AISI 9840 low alloy steel

[Flesh]

What is(was) AISI 9840 typically used for? Purpose for its creation? I see that it is a non-standard grade (USA), and is therefore not readily available here in the states. I am possibly looking to use it as a high-torque shafting material.

 

[metengr]

The only reference I could find regarding use of this material is ASTM A519, which is the Standard Specification for "Seamless Carbon and Alloy Steel Mechanical Tubing". AISI Type 9840 belongs in the family of Nickel-Chromium-Molybdenum low alloy steels. The combined additions of 1% Ni (which improves toughness) and 0.8% Cr with 0.25% Mo results in increased hardenability, in comparison to an AISI Type 1040 carbon steel.

If you are looking for a high torque application shaft material, I would recommend AISI Type 4340 alloy steel, which is in the same family of Ni-Cr-Mo alloys, and is probably easier to get.