Matweb has 71 listings for maraging steels. http://www.matweb.com/
[click 'Materials Type,' then under "Ferrous Metals,' scroll down to 'Maraging Steels' & click 'Find.']
Most are listed by AISI designation (generics).  Those listed by manufacturer are:
 
Vasco® 9-4-30 Specialty Steel, Heat Treatment: 899°C (1650°F) + Age
VascoMax® C-250 Specialty Steel, Heat Treatment: 927°C (1700°F) + Age
VascoMax® C-300 Specialty Steel, Heat Treatment: 927°C (1700°F) + Age
VascoMax® C-350 Specialty Steel, Heat Treatment: 927°C (1700°F) + Age
VascoMax® T-250 Specialty Steel, Heat Treatment: 816°C (1500°F) + Age
 
Special Metals UDIMET® Alloy 250 Maraging Steel
 
Timken Latrobe Marvac® 250 VIM-VAR; 10 in. High Strength Maraging Steel
Timken Latrobe Marvac® 250 VIM-VAR; 5 in. High Strength Maraging Steel
Timken Latrobe Marvac® 300 VIM-VAR; 10 in. High Strength Maraging Steel
Timken Latrobe Marvac® 300 VIM-VAR; 6.25 in. High Strength Maraging Steel
Timken Latrobe Marvac® 300 VIM-VAR; 5 RCS High Strength Maraging Steel

To continue with Ken's information,

Vasco & VascoMax are from Allegheny Technologies:

http://www.alleghenytechnologies.com/allvac/pages/Steel/default.htm

Special Metals' maraging steel is UDIMAR:

http://www.specialmetals.com/products/udimaralloy250.htm

And Timken's Marvac is here:

http://www.timken.com/products/specialtysteel/index.asp

Regards,

Cory

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