GB568207A - Improvements in the reduction of metal articles to desired sizes - Google Patents

Abstract

568,207. Sand-blast. MOND NICKEL CO., Ltd., and PFEIL, L. B. May 21, 1943, Nos. 8119/43 and 7483/44. [Class 60] [Also in Groups II, XXII and XXXVI] In a process for fabricating metal articles by reducing their size by anodic dissolution, in order to prevent undesirable pitting of, and to expose flows in, the metal surface, the dissolution process is interrupted at least once and the surface abraded by shot-blasting, sand-blasting, grinding. In this way, larger amounts may be removed than is usual in known anodicdissolution polishing processes, and the process may replace or precede the last machining stage, such as rolling or forging. For example, a turbine blade may be roughly forged to shape, then processed by the means according to the invention, then forged to final shape and reduced to exact size by the process of the invention. When there is more than one interruption, the period of treatment before each one are increased successively throughout the process. Shaped cathodes or anode-shields may be employed for removing amounts which vary at different parts of the surface. The Specification gives numerical figures for shotblasting, degree of concentration of hydrochloric acid, and temperature and current density of the bath. For treating an 80/20 nickelchromium alloy, the electrolyte of Specification 526,854, [Group XXXVI], may be employed, namely 55 per cent by volume concentrated H3PO4, 27 per cent concentrated H2SO4' 18 per cent water, one process being specifically described as an example. Pickling may be employed to loosen every adherent scale before shot-blasting. A 2/1 nickel-copper alloy also is referred to.