Elastic and Fatigue Properties of Vacuum Remelted Versus Air-Melted Ni-SPAN-C Alloy 902 for Bourdon Tubes

Abstract

Under sponsorship of the ASME Subcommittee on Low Pressure Measurement, four companies participated in processing and evaluating vacuum-remelted versus air-melted NI-SPAN-C Alloy 902 (Iron-Nickel-Chromium-Titanium) Bourdon Tubes. The results substantiate the opinion that the cleaner material produced by vacuum remelting will result in a reduction in the number of stress risers, which in turn will improve the fatigue life of the material and reduce the spread in the number of pressure cycles at failure. The vacuum-remelted alloy did not display any significant improvement with respect to other physical properties, such as hysteresis.—Experimental results and data are reported, including the test methods employed for pressure cycling the Bourdon Elements to determine fatigue life.