Effect of Cold Reduction and Thermal Treatment on Tensile Properties of a Nickel - 2 Percent Beryllium Alloy at Cryogenic Temperatures

This investigation was conducted to determine the tensile properties of a precipitation-hardenable nickel -2 percent beryllium alloy Berylco 440 in 0.020-inch-thick sheet form at temperatures from ambient to -423 degrees F. The properties of this alloy over the range of commercially available conditions were determined, and the effects of extended aging times and temperatures as well as degrees of cold reduction greater than those commercially available were studied. Specimens parallel to the direction of rolling were tested at ambient temperature, -320 degrees F, and -423 degrees F. No transverse properties were determined. The alloy studied has high toughness and elongation at cryogenic temperatures in comparison with other high-strength materials. When cold-reduced 60 percent and aged, yield and notch strengths at -423 degrees F were 267 and 219 ksi, respectively, and average elongation was 19 percent. Overaging appeared to be of no benefit since it reduced the -423 degrees F ultimate and yield strengths without increasing the notch strength. Comparison of the limited data obtained in this investigation and elevated-temperature data from the alloy supplier indicate that this alloy would be usable at temperatures ranging from -423 degrees to about 800 degrees F.