# Cold Finished 8740 Ni-Cr-Mo Steel

Cold finished SAE-AISI 8740 is SAE-AISI 8740 steel in the cold worked (strain hardened) condition. The graph bars on the material properties cards below compare cold finished SAE-AISI 8740 to: SAE-AISI wrought 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

200

Elastic (Young's, Tensile) Modulus

190 *GPa* 27 *x 10 ^{6} psi*

Elongation at Break

11 *%*

Fatigue Strength

350 *MPa* 51 *x 10 ^{3} psi*

Poisson's Ratio

0.29

Shear Modulus

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

Shear Strength

400 *MPa* 58 *x 10 ^{3} psi*

Tensile Strength: Ultimate (UTS)

670 *MPa* 97 *x 10 ^{3} psi*

Tensile Strength: Yield (Proof)

570 *MPa* 82 *x 10 ^{3} psi*

## Thermal Properties

Latent Heat of Fusion

250 *J/g*

Maximum Temperature: Mechanical

410 *°C* 780 *°F*

Melting Completion (Liquidus)

1460 *°C* 2660 *°F*

Melting Onset (Solidus)

1420 *°C* 2580 *°F*

Specific Heat Capacity

470 *J/kg-K* 0.11 *BTU/lb-°F*

Thermal Conductivity

39 *W/m-K* 22 *BTU/h-ft-°F*

Thermal Expansion

13 *µm/m-K*

## Electrical Properties

Electrical Conductivity: Equal Volume

7.3 *% IACS*

Electrical Conductivity: Equal Weight (Specific)

8.4 *% IACS*

## Otherwise Unclassified Properties

Base Metal Price

2.6 *% relative*

Density

7.8 *g/cm ^{3}* 490

*lb/ft*

^{3}Embodied Carbon

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

Embodied Energy

20 *MJ/kg* 8.8 *x 10 ^{3} BTU/lb*

Embodied Water

50 *L/kg* 6.0 *gal/lb*

## Common Calculations

Resilience: Ultimate (Unit Rupture Work)

71 *MJ/m ^{3}*

Resilience: Unit (Modulus of Resilience)

850 *kJ/m ^{3}*

Stiffness to Weight: Axial

13 *points*

Stiffness to Weight: Bending

24 *points*

Strength to Weight: Axial

24 *points*

Strength to Weight: Bending

22 *points*

Thermal Diffusivity

10 *mm ^{2}/s*

Thermal Shock Resistance

20 *points*

## Alloy Composition

Fe | 96.5 to 97.7 | |

Mn | 0.75 to 1.0 | |

Ni | 0.4 to 0.7 | |

Cr | 0.4 to 0.6 | |

C | 0.38 to 0.43 | |

Si | 0.15 to 0.35 | |

Mo | 0.2 to 0.3 | |

S | 0 to 0.040 | |

P | 0 to 0.035 |

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

## Followup Questions

## Further Reading

ASTM A322: Standard Specification for Steel Bars, Alloy, Standard Grades

ASM Specialty Handbook: Carbon and Alloy Steels, J. R. Davis (editor), 1996

Manufacture and Uses of Alloy Steels, Henry D. Hibbard, 2005

Steels: Processing, Structure, and Performance, 2nd ed., George Krauss, 2015