303 Stainless Steel Rod Supplier
MTS supplies 303 stainless steel rod for high-volume turned parts. Round bar runs from 4 mm to 160 mm, cold drawn or ground, with hex and square bar for fittings.
303 to ASTM A582 and EN 10088-3 (1.4305)
Cold drawn to h9–h11; ground to h7/h8 with Ra 0.2–0.8 µm
303Cu for faster turning and light cold heading, Φ5–20 mm
Part of our 4,500 tons of stainless bar stock (out of 80,000 tons in total) in Wuxi
Why Machine Shops Buy 303 Stainless Round Bar From Us
01
Ground Bar for Precision Turning
Ground 303 bar from Φ5 to Φ30 mm holds h7/h8 with a Ra 0.2–0.8 µm finish. It feeds cleanly through guide bushings on sliding-headstock lathes.
02
A Full Free-Machining Range
303 round bar from Φ4 to Φ160 mm, 303Cu, and free-machining 316, 416, 420F and 430F. One supplier covers every free-cutting grade on your drawings.
03
Round, Hex and Square in One Grade
303 comes as round bar, hex bar from 8 to 41 mm and square bar from 10 to 60 mm. Nuts, fittings and adapters start from the right shape.
04
Lengths for Bar Feeders
Bars ship in 2, 3 or 6 m lengths with square-sawn ends. 3 m bars suit most bar feeders.
Shorter Cycle Times on Every Part
303 is 304 with added sulfur. The sulfur forms tiny manganese sulfide particles. They break chips short and reduce tool wear.
In practice, 303 machines much faster than 304. Tools last longer, and parts come off with a cleaner finish. For screws, fittings and bushings made by the thousand, that is the biggest cost saving you can make at the bar stage.
303 Stainless Steel Round Bar Range
303 Stainless Steel Round Bar
Cold drawn, h9–h11, Φ4–160 mm, for CNC turning. Also sold as 303 stainless round bar.
Precision Ground Stainless Steel Rod
Centerless ground to h7/h8, Ra 0.2–0.8 µm, Φ5–30 mm, in 303, 304 and 316L. Choose precision ground 303 stainless steel rod for Swiss-type lathes.
Ground and Polished Stainless Steel Rod
Ground, then polished, for pins, plungers and visible shafts.
303 Stainless Steel Hex Bar
Cold drawn hex bar for nuts, fittings and adapters, 8–41 mm across flats.
303Cu Round Bar
Copper-bearing 303 that turns faster and cold heads better than standard 303. Round bar Φ5–20 mm, ground bar Φ5–14.5 mm.
Specifications
| Item | Range |
|---|---|
| Grades | 303, 303Cu; precision ground also in 304 and 316L |
| Equivalents | UNS S30300; EN 1.4305; JIS SUS303; 303Cu ≈ EN 1.4570 |
| Round bar, cold drawn | 303: Φ4–160 mm; 303Cu: Φ5–20 mm; h9–h11 |
| Ground bar | 303: Φ5–30 mm; 303Cu: Φ5–14.5 mm; h7/h8; Ra 0.2–0.8 µm |
| Hex bar | 8–41 mm across flats |
| Square bar | 10–60 mm |
| Length | 2 m, 3 m, 6 m; 9 m and 12 m on request |
| Standards | ASTM A582, ASTM A276, EN 10088-3, JIS G4303 |
Is 303 the Right Rod for Your Parts?
303 is the easiest austenitic stainless to machine. That makes it popular, and also over-used. Here is how to decide whether it fits your part, and what to order when it does not.
What You Gain With 303
The sulfur in 303 breaks chips into short curls. On automatic lathes, this avoids bird-nesting and stoppages. You can run faster feeds and get longer tool life.
For a turned part with threads, cross holes and grooves, the saving per part is real. On a large run, it often outweighs any price difference in the bar.
What You Give Up
Corrosion resistance. The sulfide particles are weak points. In salt spray or chlorides, 303 pits earlier than 304. For outdoor or marine parts, use 304 or 316 instead.
Weldability. 303 tends to crack when welded. If the part will be welded, choose 304L.
Cold forming. Standard 303 does not cold head, bend or flare well. For lightly headed parts, 303Cu is the better choice. For heavy heading, use 304.
Polished appearance. Sulfide stringers can show as fine lines on a mirror finish. For decorative parts, 304 polishes better.
Our rule: use 303 for machined parts that stay indoors and are never welded. Use 304 for everything else.
303, 303Cu, Free-Machining 316 or a 400 Series Grade?
303Cu adds copper. It turns faster than 303 and tolerates light cold heading. It is popular for screws and small fittings.
Free-machining 316 is the free-machining choice when the part also needs molybdenum for chloride resistance.
416 is a free-machining martensitic grade. It is magnetic, hardenable and cheaper than 303. It suits parts that must be hard or magnetic, such as valve trim and motor shafts. Its corrosion resistance is lower than 303.
430F is a free-machining ferritic grade. It is magnetic but not hardenable, and is used for solenoid parts.
If you need hardness, look at our 410 Stainless Steel Round Bar range, which includes 416.
Precision Ground Bar for Swiss Lathes
Sliding-headstock lathes guide the bar through a bushing. That bushing needs a tight, round, smooth bar. Cold drawn bar is often not enough.
Precision ground stainless rod is centerless ground after drawing. It holds h7 or h8 and Ra 0.2–0.8 µm. Need another grade? Precision ground 304 stainless steel rod and precision ground 316 stainless steel rod follow the same process.
Ground bar costs more per kilogram. But it cuts scrap and machine stops. If you run Swiss-type machines, it nearly always pays.
How to Order 303 Round Bar
State the grade and standard, diameter and tolerance class. Add straightness, length and end condition. If chip control matters, ask for the actual sulfur value on the certificate.
For mixed sizes, list each diameter with its quantity. We pack and tag each size separately.
Frequently Asked Questions
Can 303 stainless steel rod be welded?
Not reliably. Its sulfur makes welds prone to hot cracking. Small tack welds may hold, but structural welds should use 304L. If your part needs both machining and welding, consider 304 with improved machinability.
Is 303 stainless rod food safe?
303 is used for some food machine parts, such as fittings and pins. It is not the first choice for surfaces in direct contact with acidic or salty food. Check the rule in your market before you specify it.
Is 303 rod magnetic?
Annealed 303 is essentially non-magnetic. Cold drawn small diameters may show slight magnetism. If you need very low permeability, tell us before ordering.
Is 303 the same as 303Cu?
No. 303Cu adds copper, so it turns faster and tolerates light cold heading. Standard 303 is the safer choice when your drawing names 303 to ASTM A582 or EN 1.4305.
Do you supply 303 stainless steel round bar suppliers and distributors?
Yes. We supply 303 drawn and ground bar to distributors that serve machine shops. You can mix diameters in one shipment from our Wuxi stock. Ask for our current 303 stock list.
What is ground stainless steel rod?
It is bar finished on a centerless grinder after drawing. Grinding gives tighter tolerance, better roundness and a smoother surface. It is used for shafts, pins and Swiss-lathe stock, not for electrical grounding.
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