Method of improving fatigue life of cast nickel ba

专利名称：Method of improving fatigue life of cast

nickel based superalloys and composition

发明人：Allen F. Denzine,Thomas A. Kolakowski,John

F. Wallace

申请号：US05/672350申请日：19760331公开号：US040751A公开日：19780314

摘要：The invention consists of a method of producing a fine equiaxed grain structure(ASTM 2-4) in cast nickel-base superalloys which increases low cycle fatigue lives withoutdetrimental effects on stress rupture properties to temperatures as high as 1800° F.These superalloys are variations of the basic nickel-chromium matrix, hardened bygamma prime Ni.sub.3 (Al, Ti)! but with optional additions of cobalt, tungsten,

molybdenum, vanadium, columbium, tantalum, boron, zirconium, carbon and hafnium. Theinvention grain refines these alloys to ASTM 2 to 4 increasing low cycle fatigue life by afactor of 2 to 5 (i.e. life of 700 hours would be increased to 1400 to 3500 hours for a givenstress) as a result of the addition of 0.01% to 0.2% of a member of the group consistingof boron, zirconium and mixtures thereof to aid heterogeneous nucleation. The alloy isvacuum melted and heated to 250°-400. degree. F. above the melting temperature,cooled to partial solidification, thus resulting in said heterogeneous nucleation and finegrains, then reheated and cast at about 50°-100° F. of superheat. Additions of 0.1% boronand 0.1% zirconium (optional) are the preferred nucleating agents.

申请人：UNIVERSITY PATENTS, INC.

代理机构：Fay & Sharpe

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