ГОСТ standards for long products: round bar, hexagon, angle
Stainless long products are governed by a separate group of standards, and the main one for round bar is ГОСТ 2590: it defines the product range of hot-rolled round products. Working alongside it is ГОСТ 2591, which describes the requirements for the rolled product itself.
The wording "stainless round bar ГОСТ" without stating the standard and the accuracy class does not give the supplier a sufficient brief, and what ends up in the trade is whatever happened to be in the warehouse.
Below: how the standards for round bar are structured, how calibrated product differs from hot-rolled, what matters for angle and hexagon, and who checks quality at acceptance.
ГОСТ 2590 and 2591
The two documents work as a pair. One describes which sizes exist, the other describes what requirements the rolled product must meet.
ГОСТ 2590 is the product range of hot-rolled round products. It states which diameters are produced and to what accuracy. Accuracy is either normal or increased, and this affects how the round bar sits in the chuck and how much metal is lost to turning.
ГОСТ 2591 covers the technical requirements for the rolled product: diameter tolerances, ovality, straightness, length, surface requirements and marking. This is where it is set out what counts as a conforming bar and what does not.
| Parameter | What is regulated | What it affects |
|---|---|---|
| Diameter | nominal size and limit deviations | chuck fit, turning |
| Ovality | difference in diameter across the section | accuracy of turning |
| Straightness | deviation of the axis from a straight line | feeding into an automatic lathe, cutting |
| Length | fixed, random, multiple | consumption when cutting to size |
| Surface | scabs, laps, cracks, decarburisation | strength and appearance of the part |
| Marking | linking the bar to a batch | acceptance and claims |
Stainless round bar to ГОСТ is always a combination of two documents plus the standard for the steel grade. The grade (for example, 12Х18Н10Т or AISI 304) comes from the grade standard, while the product range and requirements come from the standards for the rolled product.
The practical conclusion: state the diameter, accuracy, length and grade in your order. If accuracy is not specified, the standard allows normal accuracy — and that will not be enough for every job.
Calibrated product
Calibrated round bar is product that, after hot rolling, has undergone additional processing: drawing, turning or grinding. As a result it is more accurate and cleaner than hot-rolled bar.
| Feature | Hot-rolled | Calibrated |
|---|---|---|
| Diameter accuracy | normal or increased | high |
| Surface | scabs and laps possible | clean, free of rolling defects |
| Straightness | regulated | less |
| Application | structures, machining, forgings | automatic lathe machining, fasteners, precision parts |
| Length | 6 m, random | fixed, for automatic lathes |
Calibrated product is chosen where the part goes onto an automatic lathe and it matters that the bar feeds consistently and holds size on the first pass. If you are going to rough-turn the bar anyway, there is no need to pay extra for calibration.
A separate note on ground round bar. Grinding removes surface defects and delivers an accurate size. It is the next step after calibration and is used for parts with high surface requirements — shafts, axles, food equipment parts.
Grades for calibration. Austenitic grades are usually calibrated — AISI 304, 316L and also 201. The higher the strength of the grade, the harder it is to draw it cold, so for some grades calibrated product is less common than hot-rolled. On the GCX exchange, calibrated round bar is available in diameters of 10–30 mm and hot-rolled bar in 40 and 60 mm.
Angle and hexagon
Angle. Stainless angle to ГОСТ is governed by the standards for long products, which set the leg width, thickness and tolerances. The order states three numbers: leg width × leg width × thickness. The exchange offers AISI 304 angles 40×40×4 and 50×50×5 mm, length 6000 mm, hot-rolled.
What is checked on an angle:
- perpendicularity of the legs — it determines whether the angle will fit into the structure without adjustment;
- leg thickness — this is what carries the load;
- straightness — over the length of a six-metre bar it accumulates noticeably;
- internal corner radius — important for butt welding.
Hexagon. ГОСТ hexagon 12Х18Н10Т is governed by the standard for long products, where the main dimension is the diameter of the inscribed circle, that is, the "across-flats" size. Hexagon goes into nuts, bushings, milled parts, handles and elements that need to be turned with a wrench. Finished fasteners are covered by their own product standards, including DIN 11850 for imported nuts made of AISI 304.
A practical point: hexagon is likewise divided into hot-rolled and calibrated, and the latter is chosen for automatic lathe machining.
Who checks quality
Quality is checked by the consumer at acceptance, while the manufacturer guarantees it through the certificate. A third party appears if the contract provides for one.
The acceptance procedure:
- Check the marking against the certificate. The batch and heat number on the tag must match the certificate.
- Measure the diameter or across-flats size at several cross-sections and along the length — this reveals ovality and taper.
- Check the straightness. Lay the bar on a flat surface and assess the gap along its length.
- Inspect the surface. Scabs, laps, cracks and traces of rough grinding are all grounds for a claim.
- Check the length and quantity. The fixed length and the number of bars in the bundle must match the delivery note.
A common mistake is accepting long products on the basis of grade without checking the geometry. A bar of genuine grade with out-of-tolerance ovality will not become conforming just because the composition is right. The second mistake is not stating the accuracy class in the order: then a complaint about deviations comes up against the wording of the standard.
What to remember about the grade. AISI 304 is close in composition to 08Х18Н10, and 12Х18Н10Т is close to AISI 321. But when buying long products, what matters more than the similarity of grades is an exact match with what is specified in the design documentation. The full equivalence table is in the grade guide.
Frequently asked questions
What does ГОСТ 2590 regulate?
The product range of hot-rolled round products: which diameters are produced and to what accuracy. The technical requirements for the rolled product — tolerances, ovality, straightness, surface — are set by the companion document.
How does calibrated round bar differ from hot-rolled?
In accuracy and surface. Calibrated bar is drawn or turned, so it delivers a stable size and a clean surface. Hot-rolled bar is cheaper, but its tolerances are wider and rolling defects are possible.
Is there a ГОСТ for 12Х18Н10Т hexagon?
Yes, long products are governed by the standards for the relevant profile, where the main dimension is the across-flats size. In addition, state the steel grade, accuracy and length. Finished nuts and studs are covered by product standards.
Which ГОСТ applies to stainless angle?
Angle is governed by the long-product standards, which set the leg width, thickness and tolerances. The order states the profile, grade, length and accuracy. The exchange offers 40×40×4 and 50×50×5 mm angles made of AISI 304.
What is checked at acceptance of round bar?
Diameter and ovality at several cross-sections, straightness, length, surface and marking. The certificate is checked separately: grade, batch number and accuracy. Anything outside tolerances is recorded before the acceptance is signed.
What grades does stainless round bar come in?
The common product range includes AISI 304, 316L and 201, as well as 12Х18Н10Т. The grade is chosen by the environment: 304 for water and food media, 316L for chlorides and chemicals, 201 for interiors and furniture.
Can hot-rolled round bar be replaced with calibrated bar?
Yes, if the dimensions and grade match. Calibrated bar is more accurate, so it will suit anywhere hot-rolled is needed, but it will cost more. The reverse substitution is not always possible: hot-rolled bar is not suitable for automatic lathe machining.
Place an order for long products
The GCX exchange trades AISI 201, 304 and 316L round bar in diameters of 10–60 mm and 40×40×4 and 50×50×5 mm angle made of AISI 304. An order fixes the grade, size, surface and shipment week.