303 Stainless Steel Coil – The World’s Most Machinable Stainless Steel
When your CNC or automatic screw machine needs to run faster, 303 Stainless Steel Coil is the answer. With 0.15–0.35 % sulfur deliberately added, 303 delivers 2–3× faster machining speeds than 304 while still providing good corrosion resistance for mild atmospheres and food zones. The coil format feeds high-volume lines without interruption, reducing scrap and tooling costs. Whether you mass-produce precision screws, valve bodies, or instrument fittings, 303 Stainless Steel Coil maximises spindle uptime and profitability.
303 Stainless Steel Coil – Ultra-Machinable 2B Finish, Perfect for High-Volume CNC Production
Key Features & Benefits
- Free-machining sulfur 0.15–0.35 % – 2–3× faster production, longer tool life
- Excellent surface finish after turning, milling, or light polishing
- Non-galling / non-seizing – ideal for moving screw-machine parts
- Good corrosion resistance for indoor, mild chemical, and food-contact applications
- Non-magnetic in annealed condition; low permeability after cold work
- Available in thin gauges (0.3–6 mm) for light-duty cladding or precision stampings
- Full ASTM A895 / EN 1.4305 / AMS 5640 compliance
- 100 % recyclable, RoHS compliant
Technical Specifications
Table 1 – Chemical Composition (ASTM A895)
| Element | Min % | Max % |
|---|---|---|
| Cr | 17.0 | 19.0 |
| Ni | 8.0 | 10.0 |
| S | 0.15 | 0.35 |
| C | — | 0.15 |
| Mn | — | 2.00 |
| Si | — | 1.00 |
| P | — | 0.045 |
| Fe | Balance |
Table 2 – Mechanical & Physical Properties vs 304
| Property | 303 Coil | 304 Coil |
|---|---|---|
| Tensile Strength | 620 MPa (90 ksi) min. | 515 MPa (75 ksi) |
| Yield Strength (0.2 %) | 310 MPa (45 ksi) min. | 205 MPa (30 ksi) |
| Elongation in 2" | 35 % min. | 40 % |
| Hardness HRB | 90–100 | 92 max. |
| Density | 8.0 g/cm³ (0.289 lb/in³) | 8.0 g/cm³ |
| Machinability Rating | 90 % (excellent) | 45 % (good) |
| Magnetic Permeability | <1.02 (annealed) | <1.02 |
Standard Sizes & Finishes
| Thickness (mm) | Width (mm) | Coil ID (mm) | Finish Options |
|---|---|---|---|
| 0.30 – 0.50 | 1000 / 1219 / 1250 | 508 | 2B, BA |
| 0.60 – 1.00 | 1000 / 1219 / 1250 / 1500 | 508 | 2B, BA, No.4 |
| 1.20 – 3.00 | 1000 / 1219 / 1250 / 1500 | 508 / 610 | 2B, No.4, HL |
| 4.00 – 6.00 | 1219 / 1500 | 610 | No.1, HRAP |
| 8.00 – 12.0 | 1500 / 1524 | 610 | No.1, Pickled |
Custom slit widths from 20 mm; coil weight 2–25 tons.
Main Applications
- Automatic screw-machine parts: nuts, bolts, studs, washers
- Precision gears, shafts, bushings, couplings
- Valve and pump trim, pneumatic cylinders
- Instrument housings, sensor brackets, electronic connectors
- Aircraft fittings, seat-belt anchors, galley hardware
- Food-processing guides and rails (mild chloride environments)
- Decorative trim, elevator sills, architectural panels
2–3× Faster Machining – 303 Coil Enables Maximum Productivity on Automatic Screw Machines
Why Choose Our 303 Stainless Steel Coil
- ISO 9001 & PED certified mill – EN 10204 3.1/3.2 MTC supplied with every coil
- 100 000 ton annual capacity – 3–5 day lead time for standard sizes
- Precision slitting 6–1500 mm width, burr ≤0.03 mm, camber ≤1 mm/2 m
- Same-day shipment from 35 000 t stock – real-time coil portal
- Global export experience to 72 countries – fumigation-free crates, VCI film
- Factory-direct pricing – live surcharge update, fixed for 48 h after quotation
Massive Stock of 303 Stainless Steel Coil – Mill-Direct Supply, Same-Day Cutting & Delivery
Grade Comparison Table: 303 vs 304 vs 316 vs 303Se vs 416 vs 430F
| Grade | S Content | Mo % | Machinability Rating | Weldability | Magnetic | Relative Cost | Best Use |
|---|---|---|---|---|---|---|---|
| 303 | 0.15–0.35 | 0 | 90 % (excellent) | Poor | No* | 1.0× (base) | High-speed machining |
| 304 | ≤0.030 | 0 | 45 % (good) | Excellent | No* | 0.95× | General corrosion |
| 316 | ≤0.030 | 2–3 | 45 % (good) | Excellent | No* | 1.35× | Marine/chloride |
| 303Se | Se≥0.15 | 0 | 95 % (excellent) | Poor | No* | 1.1× | Ultra-smooth surface |
| 416 | ≥0.15 | 0 | 95 % (excellent) | Poor | Yes | 0.9× | Magnetic fasteners |
| 430F | ≥0.15 | 0 | 90 % (excellent) | Poor | Yes | 0.8× | Non-corrosive shafts |
*Non-magnetic in annealed condition; slight magnetism possible after cold work.
FAQ – 303 Stainless Steel Coil
-
What is the machinability rating of 303?
90 % (excellent) vs 45 % for 304 – chip break-up is superior, tool life 2–3× longer. -
Can 303 coil be welded?
Welding is not recommended due to hot-cracking risk; use 304 or 347 for welded joints and bolt on 303 parts. -
How does corrosion resistance compare with 304?
Slightly lower because of sulfur; adequate for indoor, food, and mild atmospheric service. -
What thickness tolerance do you guarantee?
ASTM A480/A895 standard; half-tolerance possible on request (±0.02 mm). -
How do I check current coil stock availability?
Login to our portal – live tonnage, coil ID, location, and certificate number updated every 30 minutes. -
What is the minimum order quantity?
One slit coil (≥500 kg) for stock items; master coils from 3 tons for mill direct. -
How often does the price change?
Linked to LME nickel and sulfur additive index – updated daily at 08:00 CST; fixed for 48 h after quotation. -
Which surface finishes are in stock?
2B, BA, No.4, HL, and micro-peeled; custom polishing up to Ra 0.1 µm available.
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