Accession Number : AD0718473

Title :   A New Refractory Economical-Composition Alloy for Prolonged Service at High Temperatures,

Corporate Author : FOREIGN TECHNOLOGY DIV WRIGHT-PATTERSON AFB OHIO

Personal Author(s) : Krylov,A. R. ; Kozlova,N. N. ; Gubanova,L. N. ; Ushakov,I. S. ; Smirnova,V. A.

Report Date : 19 NOV 1970

Pagination or Media Count : 11

Abstract : The work deals with the properties of the cast Kh25N25G6V5MBAR high-temperature alloy which was specially developed for prolonged service (up to 10,000 hr) at 900 degrees centigrade in atmospheres with a high content of hydrogen. In the cast state this alloy has an austenitic structure with a large number of carbides. Reheating at 900-1100 degrees centigrade for 1 hr with subsequent quenching resulted in the coagulation and partial dissolution of the carbides. The mechanical properties of specimens of melts containing 0.12 and 0.4 percent C were determined with the aid of short-term tensile tests and it was found that at room temperature the specimens with the higher C content displayed a markedly higher ultimate strength. At operating temperatures increasing the C content to 0.4 percent did not affect short-term strength but it significantly increased plasticity. In long-time (stress-rupture) strength tests increasing the C content produced no effect. The limits of the stress-rupture strength of this new alloy, which contains approximately 36 percent Fe, after 100, 1000 and 10,000 hr of exposure to 900 degrees C are 7.5-9.0, 5.0-6.0 and 3.3-4.0 kg/mm(superscript 2), respectively, i.e. they are nearly as high as in complex Cr-Ni alloys. Its impact strength in cast state is given.

Descriptors :   (*HEAT RESISTANT ALLOYS, METALLOGRAPHY), CHROMIUM ALLOYS, NICKEL ALLOYS, TUNGSTEN ALLOYS, MANGANESE ALLOYS, MOLYBDENUM ALLOYS, NIOBIUM ALLOYS, (U)NIOBIUM ALLOYS

Subject Categories : Metallurgy and Metallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE