Introduction
AISI 420 stainless steel coil is a versatile and cost-effective, martensitic stainless steel known for its good combination of strength, hardness, moderate corrosion resistance, and excellent formability. This high-carbon variation of AISI 410 offers additional benefits when heat treatment is involved.
Composition
The key elements in AISI 420 are:
Chromium (12% min): Provides the foundation for corrosion resistance and contributes to the martensitic microstructure.
Carbon (0.3% - 0.4%): The higher carbon content compared to 410 allows for significant hardening through heat treatment.
Manganese (less than 1%) and Silicon (less than 1%) are also present in small amounts, influencing its properties.
Characteristics
Moderate Corrosion Resistance: AISI 420 offers adequate protection in mildly corrosive environments, particularly indoors or with good surface finishing and maintenance. It performs better than non-stainless steels but is not as corrosion resistant as austenitic stainless steels like 304.
High Strength and Hardness: Compared to both ferritic (like 409L) and standard martensitic grades (like 410), 420 offers superior strength and hardness due to its higher carbon content and potential for heat treatment. This makes it a good choice for wear-resistant applications.
Excellent Formability: AISI 420 exhibits exceptional formability in its annealed condition, allowing for shaping and drawing during fabrication. This characteristic makes it suitable for applications requiring complex bends and intricate shapes.
Magnetic: AISI 420 is magnetic in all conditions.
Weldability: AISI 420 can be welded, but due to its martensitic structure and higher carbon content, it's more susceptible to weld cracking compared to austenitic steels. Careful welding procedures and post-weld heat treatment might be necessary to maintain good mechanical properties and corrosion resistance in the weld zone.
Uses
Due to its affordability, good combination of strength, corrosion resistance, and exceptional formability, AISI 420 stainless steel coil finds application in various industries, including:
Cutlery: Knife blades, particularly budget-friendly options, can be made from 420 due to its good balance of hardness, corrosion resistance, and affordability. Higher-grade stainless steels are used for premium cutlery.
Aerospace Parts: Certain non-critical aerospace components, such as landing gear parts or engine parts that require good formability, can utilize 420 for its strength and affordability.
Medical Instruments: Some non-implant surgical instruments can benefit from the strength, formability, and affordability of 420. For implantable devices, higher-grade stainless steels are recommended.
Automotive Parts: Gears, shafts, valve components, and other wear-resistant components can utilize 420 for its strength and affordability, especially in less critical applications.
Springs: Due to its good formability and ability to be hardened through heat treatment, 420 can be used in certain spring applications requiring moderate corrosion resistance.
Product Specifications
| Specification | Description |
| Grades | 304. 304L, 316. 316L, 310S, 321. 410. 430. and more |
| Thickness | Ranges from 0.1mm to 20mm |
| Width | From 600mm to 1500mm, catering to specific project needs |
| Weight | Coils can be supplied in standard and custom weights, depending on customer requirements |
| Surface Finishes | 2B (mill finish), BA (bright annealed), No.4 (brushed), Mirror (reflective finish), and Satin (soft sheen finish) |
| Surface Treatments | Annealing, Pickling, Passivation, and Polishing for enhanced corrosion resistance and appearance |
Additional Points
AISI 420 comes in various standard specifications, such as ASTM A240/ASME SA240. ensuring consistent material properties.
Several variations of AISI 420 exist, such as 420HC (higher carbon content) and 420J2 (added sulfur for improved machinability). The specific type of 420 chosen depends on the desired balance of properties for the application.
When selecting between 420 and other stainless steel grades, consider the specific application's requirements for strength, corrosion resistance, formability, and budget. For superior corrosion resistance, austenitic steels might be a better choice. For applications demanding the highest strength and hardness, even higher-grade martensitic steels could be an option.
