A TWI team has helped an Industrial Member to satisfy test specifications set by its client - a leading petroleum company. Following a series of CTOD tests carried out at Abington, TWI was able to make recommendations for improving the toughness of weldments used on the client's accommodation platform.
CTOD tests were required on welds used for joining thick parent steel plates. Two types of weld made with self-shielded, flux-cored wire, were produced in 63mm thick material using the stringer bead technique. The first type was produced in the flat position while the second type, intended for HAZ specimens, was made in the horizontal-vertical position. The second side of both welds was produced in the overhead position.
CTOD testing was carried out in three point bending at -10◦C in accordance with the British Standard test method using a universal servo-hydraulic test machine. HAZ specimens were sectioned after testing so that their microstructure could be sampled at the fracture initiation site.
Results showed that fracture toughness could be improved by increasing travel and wire feed speeds. Additional benefits could be achieved by using a V joint geometry for production welding to avoid weld beads being deposited directly on top of existing weld beads.
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