420 Stainless Steel | 1.2083 | 2Cr13
AOBO STEEL - Trusted Global Tool Steel Supplier
420 stainless steel is a martensitic stainless steel, which is a type of iron-chromium alloy. It is part of the 400-series stainless steel classifications. Unlike some other stainless steel types, AISI 420 stainless steel is magnetic.
1. Applications
- Cutlery and Sharp-edged Tools
- Medical and Surgical Instruments
- Plastic Molds and Mold Tools
- Valve and Pump Parts
- Gears, Shafts, and Rollers
- Industrial and Wear-Resistant Applications
- Cups and Other Formed Parts
- Bearings
- Other Applications: Springs, Hand Tools, Magnets, Fasteners, Machinery Parts, Press Plates, Automotive exhaust components, Dies for fine piercing of micropatterns into metallic sheets, Domestic appliances and utensils.
2. 420 Stainless Steel Composition
Element | Carbon (C) | Manganese (Mn) | Silicon (Si) | Phosphorus (P) | Sulfur (S) | Chromium (Cr) |
Compositional | ≤ 0.15% | ≤ 1.00% | ≤ 0.50% | ≤ 0.040% | ≤ 0.030% | 12.00 – 14.00% |
【Reference: Bringas, J. E. (Ed.). (2004). Handbook of Comparative World Steel Standards (3rd ed., p. 434). ASTM International.】
3. 420 Stainless Steel Properties
- Hardness and Wear Resistance: After appropriate heat treatment, 420 stainless steel hardness is 46–52 HRC. This hardness gives it good wear and corrosion resistance.
- Corrosion Resistance: The chromium in AISI 420 stainless steel forms a passivation layer that protects its surface and provides excellent corrosion resistance in mild atmospheric, domestic, and industrial environments.
- Polishability: This grade exhibits excellent polishability, making it a preferred choice for applications requiring a high-quality surface finish, such as plastic injection molds and optical components.
- Toughness and Weldability: The carbon content is higher than that of low-carbon steel, making it harder than low-carbon steel but with lower toughness. Due to its high carbon content, it also has poor weldability. If welding is necessary, significant preheating and post-weld heat treatments (like annealing) are often required to prevent cracking. Using specialized filler metals (e.g., ERNiCr-3) might be considered, though this can affect the final strength and hardness of the weld area.
- Machinability: In its annealed condition, 420 steel offers fair machinability. For applications demanding more complex machining, a free-machining variant, 420F (with added sulfur), is available. Note that the sulfur addition can slightly decrease notch toughness.

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4. Heat Treatment
Martensitic stainless steels, including 420 stainless steel, are hardened by heating them above their transformation temperature to achieve a fully austenitic structure, followed by rapid cooling in oil or air. It has a low thermal conductivity, which can lead to uneven heating during rapid heating or quenching, resulting in distortion, warping, or cracking. Therefore, we strongly recommend preheating.
The heat treatment involves austenitizing, quenching, and then tempering to optimize its mechanical properties, particularly ductility and toughness.
4.1 Hardening(Austenitizing)
The hardening temperature for 420 steel is 975 °C to 1075 °C (1787 °F to 1967 °F), though some sources list it as 954 °C to 1010 °C (1750 °F to 1850 °F). However, based on our experience, the former range is more appropriate.
Soak time is typically about 30 minutes per inch (1.2 minutes per millimeter) of thickness at the hardening temperature.
To prevent decarburization, 420 stainless steel should be hardened in a controlled neutral atmosphere, vacuum, or neutral-salt furnace environment.
4.2 Quenching
For complex or irregularly shaped workpieces, we suggest air quenching to minimize deformation and reduce the risk of cracking. If a higher hardness is required, we opt for oil quenching. The quenching process involves cooling the material to 66 °C (150 °F) when air-quenched, or to 66-93 °C (150-200 °F) when oil-quenched. Please note that the tempering treatment should be performed immediately after quenching.
4.3 Tempering
Tempering can improve the toughness and strength of 420 and adjust its hardness. 420 steel material must undergo at least two tempering cycles, or even three. For most applications, the minimum tempering temperature is 204°C (400°F). The soaking time is 2 hours per inch (4.7 minutes per millimeter) of thickness at the specified temperature. Between each tempering cycle, the parts should be allowed to cool naturally to room temperature.
Effect of Tempering Temperature on Properties:
- Hardness after different tempering temperatures: Hardness of 420 stainless steel is: 52 HRC minimum at 149 °C (300 °F), 50 HRC minimum at 204 °C (400 °F), and 48 HRC minimum at 316 °C (600 °F).
- Temper Embrittlement and Corrosion Resistance: 420 steel has the characteristic of temper embrittlement. Do NOT temper at temperatures ABOVE 427°C (800°F), as this temperature range may result in a significant decrease in impact strength and corrosion resistance. This reduction is attributed to the precipitation of coarser chromium carbides (Cr23C6), which can create chromium-depleted regions around the carbides. This negative effect disappears when the tempering temperature is 593 °C (1100 °F) or higher. At temperatures above 600 °C, chromium diffusion is thought to “heal” these depleted zones, restoring corrosion resistance. Within this temperature range, the toughness of 420 increases, but its hardness decreases.
4.4 Stress Relieving (Unhardened Material)
For unhardened 420 stainless steel parts, stress relieving can be performed by heating slowly to 677 °C (1250 °F) and soaking for 2 hours per inch of thickness, followed by a slow cool in the furnace to room temperature.
[Reference: Leed, R. M. (2007). Tool and die making troubleshooter. Society of Manufacturing Engineers.]
5. Equivalent Grades
- JIS (Japan):SUS420J1, SUS420J2
- DIN (Germany):4021, 1.4028, 1.2083 (X42Cr13 – often used for molds)
- GB(China): 2Cr13
6. Compare 420 stainless steel with other steels
6.1 420 stainless steel vs. 304
420 steel is a hard, strong, wear-resistant, and magnetic martensitic alloy, best suited for applications requiring high performance after heat treatment. However, it requires careful handling during welding and tempering for optimal corrosion resistance. 304 steel, on the other hand, is a ductile, formable, generally non-magnetic austenitic alloy prized for its versatile corrosion resistance, excellent weldability, and suitability for a broad range of general and high-temperature applications.
Feature | 420 | 304 |
Classification | Martensitic | Austenitic |
Magnetic? | Yes (Ferromagnetic) | Typically No (Non-magnetic in annealed condition) |
Hardenable? | Yes, by heat treatment (quench and temper) | No, hardens by cold work |
Carbon Content | Higher (0.15% min, often 0.2-0.4%) | Lower (max 0.08%) |
Nickel Content | Very low or absent | Significant (8-12%) |
Max Hardness | Much higher (e.g., C-54 to C-60 after heat treat) | Lower (max B-92 annealed) |
Corrosion | Moderate, dependent on heat treatment; lower than 304 | Good, “best all-rounder”; higher than 420 |
Weldability | Difficult to weld | Excellent weldability (especially 304L) |
Toughness | Lower impact strength, susceptible to temper brittleness | High ductility and toughness |
Typical Uses | Cutlery, surgical instruments, molds, shafts, valves | Food processing, appliances, automotive exhaust, general purpose |
6.2 420 stainless steel vs. 316
420 steel is a hardenable martensitic stainless steel with high strength, hardness, and wear resistance, but it has moderate corrosion resistance and is sensitive to heat treatment. In contrast, 316 steel is a non-hardenable austenitic stainless steel with excellent corrosion resistance, particularly in chloride environments, where it exhibits outstanding resistance to pitting and crevice corrosion.
Feature | 420 | 316 |
Classification | Martensitic | Austenitic |
Hardenability | Can be hardened by heat treatment to over 50 HRC. | Cannot be hardened by heat treatment; can be hardened by cold working. |
Hardness | Annealed: B-92 Rockwell. Heat-treated: C-54 Rockwell. | Annealed: B-80 Rockwell (up to B-90). |
Tensile Strength | Annealed: 95 ksi. Heat-treated: up to 250 ksi. | Annealed: 75 ksi (316), 70 ksi (316L). |
Yield Strength | Annealed: 50 ksi. Heat-treated: up to 200 ksi. | Annealed: 30 ksi (316), 25 ksi (316L). |
Ductility | Good toughness, but ductility decreases as hardness increases. | Excellent ductility and high elongation, even at low temperatures. |
Corrosion Resistance | Good, but generally lower than austenitic grades. Tempering can reduce resistance. | Excellent, especially against pitting and crevice corrosion due to molybdenum. |
Weldability | Difficult to weld; not recommended for welded applications. | Good weldability, especially the ‘L’ grade (316L). |
Magnetic Properties | Ferromagnetic. | Generally non-magnetic (can be slightly magnetic after cold work). |
Common Applications | Cutlery, surgical instruments, molds, shafts, valve parts. | Chemical processing, marine applications, architectural cladding, medical implants. |
FAQs
1. Is 420 good steel for a knife?
420 steel presents a viable option for knife manufacturing, offering a good balance of corrosion resistance, abrasion resistance, hardness, and machinability.
2. Which is better 440 or 420 steel?
If the primary requirement for your factory’s knives is superior edge retention and wear resistance, the 440 series, particularly 440C with its higher carbon content, would generally be considered better than 420 steel. However, this may come with a slight reduction in stain resistance compared to lower carbon 440 variants, such as 440A. On the other hand, 420 steel offers a good balance of corrosion resistance, reasonable hardness for many general-purpose applications, and better machinability in the annealed state.
3. Is 420 a good stainless steel?
420 steel is indeed a good stainless steel, offering a satisfactory level of corrosion resistance for a wide range of applications, particularly when properly heat-treated. Its combination of corrosion resistance with achievable high hardness and wear resistance makes it a versatile material, notably for cutlery and certain tooling applications. However, for exceptionally aggressive corrosive environments, exploring higher-alloyed stainless steel grades might be a prudent consideration for your factory. Defining the specific service conditions and performance requirements of your knife products will be crucial in making the most optimal material selection.
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