Stainless Steel Round Bars
Giriraj Impex is a manufacturer, stockist, supplier and exporter of stainless steel round bars to ASTM A276 and A479 in grades 303, 304, 304L, 316, 316L, 321, 347, 410, 420, 431 and 17-4PH (ASTM A564). We manufacture stainless steel round bars in black (hot rolled or forged) and bright (peeled, turned, cold drawn or centreless ground) condition, as well as hexagonal and square bars, supplied in random lengths or cut to length.
Stainless bars are the starting point for shafts, valve stems, fasteners, pump parts, fittings and machined components that must resist corrosion, and for forged and machined flanges and rings.
Specifications
| Item | Details |
|---|---|
| Standards | ASTM A276 (general use), ASTM A479 (boilers and pressure vessels), ASTM A564 (17-4PH), ASTM A484 (general requirements) |
| Grades | 303, 304, 304L, 316, 316L, 316Ti, 321, 347, 310S, 410, 420, 431, 17-4PH; dual certified 304/304L and 316/316L |
| Shapes | Round, hexagonal and square bars |
| Condition | Black: hot rolled or forged, annealed. Bright: peeled, turned, cold drawn, centreless ground or polished |
| Tolerance (bright bars) | ISO 286 classes such as h9, h10 or h11 as ordered |
| Heat treatment | Solution annealed (austenitic); annealed, or hardened and tempered (martensitic); solution treated or aged (17-4PH) |
| Lengths | Random lengths or cut to length |
| Documents | Mill test certificate (MTC); ultrasonic testing and third-party inspection on request |
Choosing a stainless bar grade
| Grade | Family | Typical use |
|---|---|---|
| 304 / 304L | Austenitic | General machined parts, food and process equipment |
| 316 / 316L | Austenitic | Marine fittings, pump shafts and chemical service |
| 303 | Austenitic, free machining | Parts with heavy machining where corrosion is mild |
| 321 / 347 | Stabilised austenitic | Parts for elevated temperatures |
| 410 / 420 | Martensitic | Hardened valve trim, cutlery, wear parts |
| 431 | Martensitic | High-strength shafts, propeller shafts |
| 17-4PH | Precipitation hardening | High-strength shafts, valve parts, fasteners |
For seawater shafts and fasteners, duplex and super duplex bars are also used.
Mechanical properties
ASTM A479 sets minimum mechanical properties for annealed austenitic bars, shown below. The mill test certificate gives the composition and properties of each heat.
| Grade | Tensile strength, MPa (ksi) | Yield strength, MPa (ksi) | Elongation in 50 mm, % | Reduction of area, % |
|---|---|---|---|---|
| 304 | 515 (75) | 205 (30) | 30 | 40 |
| 304L | 485 (70) | 170 (25) | 30 | 40 |
| 316 | 515 (75) | 205 (30) | 30 | 40 |
| 316L | 485 (70) | 170 (25) | 30 | 40 |
Chemical composition as given in ASTM A479 / A276 for each grade.
Black bars and bright bars
Black bars keep their hot-rolled or forged surface and are used where the part will be machined all over, or for forging stock. Bright bars have the outer layer removed and are finished to a close diameter tolerance with a clean, smooth surface, so they can be used for shafts and pins with little or no further machining. Peeled and turned bars remove surface defects from the hot-rolled skin; cold-drawn bars gain a little strength from cold work; centreless-ground and polished bars give the closest tolerance and finest finish. Large diameters are produced by forging and are supplied rough turned.
Manufacturing and quality checks
Bars are hot rolled or forged from billets of the specified grade, heat treated, straightened and finished to size, then cut and marked with grade, size and heat number. Each lot is checked for diameter, straightness and surface. Ultrasonic testing for internal soundness, intergranular corrosion testing and third-party inspection can be added, and bars can be supplied to NACE MR0175 / ISO 15156 on request.
Ordering stainless bars
Please give the grade and standard, shape and size, tolerance, condition (black or bright, heat treatment), length, quantity and any tests or inspection required.
Hexagonal and square bars
Stainless hexagonal bars are machined into nuts, unions, plugs and fitting bodies, where using the hexagon saves a milling operation; square bars are used for keys, valve spindles and forged parts. Both are supplied cold drawn or hot rolled in the same grades as round bars. Bright hexagons are measured across flats and supplied to a close tolerance suitable for spanners and sockets, so please give the across-flats size and tolerance when ordering.
Applications and related products
Stainless round bars are used for pump and valve shafts and stems, stainless steel fasteners, forged and machined pipe fittings and flanges, marine hardware, food and pharmaceutical machinery, and general engineering. Thin sections are supplied as stainless steel wires. Our stainless range also includes seamless pipes, welded pipes, tubes, plates, sheets, coils, circles, rings, angles, channels and flats. All bar materials are on the round bars, rods and wires page, and grade details on the stainless steel page.
Frequently Asked Questions
ASTM A276 covers stainless steel bars and shapes for general use, and ASTM A479 covers bars for boilers and other pressure vessels. Precipitation-hardening grades such as 17-4PH are supplied to ASTM A564.
A bright bar has had its hot-rolled surface removed by peeling, turning, cold drawing or grinding, giving a clean surface and a close diameter tolerance, such as ISO h9 or h11.
303 is a free-machining austenitic grade with added sulphur, so it machines much more easily than 304. Its corrosion resistance and weldability are lower, so it is used for parts where machining matters most.
Austenitic grades such as 304 and 316 cannot be hardened by heat treatment, only by cold work. Martensitic grades such as 410, 420 and 431, and precipitation-hardening 17-4PH, can be heat treated to high strength.
Yes. Bars are supplied in random lengths or cut to the lengths stated on the order. Please give the length tolerance if it matters for your machining.
Yes. Bars meeting the low carbon limit of 316L and the strength of 316 can be certified to both grades under ASTM A276 and A479.
Request a Quote for Stainless Steel Round Bars
Tell us the product, grade, size, standard, quantity and delivery location, and our sales team will reply with a quotation.