Acidur 4418 QT900 Bar

Alternative and trade names
Acidur 4418


1.4418 (X4CrNiMo16-5-1) Quenched and Tempered steel that shows very good corrosion resistance in aggressive media coupled with very good mechanical and impact properties.

Related Standards

Equivalent Materials



Density ρ

7.7 g/cm³ at 20 °C


Diameter d

250 mm



Charpy impact energy, V-notch aK,charpy,V-notch

80 J at 20 °C

Elastic modulus E

200 GPa at 20 °C

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Elongation A5 A5

16 % at 20 °C

Elongation A5, transverse A5,trans

14 % at 20 °C

Hardness, Brinell HB

320 [-] at 20 °C


Tensile strength Rm

900 - 1100 MPa at 20 °C

Yield strength Rp0.2 Rp0.2

700 MPa at 20 °C

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Coefficient of thermal expansion α

1.08E-5 1/K at 100 °C

for 20°C to the mentioned temperature

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Specific heat capacity cp

430 J/(kg·K) at 20 °C

Thermal conductivity λ

15 W/(m·K) at 20 °C


Electrical resistivity ρel

7E-7 Ω·m at 20 °C

Chemical properties


Weight %






15 - 17 %


4 - 6 %


1.5 %


0.8 - 1.5 %


Technological properties

Application areas

Chemical industry, Ship Building, Mechanical Engineering, Aviation and Aerospace industry

Corrosion properties

Good - Due to its higher alloy content, 1.4418 is more resistant to corrosion than 1.4057 and the addition of molybdenum allows limited exposure to marine environments. As a result of its chemical composition and microstructure, 1.4418 is extremely resistant to intergranular corrosion, corrosion fatigue and stress corrosion cracking. PRE = 17.95 – 22.27

General machinability

Poor - The machinability of this grade of stainless steel is directly related to its hardness. 1.4418 machines similar to carbon steels of the same hardness. Although it must be realised that the machining parameters will vary depending on the heat treated condition and hardness of the steel.

Heat Treatment

1.4418 can be soft annealed by holding at a temperature of approximately 600 °C (but not in excess of 625 °C), followed by slow cooling in air. 1.4418 can be hardened by holding at a temperature between 1000 °C – 1050 °C followed by cooling in air, oil or polymer. Tempering 550-620°C in water, air

Hot forming

It is formable at 900-1150°C

Processing history

Quenched and tempered QT 900


Good - 1.4418 is readily weldable using all standard welding techniques. Care must however be taken to ensure that hydrogen or carbon containing gasses are not used when welding under shielded gas. Pre-heating of the work piece to a temperature between 100 °C and 200 °C is recommended. After welding, the weldment should either be annealed or tempered, as described before. If a filler material is required, then either a matching filler or Novonit® 4430 should be used.

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.