Mechanical properties of SMA- and SA-welded joints in a steel RAEX 386 P arctic

The report gives the test results on mechanical properties of shielded metal arc and submerged are welded joints of normalised steel Raex 386 P Arctic (E StE 355). The joints were tested using conventional hardness, tensile and Charpy-V testing as well as fracture testing. The test results of the welded joints showed reasonably good strength and toughness properties as compared to those of the base material. The ductile-brittle transition behaviour of the joints welded with the arc energies of 17,30 and 50 kJ/cm was, however, found to be located at considerably higher temperatures (in the range of -15 °C to -60 °C) than that of the base material (-60 °C to -80 °C). The Ni-alloyed SMA-welds showed sharper transition behaviour than did the Mn-Si-alloyed SA-welds. On the other hand, the transition temperatures of the fusion boundaries were lower in the SAW-tests than in the SMAW-tests carried out with the same arc energy. The Kj-test results showed that the arc energy should be kept low (~17 kJ/cm) to achieve good fracture toughness properties in welded joints of the steel Raex 386 P Arctic. The SMA-welds showed somewhat more brittle fracture behaviour than did the corresponding SA-welds. A probable explanation for this is inhomogenity in the SMA-welds, which probably results from weaving used in the SMAWtests. The influence of arc energy on the toughness was found to be more pronounced in the fracture mechanics tests than in the Charpy-V tests. This is probably due to the use of full thickness test specimens in the fracture mechanics tests, in which the fracture toughness is also affected by the properties in the weld root. This effect is not seen in the Charpy-V tests, the specimens of which were taken from the surface area of the joints.