QQ-S-741 was the U.S. federal procurement specification for carbon steel structural shapes, plates, and bars. Its final revision, QQ-S-741D, was issued on December 2, 1968, and canceled on March 13, 1987. The Department of Defense named ASTM A36/A36M as the replacement standard.1Defense Logistics Agency. QQ-S-741D – Cancellation If you are reading a legacy drawing or an older government contract that calls out QQ-S-741, A36 is almost always the current equivalent, though the substitution still needs to be verified grade by grade.
What QQ-S-741 Covered
The specification applied to carbon steel of structural quality in three product forms: hot-rolled shapes (wide-flange beams, channels, angles), plates, and bars.2EverySpec. QQ-S-741D, Federal Specification: Steel, Carbon: Structural Shapes, Plates, and Bars Materials were organized into types and grades tied to specific chemical compositions and mechanical properties. Each grade set limits on elements such as carbon and manganese and required minimum values for tensile strength and yield point, letting procurement officers match the steel to a project’s demands.
ASTM A36 as the Replacement
ASTM A36/A36M covers carbon structural steel in the same product forms QQ-S-741 addressed: shapes, plates, and bars. Its headline mechanical properties are a minimum yield strength of 36,000 psi (250 MPa) and an ultimate tensile strength range of 58,000 to 80,000 psi (400 to 550 MPa). Those values make A36 the workhorse grade for general structural use in buildings, bridges, and similar construction, and in most cases A36 meets or exceeds what QQ-S-741D required for general structural service.
When cross-referencing an old callout to A36, the values to compare are yield strength, tensile strength, elongation, and chemical composition limits.
Substituting on a Legacy Project
QQ-S-741 shows up most often on maintenance, repair, or renovation work at older government facilities, where structural drawings from the 1960s through the mid-1980s may reference the specification directly. The task is to identify a current ASTM grade whose mechanical and chemical properties match or exceed what the original grade required.
For most straightforward structural work, A36 is the answer, because the DoD cancellation notice names it as the replacement. Documentation is the pivot. On a government contract, the contractor supplying the replacement steel generally needs to provide mill test reports showing the material meets the mechanical properties the original design assumed. If the drawings call out a specific QQ-S-741 grade whose properties differ from A36’s baseline, the engineer of record should verify compatibility before approving the substitution.
This matters most on load-bearing repairs where the original designer picked a particular grade for a reason. A steel with a lower yield strength than the original can compromise structural capacity. Going the other direction is not automatically safe either: higher-strength grades can behave differently during welding and may require different preheat and interpass temperature controls.
Where to Find the Original Document
The Defense Logistics Agency’s ASSIST database catalogs both active and canceled military and federal specifications, and its public QuickSearch tool will pull up QQ-S-741D along with its cancellation status.3Defense Logistics Agency. FAQs – Canceled Documents The cancellation notice itself is a short document naming ASTM A36/A36M as the approved replacement.1Defense Logistics Agency. QQ-S-741D – Cancellation
The notice alone will not tell you whether a specific old grade maps cleanly onto A36. For a proper grade-by-grade comparison you need the full original text of QQ-S-741D, which document archives such as EverySpec make available alongside the cancellation notice.4EverySpec. Federal Specification QQ-S-741D – Steel, Carbon: Structural Shapes, Plates, and Bars With the original in hand, the chemistry and mechanical tables can be checked line for line against the modern ASTM standard before any material is ordered.