AMS 6488 is a sub-type specification of Tool Steel H11 that is part of the “H” group of steels. AMS 6488 has high chromium and low carbon content and is characterized by high impact toughness. Thanks to this quality, AMS 6488 finds use in the aerospace industry for manufacturing of landing gear for aircrafts and rotor blades for helicopters. AMS 6488 may look promising for use in hot-work applications, such as die and tool making, but it doesn’t find a lot of use there. It is available as bar and forging.
Depending on the heat treatment used on the parts, AMS 6488 differs in toughness, hardness, yield strength, and ductility. The preferred heat treatment for achieving the best combination of these properties is by double tempering at 1020° F (550° C). The highest tempering should be done at 1200° F (650° C), while the lowest at 840° F (450° C).
AMS 6488 can be easily formed using conventional methods for machining and forging at 2050° F (1121° C), and it shows minimal distortion during deep-hardening and air-hardening thanks to the balanced alloy content. That said, machinability is 75-80 % relative to steels of the “W” group.