1.4057/ AISI 431

Quick Facts

EN 1.4057 / AISI 431 (UNS S43100) is a corrosion and acid resistant martensitic chromium steel with nickel additive. The formation of chromium carbides and the associated chromium-depleted areas makes this material susceptible to intergranular corrosion. The corrosion resistant properties are the better ones among the martensitic grades, optimized in hardened and tempered condition. Widely used in applications where high hardness are required together with good corrosion resistance.

Typical Applications

  • Aerospace / Aviation
  • Marine components
  • Mechanical engineering
  • Nuts and bolts
  • Petroleum and petrochemical industry
  • Pumps and shafts

Industry Specifications

  • SUS 431 / SS2321 / BS431S29 / GOST14Ch172N / WL4044
  • ASTM A276
  • German Material no.: 1.4057
  • X17CrNi16-2

Material may also be supplied against customer specifications, subject to enquiry.

Stock Range

We supply a range of flat bars and round bars, on both stock and indent basis.
Primarily manufactured in: Europe, US, India

Chemical Analysis

Chemical Composition, %

1.4057/ AISI 431


The corrosion resistant properties of AIS 431 are the better ones among the martensitic grades, although not as resistant as the austenitic grade. It can be optimized in hardened and tempered condition, followed by surface polishing. It has excellent resistant in various corrosive media. AISI 431 in hardened and tempered condition is machinable with all operations such as drilling and turning etc. Weldability of grade AISI 431 is satisfactory.

Weldability: good
Machinability: 5 (1 = poor – 10 = good)
Polishability: yes
Corrosion class: 2 (0 = poor – 5 = good)