AISI 303Cu Stainless Steel Plate | 303Cu China steel mill-Direct Supply
What is AISI 303Cu Stainless Steel Plate?
As a professional China steel mill-Direct Supply and stainless steel plate supplier, SHH STEEL is pleased to present AISI 303Cu Stainless Steel Plate.
AISI 303Cu is a free-machining austenitic stainless steel based on the 18-8 composition, with intentional copper addition. Copper further enhances machinability and improves cold formability compared with standard sulfur- or selenium-bearing 303 grades. The grade retains good corrosion resistance in mild environments, excellent toughness and non-magnetic properties in the annealed condition.
AISI 303Cu is particularly suitable for components that require both high-volume machining and subsequent cold forming or heading operations. Typical applications include precision-turned parts, fasteners, fittings, shafts and other machined components where improved formability is an advantage.
SHH STEEL supplies AISI 303Cu as true China steel mill-Direct Supply, sourcing directly from major Chinese stainless steel mills. This model delivers competitive mill pricing, consistent quality, complete heat traceability and reliable delivery. SHH STEEL offers AISI 303Cu in plate and related forms with surface finishes suitable for subsequent machining and forming.
AISI 303Cu is frequently compared with a240 304, a240 304l and a240 316l when projects require an optimal balance of machinability, formability and corrosion performance. SHH STEEL provides technical support to help customers select the most suitable free-machining grade.
Material Specification
| Specification Element | Requirement | SHH STEEL Compliance |
|---|---|---|
| Grade | AISI 303Cu / UNS S30330 | Confirmed |
| Related Standards | ASTM A240, ASTM A582, ASME, JIS, EN related | Available |
| Product Form | Plate, Sheet, Bar (related) | Available |
| Delivery Condition | Annealed | Standard |
| Thickness Range | 0.5 mm – 50 mm (thicker available on request) | Custom sizes supported |
| Width | Up to 1500–2000 mm | Available |
| Length | Up to 6000 mm or cut-to-length | Available |
| Surface Finish | 2B, No.1, and others on request | Available |
| Certification | EN 10204 3.1 / Mill Test Certificate | Available |
SHH STEEL can supply AISI 303Cu dual-certified to relevant ASTM/ASME specifications when required by the project.
Chemical Composition
Typical Chemical Composition of AISI 303Cu:
| Element | Content (%) |
|---|---|
| Carbon (C) | ≤ 0.15 |
| Silicon (Si) | ≤ 1.00 |
| Manganese (Mn) | ≤ 2.00 |
| Phosphorus (P) | ≤ 0.20 |
| Sulfur (S) | ≥ 0.15 (typical) |
| Copper (Cu) | 1.50 – 3.50 |
| Chromium (Cr) | 17.00 – 19.00 |
| Nickel (Ni) | 8.00 – 10.00 |
| Iron (Fe) | Balance |
The intentional copper addition (typically 1.5–3.5%) is the key differentiating feature of AISI 303Cu. Copper improves machinability and cold formability while helping to maintain acceptable corrosion resistance in mild environments. SHH STEEL carefully controls the composition to ensure consistent free-machining performance.
Mechanical Properties
Annealed Condition (typical values)
| Property | Value |
|---|---|
| Tensile Strength | ≥ 515 MPa (75 ksi) |
| Yield Strength (0.2%) | ≥ 205 MPa (30 ksi) |
| Elongation (in 50 mm) | ≥ 40% |
| Hardness | ≤ 217 HB |
AISI 303Cu offers mechanical properties similar to standard 303 and Type 304 in the annealed condition. The copper addition provides a modest improvement in cold formability, making the grade more suitable for operations that combine machining with subsequent forming. SHH STEEL supplies material with consistent mechanical properties for precision machining and forming applications.
Physical Properties
- Density: approximately 7.93–8.00 g/cm³
- Magnetic Response: Non-magnetic in the annealed condition
- Melting Range: approximately 1400–1420°C
Material Comparison
| Grade | Key Alloying Difference | Ni (%) | Cr (%) | Mo (%) | Free-Machining Element | Machinability | Formability | Corrosion Resistance | Typical Preference |
|---|---|---|---|---|---|---|---|---|---|
| AISI 303 | Sulfur addition | 8.0–10.0 | 17.0–19.0 | — | Sulfur | Excellent | Good | Good | General free-machining |
| AISI 303Se | Selenium addition | 8.0–10.0 | 17.0–19.0 | — | Selenium | Excellent | Good | Slightly better | Precision machining + better finish |
| AISI 303Cu | Copper addition | 8.0–10.0 | 17.0–19.0 | — | Sulfur + Copper | Excellent | Better | Good | Machining + improved cold formability |
| AISI 304 | Standard 18-8 | 8.0–10.5 | 18.0–20.0 | — | None | Moderate | Excellent | Better | General purpose |
| AISI 304L | Extra-low carbon | 8.0–12.0 | 18.0–20.0 | — | None | Moderate | Excellent | Better | Heavy welding |
| AISI 316L | Molybdenum addition | 10.0–14.0 | 16.0–18.0 | 2.0–3.0 | None | Moderate | Excellent | Excellent | Chloride environments |
AISI 303Cu differs from standard 303 primarily through the addition of copper, which improves cold formability while retaining excellent machinability. Compared with a240 304 and a240 304l, it offers superior machinability at the expense of slightly lower corrosion resistance. Unlike a240 316l, it contains no molybdenum and is therefore not intended for chloride-rich environments. SHH STEEL recommends AISI 303Cu when both high machining productivity and improved cold formability are required.
Corrosion Resistance
AISI 303Cu offers good resistance to atmospheric corrosion, fresh water, food products and many mild chemical environments. The copper addition has a neutral to slightly beneficial effect on corrosion performance in many media compared with standard sulfur-bearing 303.
Corrosion resistance remains lower than that of a240 304 in more aggressive conditions, particularly in chloride-containing environments. AISI 303Cu is best suited for indoor or mildly corrosive service where machining productivity and formability are priorities. SHH STEEL advises careful evaluation of the service environment before selecting 303Cu for critical corrosion applications.
For better pitting resistance, a240 316l or a240 2205 should be considered.
Weldability
AISI 303Cu has limited weldability. The free-machining additions (sulfur and copper) increase the risk of hot cracking and porosity in the weld zone. Welding is generally not recommended for critical applications.
When welding cannot be avoided, low heat input and appropriate filler metals should be used, followed by careful post-weld cleaning. For components that require both machining and welding, SHH STEEL often recommends machining from a240 304l or using a combination of free-machining and weldable grades.
Heat Treatment
AISI 303Cu is normally supplied in the annealed condition by SHH STEEL.
Recommended Solution Annealing Parameters
- Temperature range: 1010 – 1120°C
- Cooling: Rapid cooling (water quench preferred)
Annealing softens the material after cold working and optimizes corrosion resistance. SHH STEEL controls heat treatment to ensure consistent properties for machining and forming stock.
Surface Finishes
| Finish | Description | Typical Use / Keywords |
|---|---|---|
| 2B | Cold-rolled, annealed, pickled, skin-passed | AISI 303Cu 2B – general fabrication and machining |
| No.1 | Hot-rolled, annealed and pickled | AISI 303Cu No.1 – industrial plate |
| Special | Ground or custom finishes | AISI 303Cu Special – precision machining stock |
SHH STEEL regularly supplies AISI 303Cu in 2B and No.1 finishes suitable for subsequent machining and forming operations.
Tolerances
Dimensional tolerances for AISI 303Cu Stainless Steel Plate supplied by SHH STEEL generally conform to ASTM A480 practices.
Typical available size range:
- Thickness: 0.5 mm – 50 mm
- Width: up to 1500–2000 mm
- Length: up to 6000 mm or cut-to-length
SHH STEEL provides precise dimensional control and can support tighter tolerances when required for machining stock.
Applications
AISI 303Cu is specifically chosen for components that require both excellent machinability and improved cold formability. Typical applications of AISI 303Cu include:
| Industry / Sector | Typical Components / Equipment (with keywords) |
|---|---|
| Precision Machining | AISI 303Cu shafts, spindles, fittings, valve components |
| Fasteners & Hardware | AISI 303Cu screws, bolts, nuts, cold-headed parts |
| Automotive & Transportation | AISI 303Cu machined and formed fittings |
| Food & Beverage Equipment | AISI 303Cu machined components in mild environments |
| General Engineering | AISI 303Cu bushings, connectors, instrument parts |
| Pump & Valve Industry | AISI 303Cu valve stems, seats and machined bodies |
SHH STEEL supplies AISI 303Cu for these free-machining and forming applications with consistent quality. For related industry solutions, see our equipment manufacturing and machinery industry pages. Supporting services include steel cutting services and cnc steel machining services.
Why Choose SHH STEEL
SHH STEEL is a China steel mill-Direct Supply specializing in stainless steel plate and sheet. By working directly with major Chinese stainless steel mills, SHH STEEL supplies AISI 303Cu with the following advantages:
- Genuine China steel mill-Direct Supply pricing
- Consistent quality and complete heat traceability
- Full Mill Test Certificates (EN 10204 3.1)
- Material optimized for free-machining performance and improved formability
- Flexible dimensions and surface finishes (including AISI 303Cu 2B and AISI 303Cu No.1)
- Technical support for selection among free-machining 303 variants
- Value-added services including steel cutting services, cnc steel machining services and worldwide shipping service
For more information about our company and full product range, please visit China steel Mill Agent-SHH STEEL.
FAQ
- What is the main advantage of AISI 303Cu over standard AISI 303?The copper addition improves cold formability while retaining excellent machinability. SHH STEEL recommends 303Cu when both high machining productivity and subsequent cold forming are required.
- How does AISI 303Cu compare with AISI 304 in corrosion resistance?AISI 303Cu has slightly lower corrosion resistance than 304 because of the free-machining additions. SHH STEEL advises using 304 or 316L when corrosion performance is critical.
- Can AISI 303Cu be welded?Welding is possible but not recommended for critical applications due to the risk of hot cracking. SHH STEEL suggests alternative grades when welding is required.
- Is AISI 303Cu magnetic?Non-magnetic in the annealed condition. SHH STEEL supplies fully annealed material as standard.
Conclusion
AISI 303Cu Stainless Steel Plate is a copper-bearing free-machining austenitic stainless steel designed for excellent machinability combined with improved cold formability and good corrosion resistance in mild environments. It is the preferred choice for shafts, fittings, fasteners, valve components and other parts that require both extensive machining and subsequent forming operations.
As a professional China steel mill-Direct Supply, SHH STEEL provides high-quality AISI 303Cu Stainless Steel Plate with competitive pricing, full certification and complete technical support.
Contact SHH STEEL today for stock availability, surface finish options (including AISI 303Cu 2B and AISI 303Cu No.1), or a competitive quotation.
AISI 303Cu Stainless Steel Plate, 303Cu China steel mill-Direct Supply, AISI 303Cu, 303Cu Stainless Steel Plate, UNS S30330, AISI 303Cu supplier
Quality Steel Needed? Inquire for Offers
Related Products
