Abstract
In evaluation of materials for arctic applications, their low temperature properties are addressed. The heat affected zone toughness has been shown to be critical with respect to satisfactory fracture toughness. Less attention has been given to the weld metal. Therefore, the present study was initiated with the objective to assess the fracture toughness of weld metals deposited with different welding wires. Both impact and fracture toughness testing were included; the latter one considered testing of full sized single edge notch bending specimens with through thickness notch in the weld metal and sub-sized specimens with surface notch in primary weld metal and in re-heated weld metal. The testing was performed at -60ºC and three parallels were run for all configurations.
The results showed that both the Charpy V notch and fracture toughness varied substantially between the different welding wires employed. For the Charpy case, impact properties scattered from about 20 J for Weld 3 to 75-115 J for Weld 5. This ranking changed when it comes to full size CTOD specimens. Still Weld 3 had lowest values, while Welds 1 and 2 appeared with best toughness. The behaviour of Welds 1 and 2 was also different from the other welds regarding sub-sized samples with notches in the primary and reheated weld metals. Here, Welds 1 and 2 had similar toughness for the two weld metal regions, while Welds 3, 4 and 5 had higher CTOD values for the reheated weld metal. These results are discussed in terms of the weld metal microstructure observations.
The results showed that both the Charpy V notch and fracture toughness varied substantially between the different welding wires employed. For the Charpy case, impact properties scattered from about 20 J for Weld 3 to 75-115 J for Weld 5. This ranking changed when it comes to full size CTOD specimens. Still Weld 3 had lowest values, while Welds 1 and 2 appeared with best toughness. The behaviour of Welds 1 and 2 was also different from the other welds regarding sub-sized samples with notches in the primary and reheated weld metals. Here, Welds 1 and 2 had similar toughness for the two weld metal regions, while Welds 3, 4 and 5 had higher CTOD values for the reheated weld metal. These results are discussed in terms of the weld metal microstructure observations.