Fatigue Crack Growth Data for Steel n-a-Xtra 56. Part 2. Weld Metal and Heat Affected Zone

摘要

Fatigue crack growth data were obtained for the weld metal and for the heat affected zone at three different R-values (R = 0.2, 0.5 and 0.8) of wind turbine rotor steels. It is found that although at higher crack growth rates cracks may grow faster in weld metal and heat affected zone than in base material, the near-threshold crack growth rates are slower in weld metal and heat affected zone than in base material. This is beneficial for the overall lifetime of the wind turbine since cracks are likely to initiate at welds and the near-threshold regime largely determines the fatigue behavior, due to the large number of load cycles the turbine blades are designed to sustain during their required safe service life of 30 Yr.