What Is the ASTM A484 Specification?
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Scope of ASTM A484
ASTM A484/A484M sets the general requirements for wrought stainless steel bars, billets, shapes, and forgings, excluding wire. It is invoked by product specifications that cover the specific grade, including A276 (bars and shapes), A314 (billets and bars for forging), A479/A479M (bars for boilers and pressure vessels), A564/A564M (precipitation-hardening bars), and A582/A582M (free-machining bars). When a purchase order cites A484, the supplier must meet the general requirements of A484 plus the grade-specific requirements of the product standard.
Product Forms and Material Conditions
Products under A484 may be supplied in several conditions, which must be stated on the order: hot-worked; hot-worked and annealed; hot-worked, annealed, and cold-worked; or hot-worked, annealed, and heat-treated. Austenitic and austenitic-ferritic (duplex) grades must be solution annealed with proper quenching and rapid cooling. Martensitic and precipitation-hardening grades are furnished in the annealed or heat-treated condition specified by the product standard.
Dimensional Tolerances
| Product and condition | Typical tolerance basis |
|---|---|
| Hot-finished rounds, turned, and square bars | Diameter or distance-across-flats per A484 Table 1; turned bars normally available 50-625 mm diameter |
| Hot-finished hexagonal and octagonal bars | Distance across flats per A484 Table 2 |
| Hot-finished flat bars rolled as bars | Thickness and width per A484 Table 3 |
| Flat bars cut from strip or plate | Width and thickness per A484 Table 4 |
| Cold-finished round bars | Diameter per A484 Table 5, with tighter limits for precision ground stock |
| Cold-finished hex, octagon, and square bars | Distance across flats per A484 Table 6 |
| Straightness | Machine-straightened hot- or cold-finished bars per A484 Table 8, commonly 1/16 in per 4 ft for cold-finished rounds |
Out-of-round is measured as the difference between maximum and minimum diameter at the same cross-section; out-of-square is the difference between the two opposite-face dimensions of a square bar. Tolerances tighten with cold finishing, and precision-ground bar follows even tighter diameter limits.
Ordering Information and Certification
A484 is written in both inch-pound and SI units; the order must state which system applies, or the inch-pound system governs by default. A complete order specifies the product standard and grade, condition, dimensions and tolerances, finish, quantity, testing, and the certification required. Material is tested for chemical composition and mechanical properties per the product standard, and typical documentation includes the mill certificate with heat number, test results, and heat treatment records.
A484 and Related Bar Standards
A276: hot-finished or cold-finished stainless bars and shapes, the most common companion standard.
A479: stainless bars for boilers and pressure vessels, with tighter requirements.
A564: precipitation-hardening stainless bars such as 17-4PH and 15-5PH.
A582: free-machining stainless bars (added sulfur or selenium).
A314: stainless billets and bars for forging.
Common Misconceptions
'A484 is a grade standard.' No, it is a general requirements standard; the grade and product form come from A276, A479, A564, or another companion specification.
'All A484 bars are annealed.' Condition depends on the order; hot-worked, annealed, cold-worked, and heat-treated conditions are all permitted.
'Tolerances are the same for hot- and cold-finished bar.' Cold-finished bars have tighter diameter and straightness tolerances than hot-finished bars.
Frequently Asked Questions
What is the ASTM A484 specification?
It is the general requirements standard for wrought stainless steel bars, billets, shapes, and forgings, covering tolerances, conditions, heat treatment, and testing for products ordered under companion standards such as A276.
What standards reference A484?
A276, A314, A479, A564, A565, A582, A638, A705, and related bar and forging specifications reference A484 for general requirements.
What is the difference between A484 and A276?
A276 specifies the stainless grade, chemistry, and mechanical properties for bars and shapes; A484 provides the general requirements such as tolerances, finish, and inspection that apply to those bars.
Does A484 cover stainless wire?
No. Wire is explicitly excluded from A484; it is covered by A555 general requirements and product standards such as A313 for spring wire.
What straightness tolerance does A484 allow?
Machine-straightened hot- or cold-finished bars commonly allow 1/16 inch in any 4-foot length, with full-length variation scaled to total length; cold-finished rounds are the straightest product.
Are A484 tolerances in inches or millimeters?
Both. A484/A484M is dual-unit; the order must state whether inch-pound or SI units govern the acceptance.
