Wind power generation equipment service life is 20 years, which is equivalent to the wind tower will withstand 109 alternating load. In addition to the fatigue load, wind towers will also withstand the stress caused by the temperature difference between the climate abrupt change. In the winter season, and will withstand the test of the low temperature. Therefore quite high performance of the wind towers of steel and its Welding Materials joints, not only should have sufficient strength, and there should be a good low-temperature impact toughness and fracture toughness.
Structural steel wind tower
The force of the wind tower structure condition and stress distribution characteristics, its structural components can be divided into the following three categories:
1) the particular structural element, is subject to high stress parts such as a cylinder flange.
2) of the main structural elements, normal force components, such as wind tower cylinder.
3) a secondary structural element, is a low-stress components, such as poles and other accessories.
For the special structural elements that require the use of a particularly low content of impurities such as sulfur, phosphorus and hydrogen steel, and to ensure that in the thickness direction of the steel material having sufficient plasticity. The steel intensity level reaches the yield strength of 275MPa. Base metal and Stainless Steel Electrodes joints districts -40 ° C V-notch impact toughness ≥ 50J, and applied CTOD (fatigue crack opening displacement) test. Recommended the following EN10225 standard steel wind tower construction in accordance with EC regulations: S355G8 + M S355G8 + N, S355G10 + M S355G10 N, S420G2. + Q S420G2 + M, S460G2 + Q, S460G2 + M.
For the requirements of the main structural elements of steel, in addition to the performance of the plate thickness direction, is similar to the other with the above-mentioned special steel for structural elements. Accordance with EC standards, the carbon content of the steel should be ≤ 0.14% ≤ 0.43% carbon equivalent CEV -40 ° C V-notch impact energy shall be ≥ 50J. Boat built and regulations of Germanischer Lloyd, -40 ° C V-notch impact energy longitudinal samples ≥ 34J transverse specimens ≥ 24J. Recommended for the main structural elements, the following comply with EN10255 standard steel: S355G7 + M, S335G7 + N, S355G9 + M, S355G9 + N, S420G1 + Q, S420G1 + M, S460G1 + Q, S460G1 + M.
Steel thickness of 25 ~ 50mm, the secondary structural member, allows use of the following levels: S355G6 + m, S355G3 + N and S355J2G3.
For the special structural elements and the main structural elements of steel, when the thickness of ≥ 40mm, the mills should provide users with the experimental results of the weldability of the steel sheet of the batch, to confirm its suitability in the various use state.