MANUFACTURING PROCESS DEVELOPMENT FOR HIGH-STRENGTH STEELS
Final technical rept. 1 Jul 1963-30 Jun 1966
REPUBLIC STEEL CORP CANTON OH METALLURGICAL DEPT
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This document constitutes the Final Report on manufacturing process development of 18 percent nickel maraging steels and 9 percent nickel, 4 percent cobalt quench and temper steels. The effect of a number of processing and fabrication procedures on mechanical properties including toughness and stress corrosion was evaluated and is reported herein. None of the grades tested exhibited exceptional sensitivity to forging conditions but there was indication that the 18 percent nickel maraging steel possessed superior mechanical properties when reduced about 75 percent and finished at 1800-1850 F. Optimum results were obtained when the 9 percent nickel- 4 percent cobalt steel with 0. 45 percent carbon was reduced 75 percent but the 9 percent nickel -4 percent cobalt steel with 0.25 percent carbon exhibited better properties when reduced only 25 percent. The preferred finishing temperature for these steels was found to be 1900-1950 F. The results also suggest that in most cases vacuum-arc remelting results in some increase in fracture toughness. All of the steels proved to be rather insensitive to the rolling temperature but the greater reduction that the thinner plate underwent apparently resulted in improved toughness at least in the longitudinal direction. Weldability tests indicated that the 18 percent nickel maraging steel could be welded without severe degradation in heat-affected-zone mechanical properties provided the material was re-aged after welding. Welds of near 100 percent efficiency were produced in the 9 percent nickel-4 percent cobalt steels by quenching and tempering after welding.
- Metallurgy and Metallography
- Fabrication Metallurgy