.
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