A statistical study of the effects of processing upon the creep properties of GRCop-84

Copper-based alloys for structural high-heat-flux applications: a review of development, properties, and performance of Cu-rich Cu–Cr–Nb alloys

“…Ellis et al studied strain-rate dependence for annealed and 47% cold-worked GRCop-84 tensile specimens in a range of strain rates of 0.01-0.0008 s −1 . The annealed samples demonstrated limited dependence while the cold-worked samples had some dependence [86].…”

“…The simulated braze demonstrates how the alloys' properties will change after a braze (if required) or exposure to the highest realistic temperatures in the combustion chamber liner, and the same simulated braze was used for each brazed sample in de Groh et al's experiment. These results should be used more for comparison of high temperature exposure rather than property change after a braze cycle because the requirements for the individual alloys [40,94]. At the time of Decker et al's study, the most common production methods of GRCop-84 were as-extruded or asrolled following the extrusion, and these two forms were both creep tested [94].…”

“…The wall separating the cooling channel and hot side of the liner was observed gradually deforming without material loss over operating cycles and eventually rupturing when sufficient biaxial ductility was lost [19]. Wall thinning is a complex failure mode that has been the subject of debate and has been attributed to different forms of fatigue and creep with dominant mechanisms dependent on geometry, alloy choice, and liner environment [19,39,40]. Better understanding each of these contributions to wall thinning led to better designs throughout the SSME’s lifetime and into new rocket design.…”

“…Fabrication of GRCop-42 has been demonstrated with several techniques including hot extrusion and AM, any methods that work with GRCop-84 should be viable with GRCop-42. The specifications of extrusion, HIPing, and commercial rolling are detailed by Ellis et al [86].…”

“…GRCop-84’s thermal conductivity compared to similar high-heat-flux alloys is its weakest property due to its high alloying content and can be significantly impacted by impurities In 2000, Ellis and Keller with Thermophysical Properties Research Laboratory (TPRL), Inc. in West Lafayette, IN [93] calculated thermal conductivity and electrical resistivity of extruded GRCop-84 using the Kohlrausch method. Since both conductivity and resistivity are calculated, the Lorenz number could be determined and was measured between 29 and 480 K with 5 powder lots [93]. The Lorentz number was significantly higher than pure Cu’s and demonstrated a mild temperature dependence, but these results had not taken Fe impurity into account and are not accurate to current GRCop-84 chemistry.…”