AISI 403 Stainless Steel Plate | A240 Type 403 | UNS S40300
What is AISI 403 Stainless Steel?
As a professional China steel mill-Direct Supply and stainless steel plate supplier, SHH STEEL is pleased to present AISI 403 Stainless Steel Plate.
AISI 403 is widely known and searched under many different names and designations, including AISI 403, ASTM A240 Type 403, ASME SA240 Type 403, UNS S40300, 403 stainless steel, 403 stainless steel plate, SUS403, turbine-quality 410 and high-quality 12% Cr 403. All these names refer to the same restricted-chemistry martensitic stainless steel based on Type 410.
AISI 403 contains 11.5–13.0% chromium with carbon up to 0.15%. Silicon is held lower than in standard A240 410, and residual elements are more tightly controlled. The result is a heat-treatable 12% Cr grade with more consistent hardenability, toughness and high-temperature integrity. It is magnetic in both the annealed and hardened conditions.
Typical uses include steam-turbine blades, compressor blades, high-integrity fasteners, valve parts and other components that need the corrosion resistance of 410 with cleaner chemistry. In the annealed condition AISI 403 can also be supplied as plate for later heat treatment.
SHH STEEL supplies AISI 403 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.
AISI 403 is frequently compared with A240 410, A240 410S, A240 430, A240 409, A240 429 and a240 304. SHH STEEL provides technical support to help customers choose the most appropriate 400-series grade.
Material Specification
| Specification Element | Requirement | SHH STEEL Compliance |
|---|---|---|
| Grade | AISI 403 / A240 Type 403 / UNS S40300 | Confirmed |
| Related Standards | ASTM A240, ASME SA240, ASTM A276 related, JIS SUS403 | Available |
| Product Form | Plate, Sheet, and heat-treatable flat products | Available |
| Delivery Condition | Annealed (hardened + tempered on request) | Standard annealed |
| Thickness Range | 1 mm – 80 mm (thicker available on request) | Custom sizes supported |
| Width | Up to 1500–2000 mm | Available |
| Length | Up to 6000–12000 mm or cut-to-length | Available |
| Surface Finish | No.1, 2B, and others on request | Available |
| Certification | EN 10204 3.1 / Mill Test Certificate | Available |
SHH STEEL can supply dual-certified ASTM A240 / ASME SA240 Type 403 material when required by the project.
Chemical Composition
Typical Chemical Composition of AISI 403 (UNS S40300):
| Element | Content (%) |
|---|---|
| Carbon (C) | ≤ 0.15 |
| Silicon (Si) | ≤ 0.50 |
| Manganese (Mn) | ≤ 1.00 |
| Phosphorus (P) | ≤ 0.040 |
| Sulfur (S) | ≤ 0.030 |
| Chromium (Cr) | 11.50 – 13.00 |
| Nickel (Ni) | ≤ 0.60 |
| Iron (Fe) | Balance |
The defining feature of AISI 403 is tighter chemistry than standard 410, especially lower silicon. This cleaner 12% Cr analysis improves consistency for turbine-quality heat treatment. Carbon remains high enough for martensitic hardening. SHH STEEL carefully controls residuals so AISI 403 meets high-integrity specifications.
Mechanical Properties
Annealed Condition (typical ASTM A240 values)
| Property | Value |
|---|---|
| Tensile Strength | ≥ 450 MPa (65 ksi) |
| Yield Strength (0.2%) | ≥ 205 MPa (30 ksi) |
| Elongation (in 50 mm) | ≥ 20% |
| Hardness | ≤ 217 HBW |
After quench and temper, AISI 403 can reach much higher strength and hardness, similar to Type 410, depending on tempering temperature. SHH STEEL normally supplies plate in the annealed condition unless a hardened-and-tempered condition is specified.
Physical Properties
Density is approximately 7.70–7.75 g/cm³. Melting range is approximately 1480–1530°C. The grade is magnetic in all common heat-treated conditions.
Material Comparison
| Grade | UNS | Chemistry Control | Hardenable | Typical Preference |
|---|---|---|---|---|
| AISI 403 | S40300 | Tighter than 410 | Yes | Turbine blades / high-integrity 12% Cr |
| AISI 410 | S41000 | Standard | Yes | General martensitic / wear service |
| AISI 410S | S41008 | Low carbon | Limited | Welded 12% Cr constructions |
| AISI 420 | S42000 | Higher carbon | Yes | Cutlery and high hardness |
| AISI 430 | S43000 | Ferritic | No | Appliances and general ferritic plate |
| AISI 304 | S30400 | Austenitic | No | General corrosion resistance |
AISI 403 is selected when the project needs 410-type hardenability with cleaner chemistry. For general wear parts, A240 410 is usually sufficient. For welded constructions that must stay soft, SHH STEEL recommends A240 410S.
Corrosion Resistance
AISI 403 offers moderate corrosion resistance similar to other 12% chromium martensitic grades. Best corrosion performance is obtained in the hardened and tempered condition with a clean, passive surface.
It resists mild atmospheres, steam and many petroleum-refining environments. It is not equivalent to a240 304 or a240 316l in chloride or acid service. For better atmospheric resistance without hardening, compare with A240 430.
Weldability
Weldability
AISI 403 has limited weldability because it can air-harden in the heat-affected zone, like Type 410. Preheat and post-weld heat treatment are often required, especially on thicker plate.
Matching 410/403 or appropriate martensitic fillers are used when welding is unavoidable. If extensive welding is the main fabrication method, SHH STEEL recommends A240 410S instead.
Heat Treatment
AISI 403 is normally supplied in the annealed condition by SHH STEEL and can be hardened by quench and temper.
Typical hardening is performed from about 925–1010°C, followed by oil or air cooling and tempering to the required strength or hardness. Annealing is used to soften plate for machining and forming. SHH STEEL can supply annealed plate or discuss hardened-and-tempered supply when the drawing requires it.
Surface Finishes
| Finish | Description | Typical Use / Keywords |
|---|---|---|
| No.1 | Hot-rolled, annealed and pickled | AISI 403 No.1 / A240 403 No.1 – industrial plate |
| 2B | Cold-rolled, annealed, pickled, skin-passed | AISI 403 2B – thinner plate and sheet |
| Special | Ground or custom finishes | AISI 403 Special – turbine / precision parts |
SHH STEEL regularly supplies AISI 403 in No.1 and 2B finishes. Ground surfaces can be arranged for high-integrity components.
Tolerances
Dimensional tolerances for AISI 403 Stainless Steel Plate supplied by SHH STEEL generally conform to ASTM A480 practices.
Typical available size range is thickness 1 mm – 80 mm, width up to 1500–2000 mm, and length up to 6000–12000 mm or cut-to-length. SHH STEEL provides precise dimensional control and can support tighter tolerances when required.
Equivalent Material Grades
| Grade / Designation | Standard / Region | Notes |
|---|---|---|
| AISI 403 | AISI | Main commercial keyword |
| A240 Type 403 | ASTM A240 / ASME SA240 | Plate specification |
| UNS S40300 | Unified Numbering System | Primary UNS designation |
| SUS403 | JIS (Japan) | Japanese equivalent |
| Related 1.4006 / X12Cr13 | EN (Europe) | Closest 12% Cr martensitic |
| Related 12Cr13 | GB/T (China) | Chinese related grade |
| Related 410 / 410S | Multiple | Standard / low-carbon variants |
Related grades for comparison include A240 410, A240 410S, A240 429, A240 430, A240 409 and a240 304.
Applications
AISI 403 is selected for high-integrity 12% Cr parts that will be heat treated. Typical applications of AISI 403 include:
| Industry / Sector | Typical Components / Equipment (with keywords) |
|---|---|
| Power Generation | AISI 403 steam turbine blades and compressor blades |
| Turbomachinery | AISI 403 discs, blades and high-integrity rotating parts |
| Valves & Pumps | AISI 403 stems, seats and heat-treated components |
| Oil & Gas / Refining | AISI 403 fasteners and wear-resistant 12% Cr parts |
| General Engineering | AISI 403 heat-treatable plate and cut parts |
| Industrial Equipment | A240 Type 403 No.1 plate for subsequent hardening |
SHH STEEL supplies AISI 403 for these high-integrity applications with consistent quality. For related industry solutions, see our energy industry, equipment manufacturing and machinery industry pages. Supporting services include steel cutting services, cnc steel machining services and steel welding 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 403 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)
- Tight-chemistry AISI 403 material suitable for turbine-quality 12% Cr service
- Flexible dimensions and surface finishes (including AISI 403 No.1 and AISI 403 2B)
- Technical support for selection among AISI 403, 410, 410S and 430
- 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 are the other common names for AISI 403?AISI 403 is also known as ASTM A240 Type 403, UNS S40300, SUS403 and turbine-quality 410. SHH STEEL can certify the required designation.
- What is the difference between AISI 403 and AISI 410?Both are 12% Cr martensitic grades. AISI 403 has tighter chemistry, especially lower silicon, and is preferred for turbine and high-integrity heat-treated parts. SHH STEEL supplies both grades.
- Can AISI 403 be hardened?Yes. Unlike 410S or 430, AISI 403 is designed to be quenched and tempered. SHH STEEL normally supplies annealed plate unless a hardened condition is specified.
- Is AISI 403 magnetic?Yes. It is magnetic in both the annealed and hardened conditions.
- What is the density of AISI 403?Approximately 7.70–7.75 g/cm³. SHH STEEL provides mill certificates confirming chemistry and mechanical properties.
- Is AISI 403 easy to weld?Weldability is limited because the heat-affected zone can harden. SHH STEEL recommends 410S when extensive welding is required.
- Does SHH STEEL supply dual-certified ASTM A240 Type 403 / AISI 403 material?Yes, SHH STEEL commonly supplies dual-certified material upon request.
Conclusion
AISI 403 Stainless Steel Plate is a high-quality 12% chromium martensitic grade with tighter chemistry than standard 410. It is the practical choice for steam-turbine blades, compressor parts and other heat-treatable components that need consistent hardenability and high-integrity performance.
As a professional China steel mill-Direct Supply, SHH STEEL provides high-quality AISI 403 Stainless Steel Plate with competitive pricing, full certification and complete technical support.
Contact SHH STEEL today for stock availability, surface finish options (including AISI 403 No.1 and AISI 403 2B), heat-treatment condition, or a competitive quotation.
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