# 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 10 ^{6} psi*

Elongation at Break

20 *%*

Fatigue Strength

160 *MPa* 24 *x 10 ^{3} psi*

Poisson's Ratio

0.28

Shear Modulus

75 *GPa* 11 *x 10 ^{6} psi*

Shear Strength

300 *MPa* 43 *x 10 ^{3} psi*

Tensile Strength: Ultimate (UTS)

470 *MPa* 69 *x 10 ^{3} psi*

Tensile Strength: Yield (Proof)

240 *MPa* 34 *x 10 ^{3} 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/cm ^{3}* 490

*lb/ft*

^{3}Embodied Carbon

2.0 *kg CO _{2}/kg material*

Embodied Energy

28 *MJ/kg* 12 *x 10 ^{3} BTU/lb*

Embodied Water

87 *L/kg* 10 *gal/lb*

## Common Calculations

PREN (Pitting Resistance)

12

Resilience: Ultimate (Unit Rupture Work)

80 *MJ/m ^{3}*

Resilience: Unit (Modulus of Resilience)

140 *kJ/m ^{3}*

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 *mm ^{2}/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