ASTM A369 Grade FP9 Cr-Mo Steel
ASTM A369 grade FP9 is an alloy steel formulated for primary forming into wrought products. Cited properties are appropriate for the annealed condition.
It has a fairly low thermal conductivity among wrought alloy steels in the same category. In addition, it has a fairly low tensile strength and a fairly high electrical conductivity.
The graph bars on the material properties cards below compare ASTM A369 grade FP9 to: wrought alloy steels in the same category (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
140
Elastic (Young's, Tensile) Modulus
190 GPa 28 x 106 psi
Elongation at Break
20 %
Fatigue Strength
160 MPa 24 x 103 psi
Poisson's Ratio
0.28
Shear Modulus
75 GPa 11 x 106 psi
Shear Strength
300 MPa 43 x 103 psi
Tensile Strength: Ultimate (UTS)
470 MPa 69 x 103 psi
Tensile Strength: Yield (Proof)
240 MPa 34 x 103 psi
Thermal Properties
Latent Heat of Fusion
270 J/g
Maximum Temperature: Mechanical
600 °C 1110 °F
Melting Completion (Liquidus)
1450 °C 2650 °F
Melting Onset (Solidus)
1410 °C 2570 °F
Specific Heat Capacity
480 J/kg-K 0.11 BTU/lb-°F
Thermal Conductivity
26 W/m-K 15 BTU/h-ft-°F
Thermal Expansion
13 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
9.0 % IACS
Electrical Conductivity: Equal Weight (Specific)
10 % IACS
Otherwise Unclassified Properties
Base Metal Price
6.5 % relative
Density
7.8 g/cm3 490 lb/ft3
Embodied Carbon
2.0 kg CO2/kg material
Embodied Energy
28 MJ/kg 12 x 103 BTU/lb
Embodied Water
87 L/kg 10 gal/lb
Common Calculations
PREN (Pitting Resistance)
12
Resilience: Ultimate (Unit Rupture Work)
80 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
17 points
Strength to Weight: Bending
17 points
Thermal Diffusivity
6.9 mm2/s
Thermal Shock Resistance
13 points
Alloy Composition
Among alloy steels, the composition of ASTM A369 grade FP9 is notable for containing a comparatively high amount of chromium (Cr). Chromium is used to improve corrosion resistance and most mechanical properties (particularly at higher temperatures).
| Fe | 87.1 to 90.3 | |
| Cr | 8.0 to 10 | |
| Mo | 0.9 to 1.1 | |
| Si | 0.5 to 1.0 | |
| Mn | 0.3 to 0.6 | |
| C | 0 to 0.15 | |
| P | 0 to 0.030 | |
| S | 0 to 0.030 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
ASTM A369: Standard Specification for Carbon and Ferritic Alloy Steel Forged and Bored Pipe for High-Temperature Service