Report On Meeting To Review Maraging Steel Projects

Recent studies of the developments in welding steels with yield strengths greater than 150 ksi have included low-alloy martensitic steels, medium-alloy martensitic steels, nickel maraging steels, and bainitic steels. Only weldments from medium-alloy martensitic steels and nickel maraging steels have mechanical properties approaching those of the base plate without a complete postweld heat treatment. The most serious problem with the other steel is low toughness in the weld fusion zone. Adequate weld metal toughness under conditions of elastic strain can be obtarined over the entire 150 to 225 ksi yield-strength range only if the tungsten-arc welding process is used. Processes with higher deposition rates can produce comparable weld deposits only in the lower portion of the range. Above a yield strength of 200 ksi, 18Ni maraging steel weldments have the best combination of strength and toughness. Below 200 ksi, the HP 9-4-25 medium-alloy martensitic steel and 12Ni maraging steel weldments have nearly equal properties.

The memorandum summarizes the available information on the compatibility of liquid rocket propellants with prominent materials of construction. Fuels and oxidizers of current interest are discussed. The corrosion data which are presented will apply to storing, handling, and control equipment outside of missiles and to missile components excluding combustion chamber. The compatibility of materials with reaction products in combustion chambers, nozzles, etc., is not considered. Included in the summary are data for many nonmetallic materials. The memorandum is subdivided into sections according to the propellant. Each material of construction is rated for a given medium as belonging to one of four classes, based primarily upon corrosion resistance. Consideration also is given to such factors as catalytic decomposition and sensitivity to impact.