Comparative Fracture Toughness Testing of Cryogenic Alloys at Liquid Helium Temperature.

摘要

Fracture behavior of the Fe-12Ni-0.25Ti alloy grain refined through thermal cycling was studied down to liquid helium temperature using a simple method of cryogenic fracture toughness testing. Comparison tests were also made with two other common cryogenic alloys. Ultrafine grained Fe-12Ni-0.25Ti alloy,which is 100% ferritic,behaved in a ductile manner similar to 304austenitic steel. It was shown that the ductile-brittle transition temperature of the ferritic steel specimen can be suppressed below liquid helium temperature by grain refinement even in the presence of a sharp crack. Yield strength at liquid nitrogen temperature,and yield strength at liquid helium temperature were obtained. (Modified author abstract)