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### Elongation Chart for Common Bolting Materials

Bolt & Screw Torque Charts and Equations

Typical Elongation Chart for Common Bolting Materials

The amount of bolt stretch you want in your end ite design will, of course, be determined by the amount of preload you
want in the fastener. You won’t be able to answer the question until after you have considered
working loads on the bolt, and failure modes. stretch you might see in various bolts, per inch grip length, if they were loaded to 50% of their
yield strength. It would be advisable for you to calculate the expected stretch in
your application* or, better still,* by determining the preload–stretch
relationship experimentally, especially if your bolt has a grip-to-diameter ratio below 4:1.

Bolting Material |
20% of Yield |
40% of Yield |
60% of Yield |
80% of Yield |
100% of Yield |

Monel 40 K psi y.s. |
0.3 |
0.5 |
0.8 |
1.1 |
1.3 |

SAE GR 2 55 K psi y.s. |
0.4 |
0.7 |
1.1 |
1.5 |
1.8 |

SAE Grade 3; B7 and B16 over 4 in. diameter 80 K psi y.s. |
0.5 |
1.1 |
1.6 |
2.1 |
2.7 |

SAE Grade 5; A325; B7 and B16 up to 4 in. diameter 96 K psi y.s. |
0.6 |
1.3 |
1.9 |
2.6 |
3.2 |

SAE Grade 8; A490 120 K psi y.s. |
0.8 |
1.6 |
2.4 |
3.2 |
4.0 |

Inconel 718 180 K psi y.s. |
1.2 |
2.4 |
3.6 |
4.9 |
6.1 |

4340 steel, RC47 200 K psi y.s. |
1.3 |
2.7 |
4.0 |
5.3 |
6.6 |

Best available high-bolt material 240 K psi y.s. |
1.6 |
3.2 |
4.8 |
6.4 |
8.0 |

Titanium (6A14V) 134 K psi y.s. E = 17 x 10 ^{6} |
1.6 |
3.2 |
4.8 |
6.4 |
8.0 |

Note: Indicated elongation figures (in thousandths of an inch) are for various percentages of yield strengths (y.s.) of
different bolts with a 1 in. grip length. (Modulus of elasticity assumed to be 30 x 10^{6} unless otherwise noted.) To
obtain desired elongation for a particular metal, read the elongation figure under the appropriate percentage of yield
and multiply by the grip length in inches. For example, to obtain the expected elongation for an SAE Grade 5 bolt
stretched to 80% of yield, with a 5 in. grip length, select the appropriate figure, which in this case is 2.6, and multiply
by 5. The answer is 0.013 in. Note and warning: Many factors determine the "correct" stretch for a given fastener and
application. Use this table with caution.

Related:

- Bolt Torque on Assembly for Gasket Contact Stress per. ASME PCC-1 Equations and Calculator
- Bolt Root and Tensile Stress Area Table for Metric and Inch Unit Threads
- Bolt Elongation Formula and Calculator per. ASME PCC-1 When bolt elongation (bolt stretch) measurement is selected as the load-control technique to be used, the required bolt elongation is computed according to the following equation
- Bolt Threads, Grade, Bolt Strength, Excel Spreadsheet Calculator , Spreadsheet Calculated per the AISC Ninth Edition
- Bolt Pattern Group Pullout Excel Spreadsheet Calculator , Spreadsheet Calculator Calculated per the AISC Ninth Edition
- Engineering Fundamentals of Threaded Fastener Design and Analysis - Premium Membership Required
- Calculating Assembly Torque per ISO 68 & ISO 724
- Screw Stress Area 100 ksi & Greater
- Bolt Stress Area less Than 100 ksi
- Bolt Elongation Equation and Calculator while under Axial Stress
- ISO Hardware Engineering Data
- ANSI Hardware Engineering Data
- Hardware Supplier Manufacturer
- Strength of Materials

Reference:

- Source: Courtesy of Raymond Engineering Inc., Middletown, CT.