MARAGING STEELSA family of low-carbon high-alloy steels typically containing 12 to 18% nickel, 3 to 5 molybdenum, 0 to 12 cobalt, 0.2 to 1.6 titanium, and 0.1 to 0.3 aluminum (one cobalt-free grade also contains 5 chromium) and noted for their high strength and toughness, simple heat treatment, dimensional stability during heat treating, good machinability, and excellent weldability. The term maraging refers to the martensitic structure that forms during heat treatment, which is a precipitation-hardening, or aging, treatment usually at 900°F (482°C). The 18% nickel kinds, the most well known, are produced in four grades to provide tensile yield strengths of 200,000 lb/in2 (1,379 MPa), 250,000 lb/in2 (1,724 MPa), 300,000 lb/in2 (2,069 MPa), or 350,000 lb/in2 (2,413 MPa). Although the 18% nickel steels were originally developed for aerospace applications primarily, they also are now used for die-casting dies, cold-forming dies, and molds for forming plastics.
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