Stainless round bar: calibrated or hot-rolled
Calibrated round bar is chosen when an exact diameter and a clean surface matter: for automatic lathes, threads, bushes, shafts and axles. Hot-rolled — when a large diameter and strength are needed and the tolerance is wider: for turning, forgings, load-bearing parts.
The difference between them is in the production method, and that determines everything else.
In the GCX catalogue round bar is 10 positions: calibrated ⌀10–30 mm and hot-rolled ⌀40 and ⌀60 mm, length 6000 mm, grades 201, 304 and 316L.
Difference in production
Hot-rolled round bar is produced by rolling a heated billet between rolls. The diameter is large, the surface is dark, with scale, and the accuracy is lower. Such rolled product is suitable as a billet: a layer is removed on a lathe and the required size is obtained.
Calibrated round bar is made by cold deformation — drawing through dies, followed by straightening and, if necessary, annealing and pickling. The metal is not heated, so the surface stays bright and smooth and the diameter is held within a narrow range. Hence the second name: cold-drawn, or cold-deformed.
| Feature | Calibrated | Hot-rolled |
|---|---|---|
| Production | drawing, straightening, annealing | rolling of a heated billet |
| Surface | bright, smooth | dark, with scale |
| Diameters in the catalogue | ⌀10–30 | ⌀40, ⌀60 |
| Diameter accuracy | narrow range | wider |
| Typical operation | automatic lathe, thread, bush | turning, load-bearing part |
| HS code | 722220 | 722211 |
Another difference is work hardening. Cold drawing strengthens the surface layer, so calibrated round bar is stronger than hot-rolled of the same diameter, but less ductile and bends worse. If the part is later bent or welded, this is taken into account in advance.
Accuracy and tolerances
Accuracy is the main reason to pay for calibration. The bar goes into sliding-head automatic lathes, where the bar is fed from a guide bush: if the diameter varies, the part runs out and the tool wears faster. Calibrated product holds the diameter and ovality within a narrow range, so it suits such machines without additional peeling.
The tolerances are set by the standard. For long products these are ГОСТ 2590 and 2591: one describes hot-rolled round bar, the other calibrated bar and rolling accuracy. The exact deviation values are taken from the standard and the batch certificate, not from memory. The specification states the diameter, grade, delivery condition, standard and length.
Curvature and length are standardised separately. Calibrated round bar is supplied in straight bars, because a bent bar will not go into an automatic lathe. Hot-rolled bar may have noticeable curvature, and when machining a long part this affects the locating.
What to check at acceptance: the actual diameter with callipers or a micrometer, the ovality, straightness, the condition of the surface and the presence of a certificate. A magnet does not replace acceptance: austenitic 304 and 316L are weakly magnetic after annealing, and become noticeably more magnetic after drawing.
Where each is needed
Calibrated round bar means precision parts of small and medium diameter. Fasteners and studs, shafts and axles, bushes, nipples, parts for CNC machines and automatic lathes, guides, tie rods. Here not only the diameter is valued but also a clean surface: it reduces friction in the feed mechanisms and reduces tool wear.
Hot-rolled round bar means large diameters and load-bearing parts. Shafts of large cross-section, flanges, billets for turning and milling, valve parts, supports, forgings. If a machining allowance of 2–3 mm per side remains, the wide tolerance of hot-rolled product does not hinder.
By grade, the GCX catalogue offers round bar in 201, 304 and 316L: 201 is enough for dry rooms and inexpensive fasteners, 304 is taken for water and food environments (an analogue of 08Х18Н10), and 316L for chlorides, sea water and chemicals.
Catalogue calibrated diameters: stainless round bar 10 mm calibrated, stainless round bar 12 mm calibrated, stainless round bar 16 mm calibrated, stainless round bar 20 mm calibrated, stainless round bar 25 mm calibrated and stainless round bar 30 mm calibrated. Hot-rolled — ⌀40 and ⌀60. If you need to buy stainless bar for an automatic lathe, this range is enough: aisi 316 bar is represented in the catalogue by a diameter of ⌀20, aisi 304 bar — by six diameters, 201 stainless bar — by a diameter of ⌀12. The query 12х18н10т buy bar, 12х18н10т bar or buy stainless bar from analogue 321 means a grade with titanium: it is not in the catalogue, availability is checked by a separate order, and for most tasks 304 or 316L is suitable instead.
Price
The price of round bar depends on the grade, diameter, delivery condition, batch volume and logistics. Calibrated is more expensive than hot-rolled: drawing, straightening, annealing and inspection are added. 316L is more expensive than 304 because of nickel and molybdenum, 201 is cheaper owing to the partial replacement of nickel with manganese.
The price is also affected by nickel and molybdenum quotations: these are exchange-traded metals, and the alloying elements in the composition react to the market faster than the rolled product reaches the warehouse. Offers must be compared on the same basis: the same grade, diameter, delivery condition, tolerance and delivery terms. See current quotations on the prices page.
| Diameter | Weight of 1 m, kg | Metres per tonne | Form of delivery |
|---|---|---|---|
| ⌀10 | 0.62 | 1610 | calibrated |
| ⌀12 | 0.89 | 1120 | calibrated |
| ⌀16 | 1.59 | 630 | calibrated |
| ⌀20 | 2.48 | 403 | calibrated |
| ⌀25 | 3.88 | 258 | calibrated |
| ⌀30 | 5.58 | 179 | calibrated |
| ⌀40 | 9.93 | 101 | hot-rolled |
| ⌀60 | 22.34 | 45 | hot-rolled |
The weight of a metre of round bar is calculated by the formula 0.0062 × d², where d is the diameter in millimetres. The reverse conversion is also simple: metres per tonne = 1000 / weight of a metre.
Frequently asked questions
How does calibrated round bar differ from hot-rolled?
By the production method and the accuracy. Calibrated is drawn in the cold state: the diameter is within a narrow range, the surface is bright. Hot-rolled is rolled while heated: the diameter is larger, the surface is dark, the tolerance is wider.
What does calibrated bar mean?
It is a cold-drawn round bar, straightened and processed to an exact diameter. It can be fed into an automatic lathe without peeling, threaded, and used to obtain parts with a clean surface.
Which AISI 316 bar is available in the catalogue?
In the GCX catalogue 316L round bar is available calibrated with a diameter of ⌀20 mm, length 6000 mm. For other diameters and delivery conditions see the product range or place an order with the required parameters.
How to calculate the weight of stainless round bar?
The weight of a metre equals 0.0062 × diameter², where the diameter is in millimetres. For ⌀20 it is 2.48 kg per metre, for ⌀60 — 22.34 kg. The exact weight of a batch is taken from the certificate.
Can 12Х18Н10Т be replaced with 304 or 316L?
In many tasks yes: 304 is close in composition, 316L is more resistant in chlorides. But 12Х18Н10Т contains titanium and withstands heating and welding without heat treatment, so for heat-resistant and critical welded parts the replacement is agreed according to the operating conditions.
What is stainless round bar cut with?
A band saw, a cutting wheel, a laser or waterjet. For an exact length and a clean end face for an automatic lathe, a band saw or a laser is more often used; for thick hot-rolled bar, a cutting tool.
Choose round bar for the task
See the product range and state in the order the grade, diameter, delivery condition — calibrated or hot-rolled — and the shipment week.