AISI 420 Stainless Steel Plate | A240 Type 420 | UNS S42000
What is AISI 420 Stainless Steel?
As a professional China steel mill-Direct Supply and stainless steel plate supplier, SHH STEEL is pleased to present AISI 420 Stainless Steel Plate.
AISI 420 is widely known and searched under many different names and designations, including AISI 420, ASTM A240 Type 420, ASME SA240 Type 420, UNS S42000, 420 stainless steel, 420 stainless steel plate, SUS420J1, SUS420J2, 1.4021, 1.4028, X20Cr13, X30Cr13, 2Cr13 and 3Cr13. All these names refer to the high-carbon martensitic 12–14% chromium family used for hardness and wear resistance.
AISI 420 contains 12.0–14.0% chromium with a minimum of 0.15% carbon, higher than standard A240 410. The extra carbon allows much higher hardness after quench and temper. The grade is magnetic in both the annealed and hardened conditions.
Do not confuse AISI 420 / UNS S42000 with A240 UNS S42035, which is a separate low-carbon, titanium-bearing grade. This page covers the hardenable cutlery and wear grade S42000.
Typical uses include cutlery, surgical and dental instruments, molds, shear blades, pump parts and other components that must be hardened. In the annealed condition AISI 420 is supplied as plate or sheet for later machining and heat treatment.
SHH STEEL supplies AISI 420 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 420 is frequently compared with A240 410, A240 410S, A240 430, A240 429, A240 409 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 420 / A240 Type 420 / UNS S42000 | Confirmed |
| Related Standards | ASTM A240, ASME SA240, JIS SUS420J1/J2, EN 1.4021/1.4028 | Available |
| Product Form | Plate, Sheet | Available |
| Delivery Condition | Annealed (hardened + tempered on request) | Standard annealed |
| Thickness Range | 0.5 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 420 material when required by the project. Please confirm whether the drawing means S42000 or S42035.
Chemical Composition
Typical Chemical Composition of AISI 420 (UNS S42000):
| Element | Content (%) |
|---|---|
| Carbon (C) | ≥ 0.15 |
| Silicon (Si) | ≤ 1.00 |
| Manganese (Mn) | ≤ 1.00 |
| Phosphorus (P) | ≤ 0.040 |
| Sulfur (S) | ≤ 0.030 |
| Chromium (Cr) | 12.00 – 14.00 |
| Nickel (Ni) | ≤ 0.75 |
| Iron (Fe) | Balance |
The defining feature of AISI 420 is carbon of at least 0.15% in a 12–14% chromium martensitic base. Higher carbon produces higher hardness after heat treatment. Related shop grades include 420J1 (about 0.16–0.25% C) and 420J2 (about 0.26–0.40% C). SHH STEEL can match the carbon range required by the specification.
Mechanical Properties
Annealed Condition (typical ASTM A240 values for Type 420)
| Property | Value |
|---|---|
| Tensile Strength | ≤ 690 MPa (100 ksi) maximum |
| Elongation (in 50 mm) | ≥ 15% |
| Hardness | ≤ 217 HBW |
ASTM A240 lists a maximum tensile strength for Type 420 in the annealed condition because the grade is intended for later heat treatment. After quench and temper, hardness can reach approximately 50 HRC depending on carbon content and tempering temperature. SHH STEEL normally supplies plate in the annealed condition unless a hardened-and-tempered condition is specified.
Physical Properties
Density is approximately 7.75 g/cm³. Melting range is approximately 1450–1510°C. The grade is magnetic in all common heat-treated conditions.
Material Comparison
| Grade | UNS | Carbon | Hardenable | Typical Hardness Use | Typical Preference |
|---|---|---|---|---|---|
| AISI 410 | S41000 | ≤ 0.15 | Yes | Moderate | Valves, pumps, general wear |
| AISI 420 | S42000 | ≥ 0.15 | Yes | High | Cutlery, tools, surgical instruments |
| AISI 410S | S41008 | ≤ 0.08 | Limited | Low | Welded 12% Cr constructions |
| S42035 | S42035 | ≤ 0.08 | No | Low | Welded plate, not a cutlery grade |
| AISI 430 | S43000 | ≤ 0.12 | No | Low | Appliances and ferritic plate |
| AISI 304 | S30400 | ≤ 0.08 | No | Low | General corrosion resistance |
AISI 420 is selected when high hardness after heat treatment is required. It should not be substituted for S42035 or A240 410S in welded constructions that must stay soft. For general 12% Cr wear parts with lower hardness, A240 410 is often sufficient.
Corrosion Resistance
AISI 420 offers moderate corrosion resistance typical of 12–14% chromium martensitic steels. Best performance is obtained in the hardened and tempered condition with a clean, passive, polished surface.
It resists mild atmospheres, fresh water, steam and many food-contact environments when properly heat treated. It is not equivalent to a240 304 or a240 316l in chloride or acid service. Maximum corrosion resistance is reduced if the steel is left in the annealed condition.
Weldability
AISI 420 has poor to limited weldability because high carbon causes a hard, brittle heat-affected zone. Preheat and post-weld heat treatment are normally required if welding cannot be avoided.
Matching 420 fillers may be used for repair welds. If extensive welding is the main fabrication method, SHH STEEL recommends A240 410S or an austenitic grade instead.
Heat Treatment
AISI 420 is normally supplied in the annealed condition by SHH STEEL and is designed to be hardened by quench and temper.
Typical hardening is performed from about 980–1050°C, followed by oil or air cooling and tempering to the required hardness. Higher carbon versions such as 420J2 reach higher 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 420 No.1 / A240 420 No.1 – industrial plate |
| 2B | Cold-rolled, annealed, pickled, skin-passed | AISI 420 2B – thinner plate and sheet |
| Special | Ground or polished | AISI 420 polished – cutlery and instrument blanks |
SHH STEEL regularly supplies AISI 420 in No.1 and 2B finishes. Ground or polished surfaces can be arranged for cutlery and instrument stock.
Tolerances
Dimensional tolerances for AISI 420 Stainless Steel Plate supplied by SHH STEEL generally conform to ASTM A480 practices.
Typical available size range is thickness 0.5 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 420 | AISI | Main commercial keyword |
| A240 Type 420 | ASTM A240 / ASME SA240 | Plate specification |
| UNS S42000 | Unified Numbering System | Primary UNS designation |
| 1.4021 / X20Cr13 | EN (Europe) | Lower-carbon 420 / 420J1 |
| 1.4028 / X30Cr13 | EN (Europe) | Higher-carbon 420 / 420J2 |
| SUS420J1 / SUS420J2 | JIS (Japan) | Japanese 420 family |
| 2Cr13 / 3Cr13 | GB/T (China) | Chinese equivalents |
Related grades for comparison include A240 410, A240 410S, A240 429, A240 430, A240 409 and a240 304.
Applications
AISI 420 is selected for parts that must be hardened to high hardness. Typical applications of AISI 420 include:
| Industry / Sector | Typical Components / Equipment (with keywords) |
|---|---|
| Cutlery & Kitchen Tools | AISI 420 knife blades, scissors and cutting tools |
| Medical & Dental | AISI 420 surgical and dental instruments |
| Molds & Dies | AISI 420 plastic molds and wear inserts |
| Valves & Pumps | AISI 420 seats, shafts and hardened wear parts |
| General Engineering | AISI 420 shear blades, guides and machined wear components |
| Industrial Equipment | A240 Type 420 No.1 plate for subsequent hardening |
SHH STEEL supplies AISI 420 for these heat-treatable applications with consistent quality. For related industry solutions, see our equipment manufacturing and machinery industry pages. Supporting services include steel cutting services, cnc steel machining services and worldwide shipping service.
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 420 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)
- High-carbon AISI 420 material optimized for hardening to cutlery and wear hardness
- Flexible dimensions and surface finishes (including AISI 420 No.1 and AISI 420 2B)
- Technical support for selection among AISI 410, 420, 420J1/J2 and 410S
- 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 420?AISI 420 is also known as ASTM A240 Type 420, UNS S42000, SUS420J1, SUS420J2, 1.4021, 1.4028, X20Cr13, X30Cr13, 2Cr13 and 3Cr13. SHH STEEL can certify the required designation.
- What is the difference between AISI 420 and AISI 410?AISI 420 has higher carbon (≥ 0.15%) and can reach much higher hardness. 410 is used for general wear and valves; 420 is used for cutlery and tools. SHH STEEL supplies both grades.
- Is AISI 420 the same as UNS S42035?No. S42000 is the hardenable cutlery grade. S42035 is a low-carbon, titanium-bearing A240 grade for welded plate. SHH STEEL asks customers to confirm the UNS number before production.
- Can AISI 420 be hardened?Yes. That is its main purpose. SHH STEEL normally supplies annealed plate unless a hardened condition is specified.
- Is AISI 420 magnetic?Yes. It is magnetic in Approximately 7.75 g/cm³. SHH STEEL provides mill certificates confirming chemistry and mechanical properties.both the annealed and hardened conditions.
- What is the density of AISI 420?Approximately 7.75 g/cm³. SHH STEEL provides mill certificates confirming chemistry and mechanical properties.
- Does SHH STEEL supply dual-certified ASTM A240 Type 420 / AISI 420 material?Yes, SHH STEEL commonly supplies dual-certified material upon request.
Conclusion
AISI 420 Stainless Steel Plate is the standard high-carbon 12–14% chromium martensitic grade for cutlery, surgical instruments, molds and wear parts. It is chosen when high hardness after quench and temper is required, not when the project needs a soft welded 12% Cr plate.
As a professional China steel mill-Direct Supply, SHH STEEL provides high-quality AISI 420 Stainless Steel Plate with competitive pricing, full certification and complete technical support.
Contact SHH STEEL today for stock availability, carbon range (420 / 420J1 / 420J2), surface finish options (including AISI 420 No.1 and AISI 420 2B), or a competitive quotation.
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