AMS 6308 is a subtype specification of Steel Alloy 53, itself carburizing steel with high case hot hardness, high surface hardness, abrasion resistance, and excellent resistance to tempering. Due to these properties, AMS 6308 can be used in difficult conditions, such as higher temperature and low lubrication environments.
This alloy is also characterized by a flexible core, which makes it an excellent choice for components that transfer large impact loads, such as gears, drive shafts, and fasteners in the aerospace industry. AMS 6308 is available at Tech Steel & Materials as a bar and forging.
Heat treatments of AMS 6308 vary depending on what you want to achieve. That said, you should always start with carburizing, followed by annealing and oil quenching or air quenching in high-pressure nitrogen. One recommended heat treatment for achieving an outstanding surface hardness of 60 HRC and above is the following:
Carburizing is done at the temperature range of 1600 – 1700°F (870 – 930°C) in a vacuum furnace.
Slowly chill the part, followed by annealing for removing the internal stresses. Chill until the alloy reaches room temperature.
Oil quenching or high-pressure nitrogen quenching is then done at 1660 – 1700°F (905 – 920°C).
Sub-zero treatment at temperatures below -100°F (-75°C) ensures that the hardened layer exceeds the hardness of 60 HRC.
Tempering is done at 300 – 550°F (150 – 290°C) for the strength of approximately 1200 MPa and impact resistance in the region of 100 – 150 J.