420 Stainless Steel - 1.4034 - X46Cr13 - 51420 - ~SUS 420J1

Where can 420 stainless steel be used?

Due to the combination of high hardness, corrosion and wear resistance and polishability the 420 stainless steel can be used for applications like razor blades, dental and surgical instruments, plastic molds, and machine, valve and firearm parts.

Is the 420 a stainless steel?

Yes, the 420 is a martensitic stainless steel with a chromium content of approx. 12,5 to 14,5% of chromium which offers the corrosion resistance that makes it stainless.

420 stainless steel corrosion resistance

420 stainless steel / general corrosion

420 stainless steel has a good resistance to water and steam, and a moderate resistance to corrosive environments free of chlorides. 420 is not resistant to intergranular corrosion after being welded or in its annealed condition. Where corrosion resistance is an issue, care should be taken not to over temper the material or to use it in its annealed condition, but to use it in the hardened condition with a high finished, smooth surface. 

Is the 420 stainless steel magnetizable?

As a martensitic stainless steel the 420 has a crystal structure that is ferromagnetic, this makes the 420 magnetizable in its annealed and hardened condition. The 420 steel is suitable for magnetic clamping.

420 stainless steel heat resistance

420 should be used at moderately elevated temperatures, it is not recommended to use it for high temperatures above 800°F (427°C) as it reduces the corrosion resistance and mechanical properties.

420 stainless steel heat treatment

Annealing stainless steel 420

To anneal 420 stainless, hold the material at a temperature range of 1382-1562°F (750-850°C) and cool slowly in the furnace or in air.

420 stainless steel stress relieving

Heat the workpiece to a temperature of 300-800°F (149-427°C) and hold for 1-3 hours, then cool in air or quench in oil or water.

Hardening 420 stainless steel

Heat the steel uniformly to a temperature range of 1742 - 1922°F (950 - 1050°C) and follow this up with a rapid cooling in air or oil.

420 stainless steel quenching

During quenching the 420 stainless steel undergoes the phase transformation from austenite to martensite. Quick cooling can achieve a higher hardness, the quicker the material is cooled down the more martensite form whereas a slow cooling of this material may leave some austenite or other phases behind. Rapid cooling though has its risks too, it may introduce stresses that can lead to quench cracking and may cost the parts its toughness. 

Tempering stainless steel 420

To reach a variety of hardness values and mechanical properties, heat the work piece to 300 - 1292°F (150 - 700°C) and cool in still air. For optimal corrosion resistance and mechanical properties, the temperature range of 797-1112°F (425-600°C) should be avoided.

Tempering this steel grade at low temperatures will achieve a higher hardness, while higher temperatures improve the toughness but will decrease the hardness.

Reduced impact toughness might be the result of temper embrittlement which might occur when tempering in a range of 800 - 1100°F (425 - 595°C).

Dimensional changes of the 420 stainless steel

While transforming from austenite to martensite there can be a slight shrinkage which might have an impact on the dimensions of the parts and retained austenite might further impact dimensions during tempering.

Electrical Discharge Machining (EDM) the 420 stainless steel

EDM can be used to achieve various surface finishes but is mainly used to produce intricate shapes, small details and complex geometries in hard material. As the 420 is at the higher end of hardness EDM can be used successfully. Care with electrodes, dielectric fluid and cutting speeds should be taken with finish and applications in mind. 

420 stainless steel surface treatment

When contemplating a surface treatment the finish and intended application should be taken in consideration. Some surface finishes can impact properties needed, if corrosion resistance is a needed property, a surface treatment that enhances the natural corrosion resistance should be chosen.

Below are some examples for possible surface treatments.

420 stainless steel passivation

Passivation increases corrosion resistance by treating the surface with an acid solution to remove free iron from the surface.

Polishing 420 stainless steel

Polishing the surface to a mirror finish can improve its own corrosion resistance as a smooth finish can minimize adhesion of contaminants.

Electropolishing the stainless steel 420

As a non-mechanical chemical process using an electric current to remove a thin layer of material will give the 420 a smooth and shiny surface. It can minimize bacterial adhesion which can be an advantage for medical tools and /or food processing equipment.

Nitriding 420 stainless steel

As well as the surface treatments before, nitriding can enhance the natural corrosion resistance by introducing nitrogen into the surface. This process can also improve its wear resistance.

Shot peening / shot blasting 420 stainless steel

This process is an impact treatment where multiple high velocity shots are blasted onto the material surface leaving small indentations removing stress risers. It makes the surface more resistant and can prevent fatigue and stress corrosion failure.

Note: Protective gear like goggles, masks, helmets, gloves and protective clothing should be worn and adequate ventilation or dust extraction should be provided.

Appropriate guards to prevent shot spillage should be in place, equipment regularly maintained and shot should be free from contaminants.

Bead blasting / abrasive blasting the 420 stainless steel

Abrasive particles like glass or ceramic beads are blasted against the surface to remove contaminants like rust, paint or scale and to promote a uniform matt finish.

Note: Care has to be taken during this process as the process produces dust and small parts might be propelled back. Protective gear like masks, helmets and protective clothing should be worn and adequate ventilation or dust extraction should be provided.

Black oxide (bluing) stainless steel 420

This is a superficial treatment that may enhance corrosion resistance but is most often used to color the surface blue-black to reduce the reflection of light.

PVD and CVD deposit 420 stainless steel

Physical Vapor Deposition (PVD) and Chemical Vapor Deposition (CVD) deposit a thin layer over the material surface to give it additional protection, enhance wear resistance and lubricity. 

420 stainless steels machinability

420 stainless steel machines similar to some high carbon steels and creates tough stringy chips.

Annealed the material is, to some extent, easier to machine than in its hardened condition. 

Forging 420 stainless steel

Slowly heat the workpiece to a temperature of about 1472°F (800°C), then more rapidly to 1922-2084°F (1050-1140°C). Forging should be done in the temperature range of 2012-1472°F (1100-800°C), then slowly cool in the furnace, dry ash or materials that will promote slow cooling.

While forging has its advantages, like grain refinement, elimination of porosity, better directional strength and an improved microstructure to name just a few, it has some disadvantages as well. Forging can, especially in its hardened condition, be hard on tool wear, form an oxide scale that needs to be removed after forging, and may require a heat treatment after forging. Forging is reduced to the more rough shapes compared to casting, machining or EDM.

Welding stainless steel 420

As an air-hardening steel the 420 stainless steel is rarely welded.

If welding cannot be avoided, preheat to 300-400°F (149-204°C) before welding, then anneal 6-8 hours at a temperature of 1350-1450°F (732-788°C) followed by air cooling. To retain its mechanical properties, if fillers are required, the filler should be similar to the base material.

420 stainless steel wear resistance

On a scale where 1 is low and 6 is high the 420 stainless steel comes in at 4.

420 stainless steel tensile strength

The tensile strength for the 420 is approx. 118.2 KSI (0.145KSI = 1MPa). This value is the result from a tensile test to show how much force is needed before the material starts to stretch or elongate before it breaks.

420 stainless steel yield strength

The yield strength shows how much stress can be applied to a material before it plastically deforms. Beyond this point it does not return to its original form when the stresses have been removed.The material deforms permanently or breaks past that point. 

The range for the stainless steel 420 is between 74.4 to 200 KSI (512.9 - 1378.9 MPa).

AISI 420 stainless steel working hardness

The working hardness for the AISI 420 stainless steel is in a range of 469 - 552 BHN (50 - 55 HRC). 

420 stainless steel specific heat capacity

The specific heat capacity of the 420 stainless steel at room temperature is at 0.46 J/g-°C (0.109 BTU/lb-°F). This value shows how much heat is needed  to heat 1lb of material by 1 Fahrenheit.

420 stainless steel continuous TTT-diagram

This diagram shows the micro changes at different temperatures which are important during heat treatment. They show the optimum condition for the hardening, annealing and normalizing process.

420 stainless steel isothermal TTT-diagram

This diagram shows the structural changes at micro level over time at a constant temperature. It shows at what temperature and after what time different phases, e.g., perlite, martensite or bainite start to build.

420 stainless steel steel properties

420 stainless steel steel density

Typically the density of 420 stainless steel is 0.278 lb/in3 (7.7g/cm3) at room temperature.

420 stainless steel thermal conductivity

The heat conductivity for the 420 stainless steel is at 30 W/(m*K) (208 BTU/(h-ft*°F)) at room temperature.

Thermal expansion coefficient for the 420 stainless steel

The thermal expansion coefficient shows how much the 420 might expand or contract when the temperature is changed. This is very important information, especially when working with high temperatures, or where there are strong temperature changes during applications. 

420 stainless steel specific electrical resistivity

You can find the temperature dependent material constant (Resistivity) in the following table. The electrical conductivity is the reciprocal value of the specific resistance.

420 stainless steel Modulus of elasticity (Young’s Modulus)

The relationship between stress and strain of steel is described in the modulus of elasticity (Young’s Modulus) and can be found in the table below with the according values and temperatures.

Is the 420 stainless steel a knife steel?

The 420 can be used as a knife steel. It is easily sharpened, has good corrosion resistance, and good toughness. One drawback is its edge retention which means it needs to be sharpened more often.

Conclusion

Keeping applications and properties in mind, the 420 stainless steel achieves a good hardness, strength, and wear resistance when hardened, it has a good corrosion resistance though on the lower end in comparison to other stainless steels. This does not only make it a good choice for knives but also cutting instruments, tools and decorative applications.

420 stainless steel datasheet

As a 420 steel supplier we provide you with the datasheet for the 420 steel in PDF format.

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