Accession Number : ADA139290

Title :   A Study of Fatigue Crack Propagation in Powder Metallurgy Hot Isotatically Pressed Nickel-Base Alloy.

Descriptive Note : Annual rept. 1 Jan-31 Dec 83,


Personal Author(s) : Hertzberg,R W

PDF Url : ADA139290

Report Date : 31 Jan 1984

Pagination or Media Count : 11

Abstract : Initial efforts were addressed at the preparation of powders that would result in the development of HIP'd logs possessing a large range of grain sizes and grain size distributions. After several trials, it was determined that the widest range of alloy grain size could be obtaining by using different HIPing temperatures in conjunction with different solution treatments (ST). The following treatments and grain sizes are identified: (1107 C HIP + 1121 C ST (ASTM No. 13)); (1107 C HIP + 1149 C ST (Duplex size ASTM average 8-9); (1107 C HIP + 1177 C ST (ASTM No. 6-6.5)); (1246 C HIP + 1149 C ST (ASTM No. 4)). Further aging treatments are planned at 650 C and 800 C to obtain fine and coarse gamma precipitate sizes, respectively. Initial fatigue crack propagation tests were completed with both material and computer-controlled test system performing in a well behaved manner. Crack closure measurements were obtained which allowed crack growth rate data to be compared with delta K sub eff. Grips and fixtures have been designed and ordered which will permit cyclic strain experiments to be conducted at both room and elevated temperatures. Techniques were developed to prepare thin foils to allow for detailed examination of alloy microstructures and cyclic load-induced dislocation structures.

Descriptors :   *Fatigue(Mechanics), *Crack propagation, *Nickel alloys, *Superalloys, *Powder metallurgy, Hot pressing, Isostatic pressing, Grain size, Grain structures(Metallurgy), Distribution, Temperature, Fatigue tests(Mechanics), Strain(Mechanics), Loads(Forces), Cyclic tests, Microstructure, Dislocations, Computer applications

Subject Categories : Properties of Metals and Alloys

Distribution Statement : APPROVED FOR PUBLIC RELEASE