Accession Number : AD0775510

Title :   Grain Refinement through Thermal Cycling in an Fe-Ni-Ti Cryogenic Alloy.

Descriptive Note : Technical rept.,

Corporate Author : CALIFORNIA UNIV BERKELEY DEPT OF MATERIALS SCIENCE AND ENGINEERING

Personal Author(s) : Jin,S. ; Morris,J. W. , Jr. ; Zackay,V. F.

Report Date : JAN 1974

Pagination or Media Count : 40

Abstract : A thermal cycling technique which allows the grain refinement of Fe-12Ni-0.25Ti alloy in four cycles has been developed. The process consists of alternate annealing in gamma range and (alpha + gamma) range with intermediate air cooling. The transformation, microstructures and cryogenic mechanical properties on each cycling step are described. Due to the ultrafine grain size, the ductile-brittle transition temperature of this ferritic alloy in Charpy impact testing was suppressed below 6K. In fracture toughness testing at 77K, the mode of fracture was altered from brittle quasi-cleavage to complete ductile rupture through the grain refining. (Modified author abstract)

Descriptors :   *Iron alloys, *Nickel alloys, *Titanium alloys, *Grain size, Thermal cycling tests, Microstructure, Diffusion, Low temperature

Subject Categories : Properties of Metals and Alloys

Distribution Statement : APPROVED FOR PUBLIC RELEASE