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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).

Iron (Fe) 87.1 to 90.3
Chromium (Cr) 8.0 to 10
Molybdenum (Mo) 0.9 to 1.1
Silicon (Si) 0.5 to 1.0
Manganese (Mn) 0.3 to 0.6
Carbon (C) 0 to 0.15
Phosphorus (P) 0 to 0.030
Sulfur (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