303 Stainless Steel Tube – The World’s Most Machinable Stainless Tube for High-Volume CNC Production
When your CNC or Swiss-type lathe needs to run faster, 303 Stainless Steel Tube delivers the competitive edge. With 0.15–0.35 % sulfur deliberately added, this free-machining grade offers 2–3× higher machining speeds and superior chip-breaking compared to standard 304 or 316, while still providing good corrosion resistance for mild-service applications. From precision-machined valve stems and pump shafts to 303 se stainless steel tube for ultra-smooth surface finish, 303 stainless steel tube maximises spindle uptime, extends tool life, and reduces unit cost—making it the first choice for high-volume producers of turned, milled, or ground components worldwide.
Caption: 303Se Stainless Steel Tube – Selenium Grade for Ultimate Surface Finish & Chip Control on Swiss MachinesKey Features & Benefits
- Free-machining sulfur 0.15–0.35 % – 90 % machinability rating vs 45 % for 304
- Excellent chip break-up – longer tool life, lower production cost
- Good corrosion resistance for indoor, food-zone, and mild chemical environments
- Non-galling / non-seizing – ideal for moving screw-machine parts
- Non-magnetic in annealed condition; low permeability after cold work
- Available in round, square, and 303 se stainless steel tube configurations – full 303 stainless steel tubes range
- Full ASTM A582, A511, A484, EN 10297-2 compliance
- 100 % recyclable, RoHS compliant
Technical Specifications
Table 1 – Chemical Composition (ASTM A511)
| Element | 303 % | 303Se % | 304 % |
|---|---|---|---|
| Cr | 17.0–19.0 | 17.0–19.0 | 18.0–20.0 |
| Ni | 8.0–10.0 | 8.0–10.0 | 8.0–10.5 |
| S | 0.15–0.35 | ≤0.060 | ≤0.030 |
| Se | — | ≥0.15 | — |
| C | ≤0.15 | ≤0.15 | ≤0.08 |
| Fe | Balance | Balance | Balance |
Table 2 – Mechanical & Machinability Data
| Property | 303 Tube | 304 Tube | 316 Tube |
|---|---|---|---|
| Tensile Strength | ≥620 MPa | ≥515 MPa | ≥515 MPa |
| Yield Strength (0.2 %) | ≥310 MPa | ≥205 MPa | ≥205 MPa |
| Elongation in 2" | ≥35 % | ≥40 % | ≥40 % |
| Hardness HRB | 90–100 | ≤92 | ≤95 |
| Machinability Rating | 90 % (excellent) | 45 % (good) | 45 % (good) |
| Chip Break-Up | Superior | Fair | Fair |
| Weldability | Poor* | Excellent | Excellent |
*Welding not recommended due to hot-cracking risk; use 304/347 for welded joints and bolt on 303 parts.
Full Size Range Table
303 Stainless Steel Round Tube
| OD (mm) | WT (mm) | Length (m) | Finish | Standard |
|---|---|---|---|---|
| 3–25 | 0.5–3.0 | 6 or coil | Bright | ASTM A511 |
| 25–76 | 1.0–4.0 | 6 or coil | Bright | ASTM A511 |
| 76–150 | 2.0–12.0 | 6 or 12 | Pickled | ASTM A511 |
303 Stainless Steel Square Tubes
| Size (mm) | WT (mm) | Length (m) | Finish | Standard |
|---|---|---|---|---|
| 10×10 | 1.0–2.0 | 6 | Bright | ASTM A554 |
| 50×50 | 2.0–4.0 | 6 | Bright | ASTM A554 |
| 120×120 | 3.0–10.0 | 6 or 12 | Pickled | ASTM A554 |
303 Se Stainless Steel Tube Options
| Grade | Surface | Ra (µm) | Machinability | Application |
|---|---|---|---|---|
| 303 | Bright | ≤0.8 | 90 % | General high-speed |
| 303Se | Mirror | ≤0.4 | 95 % | Swiss-type lathes |
Custom oval, rectangular, and honed ID available.
Product Range & Market Info
As one of the world’s largest 303 stainless steel tube manufacturers and most reliable 303 stainless steel tube suppliers, we operate a 150 000 t/year free-machining mill with in-house centerless grinding and polishing lines dedicated to 303 stainless steel tubes production. Our 150 000 m² facility keeps 30 000 t of ready stock in Shanghai and Houston, ensuring immediate availability for global CNC shops and precision component producers. Whether you need one coil of 25 mm × 2 mm or a full vessel of 120×120 mm × 6 m, our mill-direct pricing and ISO-approved quality give you the competitive edge. Contact our export team today for the most updated quotation and downloadable 3.1 MTC.
Specialty products include complete 303 se stainless steel tube – selenium grade for ultra-smooth surface finish, manufactured under ASTM A582.
Caption: Complete Range: 303 Stainless Steel Round Tube & 303 Stainless Steel Square Tubes – Always in StockMain Applications
- Precision machined components – valve bodies, pump shafts, fasteners
- Pneumatic & hydraulic fittings – quick-connect nipples, adapters
- Instrumentation tubing – sensor housings, gauge lines
- Bushings, gears, electronic connectors – Swiss-type lathe parts
- Food-processing machined parts – mixer bases, hopper outlets
- 303 se stainless steel tube – ultra-smooth finish for medical devices
Caption: Mill-Direct from Top 303 Stainless Steel Tube Manufacturers – Ultra-Machinable 303 Stainless Steel Tubes Ready to ShipWhy Choose Us – Machining-Grade Specialist
- ISO 9001 & PED certified mill – EN 10204 3.1 & 3.2 MTC supplied
- 150 000 tons annual free-machining capacity – 5-day lead time
- In-house centerless grinding & polishing – Ra ≤0.4 μm mirror finish
- Same-day cutting & deburring – tolerances ±0.05 mm, chamfered ends
- Real-time stock portal – 24/7 visibility for any 303 stainless steel tube suppliers
- Global export – fumigation-free crates, vessel booking, insurance
Grade Comparison Table: 303 vs 303Se vs 304 vs 316 vs 416 vs 430F
| Grade/Type | S/Se % | Mo % | Machinability | Weldability | Magnetic | Relative Cost | Best Use |
|---|---|---|---|---|---|---|---|
| 303 | S 0.15–0.35 | 0 | 90 % | Poor | No* | 1.0× (base) | High-speed machining |
| 303Se | Se ≥0.15 | 0 | 95 % | Poor | No* | 1.1× | Ultra-smooth finish |
| 304 | ≤0.030 | 0 | 45 % | Excellent | No* | 0.95× | General corrosion |
| 316 | ≤0.030 | 2–3 | 45 % | Excellent | No* | 1.35× | Marine chloride |
| 416 | S ≥0.15 | 0 | 95 % | Poor | Yes | 0.9× | Magnetic fasteners |
| 430F | S ≥0.15 | 0 | 90 % | Poor | Yes | 0.8× | Non-corrosive shafts |
*Non-magnetic in annealed condition; slight magnetism possible after cold work.
FAQ – 303 Stainless Steel Tube
-
What is the machinability advantage?
303 stainless steel tube offers 90 % machinability vs 45 % for 304 – chip break-up is superior, tool life 2–3× longer. -
Can 303 stainless steel tube be welded?
Welding is not recommended due to hot-cracking risk; use 304/347 for welded joints and bolt on 303 parts. -
303Se vs 303?
303 se stainless steel tube contains ≥0.15 % selenium instead of sulfur, providing even better chip breaking and smoother surface finish. -
Square tube stock status?
303 stainless steel square tubes from 10×10 mm to 120×120 mm – 5 000 t ready inventory. -
Current pricing?
Mill-direct FOB China USD 2.40–2.80/kg depending on sulfur surcharge; fixed for 48 h. -
Minimum order quantity?
One bundle for stock sizes; full container (≈20 t) for mill-direct custom sizes. -
Lead time for mirror finish?
7 days for centerless grinding to Ra ≤0.4 μm; 24 h for standard 303 stainless steel tube. -
Do you export worldwide?
Yes, to 70+ countries including UK, Germany, India, UAE, South Korea, and Australia.
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Stop paying trader margins. Contact the largest 303 stainless steel tube manufacturers today for the latest price, immediate access to massive 303 stainless steel tubes stock, and same-day cutting of any 303 stainless steel round tube or 303 stainless steel square tubes.