431 Stainless Steel - 1.4057 - X17CrNi16-2 - ~SUS 431

431 with added chromium and nickel alloys, giving it its better toughness as well as better corrosion resistance compared to straight up chromium stainless steels. This makes this steel grade ideal for operations like deep drawing, compressor parts and construction. This steel grade is also often used in processing chemically aggressive plastics, like PVC for instance.

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431 Stainless Steel: Standard values

Working hardness: approx. 32 HRC - 47 HRC
Delivery condition: max. 331HB

Chemical composition in %

C

0.120000

0.12

0.220000

0.22
Si

0.000000

0

1.000000

1
Mn

0.000000

0

1.500000

1.5
P

0.000000

0

0.040000

0.04
S

0.000000

0

0.030000

0.03
Cr

15.000000

15

17.000000

17
Ni

1.500000

1.5

2.500000

2.5

431 Stainless Steel: Technical Data

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431 Stainless Steel: Technical Properties

Martensitic chromium steel with high strength (tempered condition) and good corrosion resistance (added nickel). It is easy to weld and is conditionally acid resistant. The material has poor forgeability.

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431 Stainless Steel: Applications

mechanical engineering, automotive industry, oil and petrochemical industry, aviation, food industry, soap industry, acetic acid industry, shafts, pump parts, perforated plates, spindles, piston rods, valve cones, turbine blades

Chemical designation: Working hardness: approx. 32 HRC - 47 HRC
Delivery condition: max. 331HB

C

0.120000

0.12

0.220000

0.22
Si

0.000000

0

1.000000

1
Mn

0.000000

0

1.500000

1.5
P

0.000000

0

0.040000

0.04
S

0.000000

0

0.030000

0.03
Cr

15.000000

15

17.000000

17
Ni

1.500000

1.5

2.500000

2.5

Martensitic chromium steel with high strength (tempered condition) and good corrosion resistance (added nickel). It is easy to weld and is conditionally acid resistant. The material has poor forgeability.

mechanical engineering, automotive industry, oil and petrochemical industry, aviation, food industry, soap industry, acetic acid industry, shafts, pump parts, perforated plates, spindles, piston rods, valve cones, turbine blades

431 General Information

Where can stainless steel 431 be used?

Due to its tensile strength and corrosion resistance 431 can be used for fasteners like bolts and screws or mechanical components like shafts and axles. Furthermore it can be used for pumps and valve components, aircraft components like landing gear or pivot pins. Automotive parts like engine components and exhaust system parts or in the food processing industry as it can withstand harsher cleaning processes. With its sharpness and corrosion resistance the 431 lends itself for cutlery and surgical instruments. 

Is the 431 a stainless steel?

Yes, the 431 is a stainless steel as it contains a mass fraction of 15 - 17% of chromium.

Is the 431 steel corrosion resistant?

A corrosion resistant steel has a minimum of 10.5% chromium, with 15 - 17% chromium content the 431 is a classic stainless steel and is therefore corrosion resistant. 


General corrosion

The 431 offers corrosion resistance in mild atmospheric environments with exposure to moisture.

Is the 431 stainless steel magnetizable?

As a martensitic stainless steel the 431 can be magnetized and can be used for applications where this is desired or needed like magnetic clamping.

Heat resistance for the 431 stainless steel

Stainless steel 431 should not be used at temperatures above the standard tempering temperature, due to the loss of mechanical properties. With occasional operations at 1697°F (925°C) and continuous operations at a temperature of 1598°F (870°C) this steel grade is resistant to scaling.

431 stainless steel heat treatment

Desired properties dictate temperatures, holding times and cooling rates during the heat treatment of the 431 stainless steel.

431 stainless steel heat treatment scheme431 stainless steel heat treatment scheme


Annealing 431 stainless steel

Heat parts to a temperature range of 1256-1472°F (680-800°C) and hold, then cool slowly and controlled in the furnace.


Austenitizing 431 stainless steel

Heat the material to a range of 1742-1922°F (950-1050°C) and hold to make sure the whole structure has been transformed to austenite followed by cooling the material in oil or air. This steel grade tends to harden by cooling in air.


Quenching 431 stainless steel

Quenching the 431 stainless in oil, air or water quickly transforms the austenite into a hard and brittle martensitic structure. Properties are depending on which quenching medium is being used.

• Oil
• Air
• Water


Tempering stainless steel 431

To reduce the brittleness and to improve toughness, tempering is a critical step in the heat treatment process for the 431 stainless steel.

Heat the workpiece uniformly to a temperature of 1112-1202°F (600-650°C) and hold for a minimum of 1 hour and then cool in air.

431 stainless steel tempering chart diagram431 stainless steel tempering chart diagram


Dimensional changes of the 431 stainless steel

Dimensional changes happen when the material undergoes heat treatment or cooling due to phase changes during the treatment.

During austenitization, when the material is heated, it can expand. While tempering internal stresses are redistributed which might expand the material slightly but not as much as during austenitization. On the other hand, cooling the 431 by quenching, the phase change from austenite to martensite, can reduce dimensions by contracting. Excessive contraction of the material may result in warping, distortion or cracking when not controlled properly.


Electrical Discharge Machining (EDM) of 431 stainless steel

EDM can be used for the 431 stainless steel, though it should be considered in what condition, annealed or hardened, it is being EDM’d. Hardened it can be more challenging and machining parameters as well as specialized electrodes should be considered. So when choosing EDM for the 431 it should be carefully planned and controlled.  

Surface treatment of the 431 stainless steel

Nitriding 431 stainless steel

Nitriding introduces nitrogen into the surface layer which gives the 431 an improved wear resistance due to the hard nitride layer.

431 stainless steel passivation

Passivation removes free iron and contaminants from the surface of the 431. It creates a passive oxide layer which can prevent rust and other corrosion when exposed to corrosive environments. 

Physical Vapor Deposition (PVD), Chemical Vapor deposition (CVD) and Electroplating

To enhance corrosion resistance and hardness or reduce friction the 431 can be coated by PVD, CVD and Electroplating.

Shot Peening the 431 stainless steel

Shot peening an impact treatment blasts multiple high velocity shots onto a material surface leaving small indentations which replace the tensile stress on the surface with a compressive layer. It solidifies the material and makes the surface more resistant which can prevent fatigue and can optimize the form and weight of the parts.

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.

Electropolishing

To improve the aesthetic, surface finish, corrosion resistance and remove embedded contaminants from the surface the 431 can be electropolished. This treatment removes a thin surface layer in an electrochemical process.

Blackening

A chemical process which darkens the material surface for decorative purposes, blackening can also reduce light reflecting off the surface.

431 stainless steel machinability

In its annealed condition 431 is to some extent easily machined. In its hardened condition, above 277 BHN (30 HRC), it is more difficult to machine.

Forging 431 stainless steel

Carefully and slowly heat the work piece to a temperature of about 1562°F (850°C) and then rapidly increase heat to a temperature of 2102-2156°F (1150-1180°C). The forging temperature is 2156-1742°F (1180-950°C) followed by a slow cooling in the furnace, dry ash or other materials which support a slow cooling.

Welding 431 stainless steel

Preheat the parts to about 212-572°F (100-300°C), welding temperature under 392°F (200°C) should be avoided. After welding is finished and the workpiece has reached an ambient temperature, heat for a post-weld heat treatment to 1202°F (650°C). Without the additional post-weld heat treatment, the mechanical properties in the heat affected areas and in the weld seam may be very different to those in the base metal. To prevent contamination, welding with gas containing hydrogen or nitrogen should be avoided as it affects the mechanical properties negatively. In order to ensure the best possible corrosion resistance in the weld, tempering colors have to be removed either mechanically or chemically.

431 stainless steel wear resistance

On a scale of 1 to 6 where 1 is low and 6 is high the 431 scores a 3.

Tensile strength for stainless steel 431

Stainless steel 431 has a tensile strength of approx. 152.2 KSI on delivery (0.145 KSI = 1MPa). In order to reach this value, a tensile test is performed to show how much force is needed to stretch or elongate a sample before it breaks.

431 stainless steel yield strength

The yield strength shows how much stress can be applied before a material plastically deforms. Beyond that point the material will not return to its original form if the stresses are taken away but will stay deformed or even break.

The yield strength for the 431 stainless steel is 7469 KSI (515 MPa).

Working hardness of the 431 stainless steel

The working hardness for the 431 stainless steel is approx. 300 - 447 BHN (32 - 47 HRC).

431 stainless steel specific heat capacity

The specific heat capacity of the 431 stainless at room temperature is 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.

431 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.

431 stainless steel continuous ztu-diagram ttt-chart structural changes431 stainless steel continuous ztu-diagram ttt-chart structural changes

Steel Properties for the 431 stainless

431 stainless steel density

Typically the density of stainless steel 431 is 0.278 lb/in3 (7.7g/cm3) at room temperature.

431 stainless steel thermal conductivity

The heat conductivity for stainless steel 431 is at ~25 W/(m*K) (~173 BTU/(h-ft*°F)) at room temperature. 

431 stainless steel thermal expansion coefficient

The following table shows expansion or contraction at various temperatures, which may be very important for high temperature works or when working with high temperature changes.

Medium thermal expansion coefficient
10-6m/(m • K) At a temperature of
35.0 68 °F
10 68 - 212°F
10.5 68 - 392°F
10.5 68 - 572°F
10.6 68 - 752°F
11 68 - 932°F

Specific electrical resistivity for the 431 stainless steel

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

Table of the specific electrical resistivity
Value BAt a temperature of
~0.7 (Ohm*mm²)/m ~ 68°F

Modulus of elasticity (Young’s Modulus) for stainless steel 430

The stress and strain modulus or modulus of elasticity (Young’s modulus) for stainless steel is at 31183 KSI (215 GPa). 

Is 431 stainless steel a knife steel?

Stainless steel 431 can be used as a knife steel it offers good corrosion resistance though there are other stainless steels better suitable as they have a higher toughness and are easier to sharpen and hold an edge for longer.

Conclusion

As with all material choices, applications and properties should be considered when choosing a steel. The 431 offers good corrosion resistance in mild to moderate corrosive environments but is susceptible to pitting when exposed to chloride rich environments. It has high tensile strength, good machinability and can achieve mechanical properties like hardness or toughness by heat treating the material.

431 stainless steel datasheet

As a 431 steel supplier we provide you with the datasheet for the stainless steel 431 in PDF format.

Stainless Steel alternatives or equivalent

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Disclaimer

The data shown here has been compiled with the greatest diligence and is regularly updated with regard to the correctness and completeness of its content. The content is indicative only and should not be taken as a warranty of specific properties of the product described or a warranty of suitability for a particular purpose. All information presented is given in good faith and no liability will be accepted for actions taken by third parties in reliance on this information. ABRAMS Industries reserves the right to change or amend the information given here in full or parts without prior notice.