I found this under "rocket science"!

Fairly recent developments (1960s and 1970s) are the maraging (age hardening) steels containing various percentages of steel
which develop extremely high strengths when aged at 850 to 950 F for a predetermined time. This aging results in formation of
a molecular structure within the steel which gives it good forming and forging characteristics; good stability during heat

But still no clue as to what "maraging" means
treatment; good retention of carbon, which imparts surface hardiness; and allows cooling at an uncontrolled rate in the normal
surrounding atmosphere without the need for specially constructed cooling facilities. Because of these properties, the maraging
steels are the most likely candidates for use in production of large (up to 260 inches diameter) motors for space booster and
Space Shuttle applications.