Cold-formed structural tubing manufactured from precoated sheet steel — galvanized, 55% aluminum-zinc alloy, or zinc-5% aluminum alloy. Six grades classified by minimum yield strength, manufactured to ASTM A1076/A1076M-20.
A1076 is the spec to call out when you need certified structural-grade tubing with a verified galvanized coating already in place — agricultural framing, fence and signpost systems, solar racking, outdoor equipment frames, and any structural application that lives in the weather. Unlike A500 + post-galvanizing, A1076 starts with already-coated coil and runs it through the tube mill, so the inside and outside surfaces are both protected before the tube ever leaves the floor.
| Designation | Shape | Min Yield Strength | Min Tensile Strength |
|---|---|---|---|
| Round Grade 33 | Round | 33,000 PSI | 45,000 PSI |
| Round Grade 42 | Round | 42,000 PSI | 58,000 PSI |
| Round Grade 46 | Round | 46,000 PSI | 62,000 PSI |
| Shape Grade 39 | Square / Rect. | 39,000 PSI | 45,000 PSI |
| Shape Grade 46 | Square / Rect. | 46,000 PSI | 58,000 PSI |
| Shape Grade 50 | Square / Rect. | 50,000 PSI | 62,000 PSI |
Per ASTM A1076-20 Tables 2 (Round) and 3 (Shape). The grade number is the minimum yield strength in KSI. Round and shape have separate grade lists because cold-forming a square or rectangular tube work-hardens the corners more than rolling a round.
| Grade | Yield, min (PSI) | Tensile, min (PSI) | Elongation in 2″, min |
|---|---|---|---|
| Grade 33 | 33,000 | 45,000 | 25% |
| Grade 42 | 42,000 | 58,000 | 23% |
| Grade 46 | 46,000 | 62,000 | 21% |
Per ASTM A1076-20 Table 2. Elongation values apply to wall thicknesses ≥ 0.120″. For lighter walls, elongation is calculated per the formulas in the standard footnotes.
| Grade | Yield, min (PSI) | Tensile, min (PSI) | Elongation in 2″, min |
|---|---|---|---|
| Grade 39 | 39,000 | 45,000 | 25% |
| Grade 46 | 46,000 | 58,000 | 23% |
| Grade 50 | 50,000 | 62,000 | 21% |
Per ASTM A1076-20 Table 3.
| Coating | Reference Spec | Typical Use |
|---|---|---|
| Zinc (galvanized) | A653/A653M | General outdoor structural framing |
| 55% Aluminum-Zinc | A792/A792M | Higher-temperature / longer-life corrosion resistance |
| Zinc-5% Aluminum | A875/A875M | Improved formability with corrosion protection |
Per ASTM A1076-20 Section 7.1. The ordered wall thickness includes both base metal and coating (Section 6.1).
Per ASTM A1076-20 Section 4. Dimensional tolerances follow ASTM A500/A500M (Section 12.1.1) — see our A500 page for the full tolerance tables.
Mechanical tubing — Type 1 hot-rolled and Type 2 cold-rolled. Grades 1008–1020.
Cold-formed structural HSS. Grade B and Grade C. The bridge-and-building spec.
Galvanized mechanical tubing. Six Types covering precoated and post-galvanized.
ASTM A1076 is the standard specification for cold-formed welded structural tubing produced from metallic-precoated sheet steel. The coil is coated before it runs through the tube mill, so both inside and outside surfaces are protected — structural strength and corrosion resistance in one mill cert. Major Metals manufactures A1076 tubing to ASTM A1076-20.
Round Grades 33, 42, and 46, and Shape Grades 39, 46, and 50 — the grade number is the minimum yield strength in KSI. Rounds and shapes carry separate grade lists because cold-forming a square or rectangular tube work-hardens the corners more than rolling a round.
Zinc (galvanized), 55% aluminum-zinc alloy, and zinc-5% aluminum alloy coatings, applied to the sheet before tube forming per ASTM A1076-20 Section 7.1. The ordered wall thickness includes both base metal and coating.
When you want certified structural tubing with the coating already in place — no separate galvanizing step, both surfaces protected, and tighter dimensional consistency. Common calls: solar racking, agricultural framing, fence and signpost systems, and outdoor equipment frames.
Dimensional tolerances follow ASTM A500/A500M per A1076-20 Section 12.1.1 — the same OD, wall, straightness, and twist limits as structural HSS.
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