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UNS S45500 (Alloy 455, XM-16) Stainless Steel

S45500 stainless steel is a precipitation-hardening stainless steel formulated for primary forming into wrought products. XM-16 is the ASTM designation for this material. S45500 is the UNS number. And Alloy 455 is the common industry name.

It has a moderately high embodied energy among wrought precipitation-hardening stainless steels. In addition, it can have a moderately high tensile strength and has a moderately high base cost.

The properties of S45500 stainless steel include four common variations. This page shows summary ranges across all of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare S45500 stainless steel to: wrought precipitation-hardening 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

280 to 500

Elastic (Young's, Tensile) Modulus

190 GPa 28 x 106 psi

Elongation at Break

3.4 to 11 %

Fatigue Strength

570 to 890 MPa 83 to 130 x 103 psi

Poisson's Ratio


Reduction in Area

34 to 45 %

Rockwell C Hardness

32 to 54

Shear Modulus

75 GPa 11 x 106 psi

Shear Strength

790 to 1090 MPa 110 to 160 x 103 psi

Tensile Strength: Ultimate (UTS)

1370 to 1850 MPa 200 to 270 x 103 psi

Tensile Strength: Yield (Proof)

1240 to 1700 MPa 180 to 250 x 103 psi

Thermal Properties

Latent Heat of Fusion

270 J/g

Maximum Temperature: Corrosion

620 °C 1140 °F

Maximum Temperature: Mechanical

760 °C 1400 °F

Melting Completion (Liquidus)

1440 °C 2630 °F

Melting Onset (Solidus)

1400 °C 2550 °F

Specific Heat Capacity

470 J/kg-K 0.11 BTU/lb-°F

Thermal Expansion

11 µm/m-K

Otherwise Unclassified Properties

Base Metal Price

17 % relative


7.9 g/cm3 490 lb/ft3

Embodied Carbon

3.8 kg CO2/kg material

Embodied Energy

57 MJ/kg 24 x 103 BTU/lb

Embodied Water

120 L/kg 14 gal/lb

Common Calculations

PREN (Pitting Resistance)


Resilience: Ultimate (Unit Rupture Work)

45 to 190 MJ/m3

Stiffness to Weight: Axial

14 points

Stiffness to Weight: Bending

24 points

Strength to Weight: Axial

48 to 65 points

Strength to Weight: Bending

35 to 42 points

Thermal Shock Resistance

48 to 64 points

Alloy Composition

Among wrought stainless steels, the composition of S45500 stainless steel is notable for including tantalum (Ta) and titanium (Ti). Tantalum is used to improve pitting corrosion resistance. Titanium is used to broadly improve mechanical properties.

Iron (Fe)Fe 71.5 to 79.2
Chromium (Cr)Cr 11 to 12.5
Nickel (Ni)Ni 7.5 to 9.5
Copper (Cu)Cu 1.5 to 2.5
Titanium (Ti)Ti 0.8 to 1.4
Manganese (Mn)Mn 0 to 0.5
Silicon (Si)Si 0 to 0.5
Molybdenum (Mo)Mo 0 to 0.5
Niobium (Nb)Nb 0 to 0.5
Tantalum (Ta)Ta 0 to 0.5
Carbon (C)C 0 to 0.050
Phosphorus (P)P 0 to 0.040
Sulfur (S)S 0 to 0.030

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

Followup Questions

Similar Alloys

Further Reading

ASTM A693: Standard Specification for Precipitation-Hardening Stainless and Heat-Resisting Steel Plate, Sheet, and Strip

ASTM A564: Standard Specification for Hot-Rolled and Cold-Finished Age-Hardening Stainless Steel Bars and Shapes

Welding Metallurgy of Stainless Steels, Erich Folkhard et al., 2012

ASTM A959: Standard Guide for Specifying Harmonized Standard Grade Compositions for Wrought Stainless Steels

Properties and Selection: Irons, Steels and High Performance Alloys, ASM Handbook vol. 1, ASM International, 1993

Corrosion of Stainless Steels, A. John Sedriks, 1996

ASM Specialty Handbook: Stainless Steels, J. R. Davis (editor), 1994

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