Acidur 4057 QT900

Alternative and trade names
Acidur 4057, 1.4057, Type 431, SUS 431
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1.4057 (X17CrNi16-2) is most commonly used in applications where the 12 % chromium steels do not exhibit sufficient resistance to corrosion or when the toughness of the 12 % martensitic stainless steels is not sufficient.

Related Standards

Equivalent Materials

This material data has been provided by Deutsche Edelstahlwerke Specialty Steel (DEW).

All metrics apply to room temperature unless otherwise stated. SI units used unless otherwise stated.
Equivalent standards are similar to one or more standards provided by the supplier. Some equivalent standards may be stricter whereas others may be outside the bounds of the original standard.

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Chemical properties



0.12 - 0.2 %


15 - 17 %




1 %


1.25 - 2.5 %


0.04 %


1 %


0.03 %

Technological properties

Application areas

Automotive industry, Chemical industry, Aerospace industry, Petrochemical industry, Mechanical engineering

Corrosion properties

Good - The formation of chromium carbides and the associated chromium depleted regions that form around these precipitates make this grade of steel susceptible to intergranular corrosion. Surface condition plays an important role in the corrosion resistance of this steel with polished surfaces exhibiting far superior corrosion resistance compared with rougher surfaces on the same material. PRE = 17.5 – 21.26

General machinability

Poor - The machinability of this grade of stainless steel is directly related to its hardness. 1.4057 machines similar to carbon steels of the same hardness. Although it must be realised that the machining parameters will vary depending on the structure/hardness of the stee

Heat Treatment

1.4057 can be hardened by holding at a temperature between 950 °C – 1060 °C followed by cooling in air or oil. The tempering temperature is dependent on the desired strength. Since this grade of steel is susceptible to 475 °C embrittlement, care must be taken to limit exposure to the temperature range 420 °C to 520 °C, both during fabrication and service. QT900 (tempered between 600 °C and 650 °C).

Hot forming

It is formable at 800-1100°C

Processing history

Quenched and tempered QT 900


Good - When welding 1.4057 with a matching filler, the work piece is usually heated to a temperature of between 100 °C and 300 °C prior to welding and is tempered as soon as possible after welding to restore some ductility to the weld zone. For optimal properties, the entire work piece should be re-heat treated. When the mechanical properties are not of primary concern, then Novonit® 4430 or 4370 can be used as the filler material. When these two fillers are used, pre-heating of the work piece is not required. Care must be taken to ensure that no nitrogen or carbon containing gasses are used for the shielding gas since this can adversely affect the properties of the weldment. To ensure adequate corrosion resistance of the weldment, any spatter or heat tint must be removed.