Stainless steel bar: round, flat, square and hexagonal
Stainless steel bar is the solid long product behind machined parts, fasteners, fittings, shafts and balustrade components, supplied round, flat, square and hexagonal. ULAMEX supplies bar in 304, 316L and duplex 2205, hot-rolled, cold-drawn and bright, to EN 10088-3, with a 3.1 certificate on request. This guide covers the forms, grades, conditions and finishes, standards and how the bar is used.
What stainless steel bar is
Stainless bar is a solid, straight-length product rolled or drawn from a stainless grade, used wherever a solid section is machined, formed or fixed rather than a hollow tube or a flat sheet. It is supplied hot-rolled for general and structural work and cold-finished (bright) where a smooth surface and tighter tolerance are needed for machining. The grade sets the corrosion resistance, exactly as for sheet and tube, and the form is chosen for the part: round for shafts and turned components, flat for supports and brackets, square and hexagonal for machined fittings and fasteners.
Bar forms
| Form | Typical use |
|---|---|
| Round bar | Shafts, pins, spacers, turned and machined parts, balustrade posts |
| Flat bar | Supports, brackets, base plates, frames and edging |
| Square bar | Machined parts, fittings, decorative and structural work |
| Hexagonal bar | Fasteners, nuts, machined fittings and valve parts |
Half-round bar is also available for handrail and edge details. Round bar is the most widely used, for anything turned or machined, while hexagonal bar is the starting stock for nuts and fasteners.
Grades for stainless bar
The grade is matched to the environment, as for all stainless. ULAMEX supplies bar in the common austenitic and duplex grades.
| Grade | Best for |
|---|---|
| 304 (1.4301) | General machined parts, structural and dry-environment bar |
| 316L (1.4404) | Marine, chemical, food and coastal parts |
| 316Ti (1.4571) | Elevated-temperature service |
| Duplex 2205 (1.4462) | High-strength and severe-chloride parts |
For the full grade detail see our guides to 304 and 316 stainless steel and duplex 2205: 304 for general work, 316L wherever chlorides or food contact are involved, and duplex 2205 where high strength and severe chloride resistance are both needed.
Conditions and finishes
Bar is supplied in several conditions, and the choice depends on the surface and tolerance the part needs.
| Condition | Character and use |
|---|---|
| Hot-rolled | General and structural bar, a scaled or pickled surface |
| Cold-drawn (bright) | Smooth bright surface and tighter tolerance for machining |
| Peeled / rough-turned | Larger round bar with a clean turned surface |
| Centreless ground | Precise diameter and fine surface for shafts and pins |
For precision machined parts and shafts, cold-drawn bright or ground bar gives the surface and tolerance needed; for general fabrication, hot-rolled bar is the economical choice.
Standards and tolerances
Stainless bar is supplied to EN 10088-3, which sets the grades, composition and mechanical properties. The dimensional tolerances follow a standard for each form.
| Standard | Scope |
|---|---|
| EN 10088-3 | Grades, composition and delivery conditions for bar and rod |
| EN 10060 | Tolerances for hot-rolled round bar |
| EN 10059 | Tolerances for hot-rolled square bar |
| EN 10061 | Tolerances for hot-rolled hexagonal bar |
| EN 10058 | Tolerances for hot-rolled flat bar |
| EN 10278 | Tolerances for bright (cold-finished) bar |
State the grade, form, dimensions, condition and any tolerance class with an enquiry, and add the 3.1 certificate requirement, so the delivered bar matches the part.
Sizes and how to specify
Round bar is specified by diameter, flat bar by width and thickness, square bar by side, and hexagonal bar by across-flats size, all supplied in standard mill lengths. Give the grade, form, dimensions and condition (hot-rolled, cold-drawn or ground) with an enquiry, and add the tolerance class and the 3.1 certificate requirement where the part needs them. Stating the condition matters as much as the size, because it sets the surface and the tolerance the machinist works to.
Applications
Stainless bar serves machining and fabrication across sectors. Machine shops turn round and bright bar into shafts, pins, spacers, bushes, fittings and valve components. Fastener makers use hexagonal and round bar for nuts, bolts and studs. Fabricators use flat and square bar for supports, brackets, frames and edging, and round bar for balustrade posts and handrail brackets. Food, chemical and marine work uses 316L and duplex bar for corrosion resistance, while general and structural work uses 304.
Machining stainless bar
Austenitic stainless work-hardens rapidly, so machining bar needs sharp tooling, positive feeds and a rigid set-up, and it machines more slowly than carbon steel. Cold-drawn bright and ground bar machine best because the surface and diameter are already close. Keep stainless bar and swarf away from carbon steel tooling to avoid iron contamination that later rusts, and, where the finished part is welded or machined heavily, passivate it to restore the passive layer. For food and marine parts, 316L is the usual machining grade.
Bar for stainless fasteners
Hexagonal and round bar is the starting stock for stainless nuts, bolts, studs and machined fasteners. The fastener corrosion class follows the bar grade: A2 fasteners are made from 304 (1.4301) for inland and general use, and A4 fasteners from 316 (1.4401 / 1.4404) for coastal, marine and chemical use, per ISO 3506. Choosing the fastener grade to match the structure, A2 inland and A4 at the coast, avoids the corrosion mismatch that lets a fixing fail before the part it holds. ISO 3506 also sets a strength property class marked after the grade: class 50 is soft and annealed for machined and formed fasteners, class 70 is cold-worked for standard strength, and class 80 is high-strength cold-worked. So an A4-70 bolt is a 316 fastener at standard strength, and A4-80 is the high-strength version, which matters where the bar is turned into a load-bearing fastener rather than a fitting.
Stainless bar versus other bar
Stainless bar is chosen where corrosion resistance or hygiene justify its cost over carbon or galvanised bar. Carbon steel bar is stronger and cheaper for general machining and structural work where corrosion is not a concern; galvanised bar suits outdoor structural use where a zinc coating handles corrosion. Stainless wins for food, marine, chemical and visible parts, and for fasteners and fittings that must not rust. ULAMEX supplies stainless alongside carbon steel bar, so a project sources the right material from one supplier.
Welding and finishing bar
Stainless bar welds readily with a matching low-carbon filler, 308L for 304 and 316L for 316, and drills and turns with standard workshop tooling. As with all stainless, keep bar and offcuts away from carbon steel tools and grinding media to avoid iron contamination that later rusts, and passivate a welded or heavily machined part to restore the passive layer. Austenitic grades work-harden, so drilling and turning use a firm feed and sharp tooling to avoid glazing the surface, and a welded joint is pickled or passivated to remove heat tint and rebuild corrosion resistance.
Stainless steel bar from ULAMEX
ULAMEX has supplied stainless steel since 1988, and bar is a core part of the range.
| What you get | Detail |
|---|---|
| Forms and grades | Round, flat, square and hexagonal bar in 304, 316L, 316Ti and duplex 2205 |
| Conditions | Hot-rolled, cold-drawn bright, peeled and ground |
| Standards | EN 10088-3, with EN 10060, 10059, 10061, 10058 and 10278 tolerances |
| Terms | 3.1 certificate on request, no minimum order on stocked SKUs, dispatch 2 to 7 working days |
Need stainless steel bar for a project? Send the grade, form, dimensions and condition, and ULAMEX will return a non-binding quotation. Browse the stainless steel bar and rod range, see our stainless steel sheet guide and supply capabilities, or contact the export desk at [email protected] or +48 504 424 761.
Frequently asked questions
What forms is stainless steel bar available in?
Round, flat, square and hexagonal, plus half-round for edge and handrail details. Round bar is the most widely used for turned and machined parts, and hexagonal bar is the stock for nuts and fasteners.
What is the difference between hot-rolled and cold-drawn bar?
Hot-rolled bar has a scaled or pickled surface and looser tolerance, and suits general and structural work. Cold-drawn (bright) bar has a smooth bright surface and a tighter tolerance, and is used for machined parts and shafts.
What grades is stainless bar available in?
304 (1.4301) for general work, 316L (1.4404) for marine, chemical and food parts, 316Ti (1.4571) for elevated temperature, and duplex 2205 (1.4462) for high-strength and severe-chloride parts.
What standard applies to stainless bar?
EN 10088-3 sets the grades, composition and delivery conditions, with dimensional tolerances to EN 10060 (round), EN 10059 (square), EN 10061 (hexagonal), EN 10058 (flat) and EN 10278 (bright bar).
What is bright bar?
Bright bar is cold-drawn or ground stainless bar with a smooth, bright surface and a tight tolerance, supplied to EN 10278. It is used where the part needs a good surface and close diameter, such as shafts and machined components.
Which stainless bar grade is best for marine use?
316L (1.4404) for coastal and marine parts thanks to its molybdenum content, and duplex 2205 (1.4462) where high strength is also needed.
Does stainless bar come with a material certificate?
Yes. A 3.1 inspection certificate to EN 10204 is supplied on request, giving the cast analysis and mechanical properties for full traceability, which matters for food, pressure and structural work.
Is stainless bar hard to machine?
Austenitic stainless work-hardens, so machining needs sharp tooling, positive feeds and a rigid set-up, and machines more slowly than carbon steel. Cold-drawn bright and ground bar machine best because the surface and diameter are already close.
What do A2, A4 and the property class mean on a stainless fastener?
A2 is a 304-type fastener for inland use and A4 is a 316-type fastener for coastal and marine use, per ISO 3506. The number after it is the strength class: 50 is soft and annealed, 70 is standard cold-worked, and 80 is high-strength cold-worked. So A4-70 is a standard-strength 316 bolt and A4-80 is the high-strength version.