A few days ago, two sets of castings developed and manufactured by DHHI for 18MW offshore wind turbine successfully rolled off. These castings are hub and main frame, which, as the core components of offshore wind turbine, are complex in construction, large in overall size, up to a weight of 70 tons and a height over 6.5 meters for single part. They have to be capable of satisfying the 25-year life under severe offshore service condition, with very strict requirement in performances, and are very difficult for manufacturing.