1.4057, DIN X17CrNi16-2, AISI 431

1.4057, DIN X17CrNi16-2, AISI 431

Designation by Standards

 

Chemical Composition (in weight %)

Description
431 is a martensitic stainless combining excellent impact strength at high hardness levels with the best corrosion resistance of any martensitic stainless steels. Steel with high polishability. For application up to working temperature 500^oC.

Applications
431 has been successfully used in a variety of aircraft and general industrial applications. These include fasteners, shafts, bolts, valve components and chemical equipment, components for dairies, machine building and paper industry.

Physical properties (avarage values) at ambient temperature
Modulus of elasticity [10³ x N/mm²]: 216
Density [g/cm³]: 7.70
Thermal conductivity [W/m.K]: 25.0
Electric resistivity [Ohm mm²/m]: 0.70
Specific heat capacity[J/g.K]: 0.46

Modulus of Elasticity [10³ N/mm²]

Coefficient of Linear Thermal Expansion 10^{-6 o}C^-1

Soft Annealing
Heat to 660-750^oC, cool slowly in furnace. This will produce a maximum Brinell hardness of 295.

Hardening
Harden from a temperature of 980-1030^oC followed by oil or air quenching. Hardness after quenching is about 47 HRC.

Tempering
Tempering temperature: For Q+T 800: 750-800^oC. For Q+T 900: 600-650^oC.

0.2 % Proof Stress (N/mm²) at Elevated Temperatures

Forging
Hot forming temperature: 1100-800^oC, slow cooling.

Machinability
In the fully annealed condition, 431 will gall and build up on the tools. Good surface finishes are not easily obtained.

Corrosion Resistance
431 is superior to all other martensitic grades in terms of corrosion resistance. Will resist dilute acids and alkalis, neutral and basic salts, food acids, fresh water and atmosphere.

Welding
Most electric welding procedures have proven successful with 431 stainless. Filler metal should be AWS E/ER410.To avoid cracking, pre-heat the workpiece to 204-316^oC. After air cooling, treat at 649^oC to reattain maximum properties.

Embittlemnt: It must be in mind that the temperature range between 425 and 525^oC must be avoided owing to embritllement at 475^oC.

Cold working
This alloy is easily drawn, spun, headed, sheared and bent compared with other stainless steels.