SAE 1144 steel

Grade, condition and product name

Niagara's named Stressproof brochure lists 100 ksi minimum yield and 115 ksi minimum tensile. Eaton's cold-drawn 1144 figures of 110–120 ksi yield and 120–130 ksi tensile are estimates. Keep the producer product and property basis with the value when specifying cold-drawn bar. Niagara Stressproof minimums, Eaton cold-drawn estimates

SAE 1144 is a medium-carbon, high-manganese, resulfurized steel used for machined bar components. Eaton's published grade chemistry is C 0.40–0.48%, Mn 1.35–1.65%, P ≤0.040% and S 0.24–0.33%. These are that supplier's chemistry entries; a purchase still needs its governing specification, analysis basis and edition. Eaton 1144 cold-drawn bar

Keep three identifiers separate: 1144 chemistry, the manufacturing/supply condition, and a producer's trademarked product. Niagara LaSalle's Stressproof® is produced through proprietary heavy-draft drawing and controlled stress relief. Nucor separately lists 1144SR NU-STANDARD™ stress relieved to ASTM A311 Class B. Neither name should be assigned automatically to unidentified or generic 1144 stock. Niagara Stressproof description; Nucor cold-finished products

Require Niagara’s named product explicitly if the approved drawing calls for Stressproof.

What ASTM A311 adds

ASTM's current listing is A311/A311M-04(2020), Cold-Drawn, Stress-Relieved Carbon Steel Bars Subject to Mechanical Property Requirements. Its public description distinguishes normal-draft Class A from heavy-draft Class B; the latter covers rounds and hexagons. The grade, class, condition and mechanical requirements belong together on the order. “A311” alone is incomplete. ASTM A311/A311M-04(2020)

Niagara's facts page describes additional Stressproof controls, including surface-defect inspection and warpage testing, and says mechanical testing is performed after processing. Those are named-product controls; their presence cannot be established from a generic chemistry certificate. Niagara Stressproof facts

For procurement, agree the required tensile properties, size/shape range, tolerances, surface acceptance, test frequency and inspection records. Identify what the certificate actually certifies and preserve traceability after cutting. A standard designation is not an individual bar's measured-property report.

Mechanical data with their qualifiers

The following references describe different bases and must not be combined into a single guaranteed property set:

Eaton also estimates 7–12% elongation in 2 in. and 240–270 BHN. Niagara makes elongation and reduction of area dependent on size and ASTM A311 Class B. Encore identifies its product as Class B and notes that it is not normally available above 4 in. diameter because of the cold work required. Eaton estimated properties; Niagara brochure; Encore 1144

Machining and dimensional stability

Encore links the sulfur content to machinability and describes stress relief as a way to minimize machining warpage. Niagara likewise makes controlled low stress and reduced distortion part of its named-product offering. Neither statement guarantees zero movement in an asymmetric finished component. Encore characteristics; Niagara product description

Plan the stock condition and machining sequence around the geometry. Removing substantial material, cutting keyways or making a slender shaft can make straightness and final inspection more important than an attractive catalogue strength. Establish the required machining allowance, support, intermediate checks and final dimensional acceptance. A supplied-bar straightness tolerance is not a promise that the finished shaft will remain within that tolerance after every operation.

A machinability percentage also requires its reference steel and test basis. It is not a cutting-speed instruction for a particular tool, machine, coolant or surface requirement. Develop settings for the actual operation rather than multiplying a generic number into an unrelated recipe.

Welding and surface hardening

Encore explicitly does not recommend welding its 1144 cold-drawn product. Treat welded fabrication or weld repair as a separate material/procedure decision; the grade's machining advantages do not establish weld suitability. Encore 1144 processing guidance

Niagara allows induction hardening of Stressproof but warns about quench cracks; its brochure calls for magnetic-particle inspection after heat treatment because the steel is resulfurized. That guidance is product-specific and must be read with the actual treatment route. Niagara Stressproof brochure

If a hard surface is required, specify case/depth and hardness requirements separately from core properties, distortion and crack acceptance. Subsequent heating should trigger review of the original cold-worked/stress-relieved property basis. Do not assume an as-supplied tensile certificate establishes final properties after a different thermal cycle. Define corrosion protection for the actual environment independently of the bar's strength or surface finish.

Bounded calculation example

Assume an ideal 1.000 in. diameter Stressproof round under uniform axial tension. Gross area is π/4 × 1² = 0.7854 in². Using the brochure's 100 ksi minimum yield entry gives a simple gross-section yield-force product of 78.54 kip. A 20 kip axial load gives 20 / 0.7854 = 25.46 ksi nominal stress. Niagara minimum-property basis

This is original illustrative arithmetic, not an allowable load or safety factor. It excludes holes, keyways, stress concentrations, bending, fatigue, connections, buckling and design factors. It also assumes the ordered and certified product actually meets the cited condition. Replacing the 100 ksi entry with a higher supplier estimate would not establish a higher guaranteed capacity.

Source versions and release record

ASTM lists A311/A311M-04(2020). The inspected one-page Niagara brochure and linked live supplier pages do not provide an explicit issue date used here; the brochure's 2024 upload directory is not treated as its edition. Retain producer/product identity, heat/lot, ordered specification and edition, class/condition, supplied dimensions, certifications and subsequent processing records with final inspection evidence.

See also grades, tempers and conditions.