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EN 1.4550 (X6CrNiNb18-10) Stainless Steel

EN 1.4550 stainless steel is an austenitic stainless steel formulated for primary forming into wrought products. Cited properties are appropriate for the solution annealed (AT) condition. 1.4550 is the EN numeric designation for this material. X6CrNiNb18-10 is the EN chemical designation.

This material is well established: the Further Reading section below cites a number of published standards, and that list is not necessarily exhaustive.

The graph bars on the material properties cards below compare EN 1.4550 stainless steel to: wrought austenitic stainless steels (top), all iron alloys (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.

Mechanical Properties

Brinell Hardness

200

Elastic (Young's, Tensile) Modulus

200 GPa 29 x 106 psi

Elongation at Break

42 %

Fatigue Strength

210 MPa 30 x 103 psi

Impact Strength: V-Notched Charpy

90 J 67 ft-lb

Poisson's Ratio

0.28

Shear Modulus

77 GPa 11 x 106 psi

Shear Strength

430 MPa 62 x 103 psi

Tensile Strength: Ultimate (UTS)

620 MPa 90 x 103 psi

Tensile Strength: Yield (Proof)

230 MPa 34 x 103 psi

Thermal Properties

Latent Heat of Fusion

290 J/g

Maximum Temperature: Corrosion

480 °C 900 °F

Maximum Temperature: Mechanical

940 °C 1720 °F

Melting Completion (Liquidus)

1430 °C 2610 °F

Melting Onset (Solidus)

1390 °C 2530 °F

Specific Heat Capacity

480 J/kg-K 0.11 BTU/lb-°F

Thermal Conductivity

15 W/m-K 8.7 BTU/h-ft-°F

Thermal Expansion

16 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

2.4 % IACS

Electrical Conductivity: Equal Weight (Specific)

2.7 % IACS

Otherwise Unclassified Properties

Base Metal Price

18 % relative

Density

7.8 g/cm3 490 lb/ft3

Embodied Carbon

3.6 kg CO2/kg material

Embodied Energy

51 MJ/kg 22 x 103 BTU/lb

Embodied Water

140 L/kg 17 gal/lb

Common Calculations

PREN (Pitting Resistance)

18

Resilience: Ultimate (Unit Rupture Work)

210 MJ/m3

Resilience: Unit (Modulus of Resilience)

140 kJ/m3

Stiffness to Weight: Axial

14 points

Stiffness to Weight: Bending

25 points

Strength to Weight: Axial

22 points

Strength to Weight: Bending

21 points

Thermal Diffusivity

4.0 mm2/s

Thermal Shock Resistance

14 points

Alloy Composition

Among wrought stainless steels, the composition of EN 1.4550 stainless steel is notable for including niobium (Nb). Niobium is primarily used to improve yield strength, particularly at elevated temperatures.

Iron (Fe)Fe 64.9 to 74
Chromium (Cr)Cr 17 to 19
Nickel (Ni)Ni 9.0 to 12
Manganese (Mn)Mn 0 to 2.0
Silicon (Si)Si 0 to 1.0
Niobium (Nb)Nb 0 to 1.0
Carbon (C)C 0 to 0.080
Phosphorus (P)P 0 to 0.045
Sulfur (S)S 0 to 0.015

All values are % weight. Ranges represent what is permitted under applicable standards.

Followup Questions

Similar Alloys

Further Reading

EN 10222-5: Steel forgings for pressure purposes - Part 5: Martensitic, austenitic and austenitic-ferritic stainless steels

EN 10272: Stainless steel bars for pressure purposes

EN 10250-4: Open die steel forgings for general engineering purposes - Part 4: Stainless steels

EN 10088-2: Stainless steels - Part 2: Technical delivery conditions for sheet/plate and strip of corrosion resisting steels for general purposes

EN 10088-3: Stainless steels - Part 3: Technical delivery conditions for semi-finished products, bars, rods, wire, sections and bright products of corrosion resisting steels for general purposes

EN 10088-1: Stainless steels - Part 1: List of stainless steels

Corrosion of Austenitic Stainless Steels: Mechanism, Mitigation and Monitoring, H. S. Khatak and B. Raj (editors), 2002

Austenitic Stainless Steels: Microstructure and Mechanical Properties, P. Marshall, 1984

Advances in Stainless Steels, Baldev Raj et al. (editors), 2010