Grain Refinement through Thermal Cycling in an Fe-Ni-Ti Cryogenic Alloy.
CALIFORNIA UNIV BERKELEY DEPT OF MATERIALS SCIENCE AND ENGINEERING
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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
- Properties of Metals and Alloys