STRETCH FORMING OF VERY LONG STAINLESS STEEL SKINS

Abstract : Precipitation hardening FV 520 stainless steel was stretch formed in the fully softened (austenitic) and the cold rolled and transformed (martensitic) conditions using the H.S.A. 250T stretching machine; the skins were subjected to various heat treatments after forming. It was shown that FV 520 skins up to at least 45 ft. long can be stretch formed satisfactorily in the soft condition only. Forming in the harder condition gave rise to considerable springback. Long skins of FV520 could be heat treated satisfactorily after stretch forming but low temperature transformation was impractical due to problems of distortion. (Author)