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
0.28
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
Density
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)
13
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.
| Fe | 71.5 to 79.2 | |
| Cr | 11 to 12.5 | |
| Ni | 7.5 to 9.5 | |
| Cu | 1.5 to 2.5 | |
| Ti | 0.8 to 1.4 | |
| Mn | 0 to 0.5 | |
| Si | 0 to 0.5 | |
| Mo | 0 to 0.5 | |
| Nb | 0 to 0.5 | |
| Ta | 0 to 0.5 | |
| C | 0 to 0.050 | |
| P | 0 to 0.040 | |
| 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