Form: This specification covers a premium-quality@ low-alloy steel in the form of sheet@ strip@ and plate. Application: Primarily for heat treated parts which may be welded during fabrication@ which require through-hardening to high strength levels@ and which may be used at operational stress levels approaching the yield strength. Material may become notch sensitive when heat treated to a tensile strength level of 240@000 psi (1655 MPa) or higher; consequently caution should be exercised in this respect.