Contents
420 Stainless Steel: Definition, Composition, Properties, Applications and More
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420 stainless steel stands out for its ability to maintain a sharp edge while offering good corrosion resistance. It is used in many applications that demand durability and precision. In this article, we will look at the key features of 420 stainless steel and its typical applications, and understand everything about it.
What is 420 Stainless Steel?
420 stainless steel is also called UNS S42000. It is a family of martensitic stainless steel. It is composed of approximately 85-88% iron, 12-14% chromium, and 0.15-0.45% carbon. It has high hardness and wear resistance. It is ideal for cutting tools, medical instruments, industrial gears, and automotive components. lt can be categorized into different types like 420J1 and 420J2.
Equivalents of 420 Stainless Steel
There are several equivalents of 420 stainless steel depending on the standards and countries.
- S42000 ( Unified Numbering System)
- 1.4021 ( European Standard)
- AISI 420 ( American Iron and Steel Institute)
- 1.4021 ( German Standard)
- SUS420J1 and SUS420J2 ( Japanese Standard)
Standards of 420 Stainless Steel
- ASTM A276
- ASTM A240/A240M
- ASTM A580/A580M
Subgroups of 420 Stainless Steel
420 stainless steel can be classified into various subgroups based on its carbon content and specific properties.
420J1
Carbon Content: Lower (approximately 0.15-0.25%)
Properties: Offers good corrosion resistance with moderate hardness.
Applications: It is used in situations where toughness is prioritized over hardness. This includes cutlery and surgical instruments.
420J2
Carbon Content: Higher (approximately 0.26-0.40%)
Properties: Provides higher hardness and wear resistance. But it has slightly less corrosion resistance than 420J1.
Applications: It is suitable for applications requiring better wear resistance. This includes knife blades, scissors, and industrial blades.
What Elements Make Up 420 Stainless Steel？
Check the table below for the chemical composition of 420 stainless steels:
| Element | Percentage (%) |
| Iron (Fe) | Balance (approx. 85-88) |
| Carbon (C) | 0.15-0.45 |
| Chromium (Cr) | 12-14 |
| Manganese (Mn) | Up to 1 |
| Silicon (Si) | Up to 1 |
| Phosphorus (P) | Up to 0.04 |
| Sulfur (S) | Up to 0.03 |
Physical Properties of 420 Stainless Steel
Check the table below for the physical properties of 420 stainless steels:
| Property | Typical Value (Metric) |
| Density | 7.75 g/cm³ (0.28 lb/in³) |
| Electrical Conductivity | 1.4 x 10⁶ S/m |
| Magnetic Properties | Magnetic |
Is 420 Stainless Steel Magnetic?
Yes, 420 stainless steel is magnetic. It belongs to the class of martensitic stainless steel, which is magnetic. The iron in 420 stainless steel makes it magnetic, and it can be hardened through heat treatment. If you need hard and magnetic stainless steel, 420 is a good choice.
Related Reading
Is Stainless Steel Magnetic?
Thermal Properties of 420 Stainless Steel
Check the table below for the thermal properties of 420 stainless steels:
| Property | Typical Value |
| Melting Point | 1450°C (2642°F) |
| Thermal Conductivity | 24.9 W/m·K (14.4 BTU/ft·h·°F) |
| Thermal Expansion | 10.3 µm/m·°C (5.7 µin/in·°F) |
| Specific Heat Capacity | 460 J/kg·K (0.11 BTU/lb·°F) |
Mechanical Properties of 420 Stainless Steel
Check the table below for the mechanical properties of 420 stainless steels:
| Property | Value |
| Tensile Strength | 620-750 MPa |
| Yield Strength | 345-415 MPa |
| Brinell Hardness (HB) | 207-235 |
| Rockwell Hardness (HRC) | 50 |
| Vickers Hardness (HV) | 540 |
| Elongation | 20% |
| Elastic Modulus | 200 GPa |
420 Stainless Steel Hardness
The hardness of 420 stainless steel can vary depending on the heat treatment process, but it typically ranges between 48-56 HRC (Rockwell Hardness).
In its annealed state, it has a lower hardness, but after proper hardening and tempering, it can reach the upper end of this range.
Corrosion Resistance
420 stainless steel has 12-14% chromium content. It has good corrosion resistance. But it has lower corrosion resistance than stainless steels like 304 or 316. It performs well in freshwater, mild chemicals, and normal atmospheric conditions. However, it is less effective in highly acidic or salty environments.
420 stainless steel is ideal for cutlery, kitchen tools, and medical instruments due to corrosion resistance. It is also used in industrial machinery and automotive parts, where durability and resistance to wear are important.
Heat Resistance
420 stainless steel can resist heat. It is suitable for applications at moderate temperatures up to about 700°C (1292°F). At these temperatures, 420 stainless steel resists scaling and oxidation. It is suitable for automotive exhaust systems and other components regularly subjected to heat.
But in environments with extreme temperatures, other stainless steels like 310 or 316 may perform better.
Proper heat treatment can optimize the heat resistance of 420 stainless steel. These treatments help the steel retain its hardness and strength after repeated heating and cooling cycles.
What are the 420 Stainless Steel Used for?
Here are some common applications:
- Cutlery and Kitchen Tools
Ideal for knives and cutting tools because of their high hardness and sharp edge retention.
- Surgical Instruments
Suitable for medical instruments that need to stay sharp and withstand sterilization.
- Industrial Components
Used in machinery parts such as valves, pump shafts, and gears that require wear resistance and high strength.
- Automotive Parts
Components like springs and valves benefit from its strength and durability.
- Food Processing Equipment
Resistant to food acids and easy to clean, making it ideal for blades and slicers.
The Advantages of 420 Stainless Steel
- High Hardness and Strength
420 stainless steel is capable of being hardened to achieve high strength. This makes it suitable for cutting equipment, industrial machinery, and surgical scalpels.
- Good Wear Resistance
It has great resistance to wear and abrasion. This is beneficial for applications requiring prolonged use and durability.
- Cost-Effective
420 can offer good performance at a lower cost than other stainless steel like 316.
The Disadvantages of 420 Stainless Steel
- Moderate Corrosion Resistance
420 stainless steel offers lower corrosion resistance than 304 or 316. It may be easier to corrosion, particularly in highly corrosive environments.
- Poor Weldability
Because of the necessity to prevent cracking, welding 420 stainless steel needs to carefully preheat and post-weld heat treatment. So the process can be more complex
- Limited Cold Workability
The high hardness of 420 stainless steel makes it less suitable for extensive cold-forming operations, as it can lead to cracking.
- Heat Sensitivity
420 stainless steel has limited resistance to high temperatures compared to other grades. It may lose strength or deform if exposed to extreme heat.
420 Stainless Steel Heat treatment
Annealing
Heat the steel to a high temperature. After that slowly cool. It can relieve internal stresses and improve ductility.
Hardening
The steel is heated to 980-1065°C (1796-1949°F) and then rapidly cooled (quenched) in oil or air. It can increase hardness.
Tempering
Reheat the hardened steel to 150-370°C (302-698°F) to achieve the balance of hardness and toughness needed.
420 Stainless Steel Tempering Chart
Here is a general tempering chart for 420 stainless steel. It shows the relationship between tempering temperature and the resulting hardness.
| Temperature | Temperature | Hardness |
| 150°C | 302°F | 54-56 HRC |
| 200°C | 392°F | 52-54 HRC |
| 250°C | 482°F | 50-52 HRC |
| 300°C | 572°F | 48-50 HRC |
| 400°C | 752°F | 45-47 HRC |
| 500°C | 932°F | 40-42 HRC |
| 600°C | 1112°F | 35-37 HRC |
The Processing Methods of 420 Stainless Steel
Hot Working
- Hot Rolling
Performed at temperatures between 1100°C and 900°C (2012°F to 1652°F) to shape the steel into plates, sheets, or bars.
- Forging
The steel can be hot forged within the same temperature range to produce custom shapes and sizes.
Cold Working
- Cold Drawing
The steel is drawn through a die to reduce its cross-sectional area, improving surface finish and mechanical properties.
Commonly used for producing wires, bars, and tubes with precise dimensions.
- Cold Forming
The steel is shaped at room temperature to achieve specific forms or dimensions.
Increases strength and hardness due to work hardening.
- Considerations: Excessive deformation may cause cracking due to limited ductility.
Machining
Best performed in the annealed condition when the steel is softer.
The steel can be machined using carbide or high-speed steel tools, with proper coolant and lubrication.
Welding
Preheat the steel to 150–320°C (302–608°F) to reduce the risk of cracking.
Use compatible filler materials, such as AWS E/ER420 or austenitic stainless fillers.
Perform annealing or tempering after welding to relieve stresses and reduce hardness.
Grinding and Polishing
Achieving precise dimensions and a smooth surface finish.
Essential for products like cutlery and surgical instruments where sharpness and aesthetics are important.
Finishes
Surface Treatments: Processes like passivation, electro-polishing, or coating to enhance corrosion resistance and appearance.
Coatings: Application of protective layers such as nitriding or Physical Vapor Deposition (PVD) to improve surface hardness and wear resistance.
Wire Finishes
Specific to wire products, including:
- Bright Finish: Achieved through controlled annealing and surface treatments for a shiny appearance.
- Matte Finish: Produced by mechanical descaling or acid pickling for a dull surface.
- Plating: Applying metals like zinc or tin for additional corrosion protection.
- Lubrication Coatings: For wires intended for further cold forming or drawing.
The Differences Between 420 Stainless Steel and Other Stainless Steel
440 VS 420
- 420 stainless steel has 12-14% chromium and 0.15-0.40% carbon. It is softer, with a hardness of 50-54 HRC. 440 stainless steel has more chromium (16-18%) and higher carbon (0.6-1.2%), giving it a hardness of 58-62 HRC. This makes 440 harder and more durable.
- 440 resists high temperatures better, making it less likely to warp compared to 420.
- 420 is easier to machine and weld.
- 440 stainless steel is more expensive.
410(UNS S41000) VS 420
- 410 stainless steel contains 11.5-13.5% chromium and 0.08-0.15% carbon. 420 stainless steel has 12-14% chromium and 0.15-0.40% carbon, making it harder and stronger than 410.
- 420 has better wear resistance and the ability to hold a sharper edge because it has a higher carbon content.
- 410 stainless steel performs better heat resistance. At high temperatures up to 650°C, 420 is more prone to losing mechanical properties at elevated temperatures.
- 410 stainless steel is easier to machine and weld. Because it has lower carbon content. It is also more affordable than 420 stainless steel.
- 410 stainless steel is used in cutlery, steam turbine blades, and automotive parts. 420 stainless steel is used for cutting equipment, industrial machinery, and surgical scalpels.
316 VS 420
- 316 stainless steel has 16-18% content of chromium, 10-14% content of nickel, and 2-3% content of molybdenum. This composition gives 316 superior corrosion resistance but makes it less hard than 420.
- 316 stainless steel withstands higher temperatures, maintaining its properties up to around 870°C (1598°F). 420 stainless steel handles up to about 700°C (1292°F) but loses its mechanical properties at higher temperatures.
- 420 stainless steel is easier to machine because of its lower hardness. 316 stainless steel costs more because it contains more nickel and molybdenum content.
- 316 stainless steel is used in marine environments, chemical processing, and food industry applications. 420 stainless steel is used in cutlery, surgical scalpels, blades, and industrial machinery.
The Various Forms of 420 Stainless Steel
Here are the most common forms for different applications.
Sheet
420 stainless steel sheets are flat and thin, typically between 0.5 mm and 3 mm thick. They are used in applications like kitchen tools and surgical instruments.
Bar
Bars can be cylindrical or rectangular solid pieces. They are often used in machining, forging, and other fabrication processes to create parts like gears, shafts, and fasteners.
Plate
Plates are thicker than sheets, usually over 6 mm thick. They are used in heavy-duty applications like structural components and industrial machinery.
Strip
Strips are thin, flat pieces similar to sheets but typically narrower. They are used in the manufacture of springs, blades, and other components requiring precise dimensions and flexibility.
Wire
420 stainless steel wire is used in applications that require fine, flexible material, such as in medical devices, springs, and certain types of fasteners.
Other Things You Should Know About 420 Stainless Steel
Is 420 Stainless Steel Good?
Yes, 420 stainless steel is good for applications requiring high hardness and moderate corrosion resistance, such as knives, surgical instruments, and dental tools.
Is 420 Stainless Steel Good for Knives?
Yes, 420 stainless steel is good for knives; it offers decent hardness and corrosion resistance, making it suitable for budget-friendly blades and cutlery.
Is 420 Stainless Steel Magnetic?
Yes, 420 stainless steel is magnetic because it is a martensitic stainless steel.
Is 420 Stainless Steel Food Safe?
Yes, 420 stainless steel is considered food-safe. Its good corrosion resistance and hardness make it suitable for food processing equipment, cutlery, and other applications in contact with food.
Summary & Furthermore
This article briefly explains the definition, composition, applications, and other important aspects of 402 stainless steel. To learn more about stainless steel or other steel types, check out our blog or contact our metal experts.
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