# Cold Finished 8645 Ni-Cr-Mo Steel

Cold finished SAE-AISI 8645 is SAE-AISI 8645 steel in the cold worked (strain hardened) condition. The graph bars on the material properties cards below compare cold finished SAE-AISI 8645 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

12 *%*

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)

560 *MPa* 81 *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* 2650 *°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* 8.7 *x 10 ^{3} BTU/lb*

Embodied Water

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

## Common Calculations

Resilience: Ultimate (Unit Rupture Work)

77 *MJ/m ^{3}*

Resilience: Unit (Modulus of Resilience)

840 *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 | 0.43 to 0.48 | |

Si | 0.15 to 0.35 | |

Mo | 0.15 to 0.25 | |

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

CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015

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