304/304L Stainless Steel Round Bar
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304 stainless – the go-to grade for round bar
1.4301 (AISI 304), also designated X5CrNi18-10, is an austenitic chromium-nickel steel and the most widely used stainless grade of all. Roughly 18% chromium builds the passive oxide film on the surface, while about 9% nickel keeps the structure austenitic. 304 cannot be hardened by heat treatment – only by cold working – which is why cold-drawn bar is often harder than hot-rolled bar and may be slightly attracted to a magnet. Unlike the molybdenum-bearing grades, it contains no Mo: it handles the atmosphere, tap water and most food products well, but it is not intended for chloride-bearing environments.
What does 1.4301 / 1.4307 / 304 / 304L mean?
Some bars carry four designations in their name. This is multi-certified material: the heat chemistry falls within the limits of both 1.4301 and its low-carbon version 1.4307 (304L), so it meets the European and American specifications for both grades. That works in your favor, because the restricted carbon content improves the behavior of the steel in the weld zone. Bars listed simply as "1.4301 / 304" correspond to the standard grade. The actual chemistry of each heat is confirmed by an EN 10204 3.1 inspection certificate, issued on request.
Chemical composition and equivalents
| Grade | C | Cr | Ni | N |
|---|---|---|---|---|
| 1.4301 / 304 | ≤ 0.07 | 17.5–19.5 | 8.0–10.5 | ≤ 0.10 |
| 1.4307 / 304L | ≤ 0.030 | 17.5–19.5 | 8.0–10.5 | ≤ 0.10 |
Values in wt.% per EN 10088-1. Equivalent designations: 1.4301 = X5CrNi18-10 = AISI 304 = UNS S30400 · 1.4307 = X2CrNi18-9 = AISI 304L = UNS S30403.
Diameters from Ø 3 to Ø 350 mm, cutting and theoretical weight
This category lists more than 1,200 items: from slim Ø 3 mm bar for pins and precision shafts up to Ø 350 mm bar used to turn discs, rings and large machine shafts. Bars are sold in lengths such as 10 cm or 100 cm, and we cut to length on request. Each product page shows the theoretical weight, so you can easily convert the price of a piece into the price of 304 stainless per kilogram. As a guide, one meter of Ø 50 mm bar weighs about 15.6 kg (weight in kg/m ≈ 0.00623 × d², where d is the diameter in mm). Bars are typically produced to EN 10088-3 or ASTM A276 / A479 – the product standard is stated on the certificate. Permitted diameter deviations are listed on the round bar tolerances page, and why a bar with a seemingly matching diameter does not always fit into a tube is explained in our article Why a Ø14 mm bar won't fit into a Ø18×2 mm tube.
What is 304 round bar used for?
304 bar is the starting stock for turned and milled parts that must not rust but do not see aggressive media: shafts, pins, spacers, studs and bolts in non-standard lengths, handles, railing and furniture components. In food and packaging machinery it becomes rollers, guides and mixer blades, and in construction it is used for anchors and fasteners in indoor applications. The grade welds and polishes well. Being austenitic, however, it produces long, stringy chips and work-hardens quickly under the tool, so it needs sharp inserts, a constant feed and plenty of coolant.
304 or a different grade?
If the part will be exposed to seawater, road salt, pool water or chlorine-based cleaners, molybdenum-alloyed 316L / 1.4404 round bar is the better choice. For parts operating at elevated temperatures, titanium-stabilized 321 / 1.4541 stainless round bar is used, and where hardness after heat treatment is required – for knives or sliding shafts, for example – choose 1.4034 / 1.4057 / 1.4021 martensitic round bar. For heavy mechanical loads in chloride service, 1.4462 duplex round bar performs well, while furnaces and burners call for 1.4841 / 1.4845 heat-resistant round bar.
See also: the same grade in other product forms – 304 / 1.4301 seamless tube and 304 / 1.4301 stainless sheet. Free-machining 1.4305 / 303 bar with added sulfur – easier to machine, but less weldable – and all other grades are in the main stainless round bar category.