SUS431 Stainless Steel

in stock


We are the SUS 431 / SS 431 / 431 Stainless Steel Supplier Malaysia.

With the strong global sourcing in Duplex Stainless Steel, our sales and supplier network including : Australia, Pakistan,  Malaysia, Singapore, Taiwan, China, Vietnam, Belgium, Japan, South Korea, Philippines, France, United Kingdom, Indonesia, Thailand, Hong Kong, China, Sweden, United States, Dubai, Finland, Brunei, Germany.


Leading Supplier of Stainless Steel 431

Specifications of Type 431 Stainless Steel also equivalent to 
  • Grade 431 | UNS S43100 | SUS431 


Properties of SUS431 Stainless Steel

This heat treatable martensitic, nickel-bearing grade has the best corrosion resistance properties of all the martensitic grades.

It has excellent tensile and torque strength, and good toughness, making it ideally suited to shafting and bolt applications. It can be hardened to approximately 40HRC. Because of its high yield strength, this grade is not readily cold worked and is therefore not recommended for use in operations such as cold heading, bending, deep drawing or spinning.

Martensitic stainless steels are optimised for high hardness, and other properties are to some degree compromised.

Fabrication must be by methods that allow for poor weldability and usually also allow for a final harden and temper heat treatment.

Corrosion resistance is lower than the common austenitic grades, and their useful operating temperature range is limited by their loss of ductility at sub-zero temperatures and loss of strength by over-tempering at elevated temperatures.


Key Properties 

These properties are specified for bar product in ASTM A276. Similar but not necessarily identical properties are specified for other products such as plate and forgings in their respective specifications.


Physical Properties for SUS431 

Typical Mechanical Properties for Grade 431 Stainless Steels as below

GradeDensity (kg/m3)Elastic Modulus (GPa)Mean Coefficient of Thermal Expansion (mm/m/°C)Thermal Conductivity (W/m.K)Specific Heat
0-100°C (J/kg.K)
Electrical Resistivity (nW.m)
0-100°0-315°0-538°Cat 100°Cat 500°C


Mechanical Properties 

Tempering Temperature (°C)Tensile Strength (MPa)Yield Strength 0.2% Proof (MPa)Elongation (% in 50mm)Hardness Brinell (HB)Impact Charpy V (J)
Annealed *86265520285 max-

* Stainless Steel Type 431 is frequently stocked and supplied in “Condition T”, with specified tensile strength of 850 – 1000MPa.

*  Annealed tensile properties are typical for Condition A of ASTM A276; annealed hardness is the specified maximum. Grade 431 is only rarely stocked in annealed Condition A.# Due to associated low impact resistance this steel should not be tempered in the range 425-600°C


Corrosion Resistance 

Excellent resistance to a wide variety of corrosive media. Reasonable resistance to salt water in cold southern waters but less resistant than Grade 316 in tropical waters. Overall the corrosion resistance of 431 is approximately the same as or slightly below that of Stainless Steel grade 304 (SUS304).

Performance is best with a smooth surface finish, in the hardened and tempered condition.


Heat Resistance 

Resists scaling in intermittent service to 925°C and in continuous service to 870°C, but is generally not recommended for use in temperatures above the relevant tempering temperature, because of reduction in mechanical properties.


Heat Treatment 

Full anneal – not practical for this grade – it hardens even when cooled slowly.

Process Anneal – heat to 620-660°C and air cool.

Hardened by heating to 980-1065°C, holding for about 1/2 hour then quenching in air or oil. Pre-heating at 760-790°C may be useful for complex parts or those already hardened. Temper to suit mechanical requirements, at temperatures as indicated in the accompanying table.

The tempering range 425-600°C should be avoided due to reduced impact toughness, although the effect is less marked than in most other martensitic grades.


Welding –Welding is difficult due to cracking. A pre-heat of 200-300°C is recommended prior to welding. Grade 410 filler rod can be used, but Grades 308L, 309 or 310 will provide more ductile welds, so long as matching properties are not required. Post-weld heat treat at 650°C.


Machining –In the annealed condition this grade is relatively easily machined, but if hardened to above 30HRC machining becomes more difficult.


Comparison of SUS431 Stainless Steel 

GradeUNS NoOld BritishEuronorm Swedish SSJapanese JIS
SUS431S43100431S29571.4057X17CrNi16-22321SUS 431

* These comparisons are approximate only. The list is intended as a comparison of functionally similar materials not as a schedule of contractual equivalents. If exact equivalents are needed original specifications must be consulted.


Possible Alternative Grades to Grade 430 Stainless Steel

GradeWhy it might be chosen instead of 431
SUS410nly a lower hardened strength is needed.
SUS416 High machinability is required, and the lower hardened strength and lower corrosion resistance of 416 is acceptable.
SUS440CA higher hardened strength or hardness than can be obtained from 420 is needed.

Technical Applications for SUS431 

SUS431 Stainless Steel can be used in the following applications : 

  • Nuts and bolts
  • Propeller shafting
  • Pump shafts
  • Beater bars
  • Marine hardware
  • Laboratory benches & equipment
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