AISI 303 Stainless Steel Plate | 303 China steel mill-Direct Supply
What is AISI 303 Stainless Steel Plate?
As a professional China steel mill-Direct Supply and stainless steel plate supplier, SHH STEEL is pleased to present AISI 303 Stainless Steel Plate.
AISI 303 (UNS S30300) is a free-machining austenitic stainless steel developed from the basic 18-8 composition. By adding sulfur (or in some variants selenium), the grade achieves significantly improved machinability compared with standard Type 304. The sulfur forms manganese sulfide inclusions that act as chip breakers during machining, resulting in higher cutting speeds, better surface finish and longer tool life.
AISI 303 retains good corrosion resistance in mild environments, excellent toughness and non-magnetic properties in the annealed condition. It is widely used for parts that require extensive machining, such as shafts, fittings, fasteners, valve components and precision-turned parts.
SHH STEEL supplies AISI 303 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. We offer AISI 303 in plate and bar-related forms, with surface finishes suitable for subsequent machining and fabrication.
AISI 303 is frequently compared with a240 304, a240 304l and a240 316l when projects require a balance between machinability and corrosion performance. SHH STEEL provides technical support to help customers select the most suitable grade.
Material Specification
| Specification Element | Requirement | SHH STEEL Compliance |
|---|---|---|
| Grade | AISI 303 / UNS S30300 | 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 303 dual-certified to relevant ASTM/ASME specifications when required by the project.
Chemical Composition
Typical Chemical Composition of AISI 303 (UNS S30300):
| Element | Content (%) |
|---|---|
| Carbon (C) | ≤ 0.15 |
| Silicon (Si) | ≤ 1.00 |
| Manganese (Mn) | ≤ 2.00 |
| Phosphorus (P) | ≤ 0.20 |
| Sulfur (S) | ≥ 0.15 |
| Chromium (Cr) | 17.00 – 19.00 |
| Nickel (Ni) | 8.00 – 10.00 |
| Iron (Fe) | Balance |
The intentional sulfur addition (minimum 0.15%) is the key feature that provides the free-machining characteristics of AISI 303. While sulfur improves machinability, it slightly reduces corrosion resistance and weldability compared with standard a240 304. SHH STEEL carefully controls composition to meet both machinability and quality requirements.
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 303 offers mechanical properties similar to Type 304 in the annealed condition. The sulfur inclusions do not significantly affect strength but do improve chip breaking during machining. SHH STEEL supplies material with consistent mechanical properties suitable for precision machining applications.
Physical Properties
- Density: 7.93 g/cm³
- Magnetic Response: Non-magnetic in the annealed condition
- Melting Range: approximately 1400–1420°C
Material Comparison
| Grade | Machinability | Corrosion Resistance | Weldability | Typical Preference |
|---|---|---|---|---|
| AISI 303 | Excellent | Good | Limited | Free-machining parts |
| AISI 304 | Moderate | Better | Good | General purpose |
| AISI 304L | Moderate | Better | Excellent | Welded constructions |
| AISI 316L | Moderate | Excellent | Excellent | Chloride environments |
| AISI 416 | Excellent | Lower | Limited | Free-machining martensitic |
AISI 303 is the preferred choice when extensive machining is required. When better corrosion resistance or weldability is needed, SHH STEEL recommends upgrading to a240 304 or a240 304l. For higher corrosion resistance in chloride environments, a240 316l is the common selection.
Corrosion Resistance
AISI 303 offers good resistance to atmospheric corrosion, fresh water, food products and many mild chemical environments. However, the sulfur additions that improve machinability also create manganese sulfide inclusions that can act as initiation sites for pitting in more aggressive media.
Corrosion resistance is generally slightly lower than that of a240 304, particularly in chloride-containing or acidic environments. AISI 303 is therefore best suited for indoor or mildly corrosive service where machining productivity is the priority. SHH STEEL advises careful evaluation of the service environment before selecting 303 for critical corrosion applications.
For better pitting resistance, a240 316l or a240 2205 should be considered.
Weldability
AISI 303 has limited weldability compared with standard austenitic grades. The high sulfur content can cause 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 303 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. Because of the sulfur content, heat treatment practices should be carefully controlled.
Surface Finishes
| Finish | Description | Typical Use / Keywords |
|---|---|---|
| 2B | Cold-rolled, annealed, pickled, skin-passed | AISI 303 2B – general fabrication and machining |
| No.1 | Hot-rolled, annealed and pickled | AISI 303 No.1 – industrial plate |
| Special | Ground or custom finishes | AISI 303 Special – precision machining stock |
SHH STEEL regularly supplies AISI 303 in 2B and No.1 finishes suitable for subsequent machining operations.
Tolerances
Dimensional tolerances for AISI 303 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 303 is specifically chosen for components that require extensive machining. Typical applications of AISI 303 include:
| Industry / Sector | Typical Components / Equipment (with keywords) |
|---|---|
| Precision Machining | AISI 303 shafts, spindles, fittings, valve components |
| Fasteners & Hardware | AISI 303 screws, bolts, nuts, threaded parts |
| Automotive & Transportation | AISI 303 machined fittings and precision parts |
| Food & Beverage Equipment | AISI 303 machined components in mild environments |
| General Engineering | AISI 303 bushings, connectors, instrument parts |
| Pump & Valve Industry | AISI 303 valve stems, seats and machined bodies |
SHH STEEL supplies AISI 303 for these free-machining 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 303 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
- Flexible dimensions and surface finishes (including AISI 303 2B and AISI 303 No.1)
- Technical support for selection between free-machining and standard austenitic grades
- 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 303?The primary advantage is excellent machinability due to the sulfur addition. SHH STEEL recommends AISI 303 when high-volume or precision machining is required.
- How does AISI 303 compare with AISI 304 in corrosion resistance?AISI 303 has slightly lower corrosion resistance than 304 because of the sulfur inclusions. SHH STEEL advises using 304 or 316L when corrosion performance is critical.
- Can AISI 303 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 303 magnetic?Non-magnetic in the annealed condition. SHH STEEL supplies fully annealed material as standard.
- Does SHH STEEL supply dual-certified AISI 303 material?Yes, SHH STEEL commonly supplies dual-certified material upon request.
Conclusion
AISI 303 Stainless Steel Plate is a free-machining austenitic stainless steel designed for excellent machinability while retaining good corrosion resistance and toughness in mild environments. It is the preferred choice for shafts, fittings, fasteners, valve components and other parts that require extensive machining.
As a professional China steel mill-Direct Supply, SHH STEEL provides high-quality AISI 303 Stainless Steel Plate with competitive pricing, full certification and complete technical support.
Contact SHH STEEL today for stock availability, surface finish options (including AISI 303 2B and AISI 303 No.1), or a competitive quotation.
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