SEDL / STP / STP579-EB / STP29168S

Cryogenic Toughness Through Microstructure Control in an Iron-Nickel-Titanium Alloy

Jin, S
Assistant research engineer, graduate student, associate professor and professor, University of California, Berkeley, Calif.

Whitaker, B
Assistant research engineer, graduate student, associate professor and professor, University of California, Berkeley, Calif.

Morris, JW
Assistant research engineer, graduate student, associate professor and professor, University of California, Berkeley, Calif.

Zackay, VF
Assistant research engineer, graduate student, associate professor and professor, University of California, Berkeley, Calif.

Pages: 13    Published: Jan 1975

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Abstract

This paper discusses the selection of composition and processing of an iron-nickel-titanium (Fe-Ni-Ti) alloy having a favorable combination of strength and toughness at cryogenic temperatures. Criteria on alloy composition lead to the choice of low interstitial Fe-12Ni-0.25Ti. The alloy has a naturally favorable microstructure, but cryogenic toughness must be imparted through grain refinement. Several alternate procedures are identified; four of these are discussed in detail, along with the resulting tensile properties at 77 K, Charpy impact energies at 77 and 5 K, and behavior in fracture toughness tests at 77 K. Alloys are obtained having yield strengths to 150 ksi with excellent impact toughness to 5K.