Results and discussion
The strain controlled cyclic test results showed that the load carrying capacity of the cross-weld specimen was comparable to that of the base metal. Static test results in the literature [20] presented in Table 1, showed that the strength of weld section and heat affected zone were both slightly higher than the base metal but such behaviour was not noticed in the cyclic test performed in this study. This can be explained by the cyclic softening behaviour (Fig. 7) observed within the first 20 cycles in this study. Strain controlled test leads to application of plastic strains to the material, i.e. the material is deformed well beyond the yield strength. Since a stress plateau region is characteristic of metals due to work hardening, the difference in the behaviour of the cross-weld specimen and base metal specimen becomes negligible. Moreover, the application of cyclic loads causes the stress to relax in consecutive cycles owing to the Bauschinger effect. Therefore, the experimental results obtained from this study indicate that the cyclic deformation behaviour of circumferential welds employed in OWT structures can be predicted using the base metal material properties.