Elongation Chart for Common Bolting Materials
Elongation of nine common bolting materials — from Monel to 240 ksi high-strength steel — at 20% through 100% of yield strength, showing how much elastic-plus-plastic stretch each material delivers as bolt stress rises.
Last updated: 2026-11
Specifications
A bolted joint's resilience comes from how far its bolts can stretch. This chart tabulates elongation for nine common bolting materials at five stress levels — 20%, 40%, 60%, 80% and 100% of each material's yield strength — so you can compare not just strength but stretch. The pattern across the rows is the trade-off every fastener engineer knows: low-strength materials stretch plenty in relative terms at low fractions of yield (SAE GR 2: 0.4 units at 20% of 55 ksi), high-strength materials need higher absolute stress before they give the same elongation (4340 at RC 47: 1.3 at 20% of 200 ksi), and at 100% of yield every material's elongation is roughly proportional to its yield strength. The last two rows bracket the practical ceiling: "best available high-bolt material" at 240 ksi and titanium (6A14V per the source's label) at 134 ksi with a stated E of 17 x 10 6 — the titanium row matches the 240-ksi steel's elongation fractions because its lower modulus stretches further per unit stress. Use the chart to compare joint resilience candidate materials, not to set working stresses — the tabulated fractions describe behaviour up to yield, not allowable design stress. Material certifications and supply forms are per RFQ.
| Materials covered | Monel (40 ksi y.s.), SAE GR 2 (55 ksi), SAE Grade 3 / B7 / B16 over 4 in. (80 ksi), SAE Grade 5 / A325 / B7-B16 up to 4 in. (96 ksi), SAE Grade 8 / A490 (120 ksi), Inconel 718 (180 ksi), 4340 steel RC47 (200 ksi), best available high-bolt material (240 ksi), titanium 6A14V (134 ksi, E = 17 x 10 6) |
|---|---|
| Stress levels | 20%, 40%, 60%, 80% and 100% of each material's yield strength |
| Reading | Elongation values as printed; e.g. SAE Grade 8/A490: 0.8 at 20% of yield rising to 4.0 at 100% |
| Use | Comparing stretch/resilience between bolting material candidates at matched fractions of yield |
| Not tabulated | Allowable design stresses, temperature derating, galled/creep behaviour, certification basis — per RFQ |
| 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 |
- Row 9 (Titanium (6A14V) 134 K psi y.s. E = 17 x 10 6): titanium designation prints "6A14V" (the common alloy is 6Al-4V); carried verbatim, not normalized
- Row 8 (Best available high-bolt material 240 K psi y.s.): "Best available high-bolt material" is the source's own label, not a standardized designation; carried verbatim
Materials
- Every row is a material family the tenant supplies or outsources: carbon-steel property classes (GR 2, Grade 5/8, B7/B16), stainless and nickel alloys (Monel, Inconel 718), alloy steels (4340) and titanium. State the material, the joint's operating temperature and any required certs (EN 10204 3.1, NACE, aerospace) with the RFQ — elongation behaviour at temperature and the certified heat lot properties are confirmed per order, not from this chart
Ordering & documentation
Documents
Shipments are backed by Mill Test Certificate (MTC), Dimensional Report, Salt Spray Test Report on request, with full batch traceability from raw material to finished product. Quality management follows the owner-confirmed compliance list: ISO 9001:2015, RoHS, REACH. Exact document sets are confirmed on the order.
Quotation
- The fastener family (Elongation Chart for Common Bolting Materials) plus the standard designation from your drawing — DIN / ISO / JIS / ASTM / ANSI, or a drawing for custom parts.
- Size (diameter and length), thread type (metric or inch), property class or grade, and coating or finish.
- Quantity per size and your target delivery date.
- Destination country, and any required documents (for example a mill test certificate) so the quote includes them.
Sample & supply
Minimum order quantity is 1,000–10,000 pieces depending on size. Stock items run 3–7 days. High-strength and custom parts run 15–25 days. Quantities or variants outside the standard range are confirmed at quotation.
Storage & shipping
Parts are packed for export and shipped factory-direct to buyers in Europe, Asia, the Americas and the Middle East. Store fasteners dry and protected until installation, and keep coated parts in their packaging until use; specific packing and preservation requirements can be stated on the order and confirmed at quotation.
Frequently asked questions
What is this elongation chart actually telling me when I pick between a Grade 8 bolt and an Inconel 718 bolt?
How much warning each material gives you before things go wrong. At the same fraction of yield, the stronger material stretches less: at 20% of yield, Grade 8 (120 ksi) elongates 0.8 while Inconel 718 (180 ksi) elongates 1.2 — the nickel alloy is both stronger and more compliant per unit stress, which is why it is chosen where a joint must stay elastic under high load and temperature. Read across a row: elongation roughly doubles from each 20% step to the next, so a bolt tightened to 80% of yield has four times the stretch it had at 20% — that stored stretch is what keeps the joint clamped when the load fluctuates. What the chart does not do: it is not an allowable-stress table. Design limits come from the governing code and the material certificate, not from these fractions. Quote material, class and certs per RFQ.
Why do the titanium row and the 240-ksi steel row show identical elongation values?
Because elongation at a fraction of yield scales inversely with the elastic modulus, and these two materials offset each other: the 240-ksi steel has roughly 40% more yield strength but also a higher modulus, while titanium's stated E of 17 x 10 6 (about 80% of steel's ~29 x 10 6) means it stretches further per unit stress — at 100% of yield both arrive at 8.0. It is a useful reminder that stiffness and strength are independent axes: substituting titanium for high-strength steel keeps the same relative-stretch behaviour at a lower absolute stress, at lower weight. The row label prints "6A14V" for the titanium alloy (the common designation is 6Al-4V) — carried verbatim from the collected page. For actual substitution decisions, confirm strength, temperature and galvanic compatibility per RFQ.
Related knowledge
- What Bolt Property Classes 8.8, 10.9 and 12.9 Encode — and When High Strength Stops Being the Right Choice
- Bolt Grade Selection: ISO 898-1 8.8/10.9/12.9 vs ASTM A307 and A325
- 8.8 vs 10.9 vs 12.9 Bolts: Strength, Hardness and Cost — What the Evidence Settles
- Calculating Bolt Preload and Clamp Force: Torque, Friction and Tightening Method
- How to Determine Tightening Torque and Choose a Tightening Method for a Bolted Joint
- Fastener Failure Modes: Which Fatigue, Creep and SCC Controls the Evidence Supports
- Hydrogen Embrittlement in High-Strength Bolts: Which Grades Need Controls, Which Coatings and Baking Schedules Are Acceptable, and What to Require Before the RFQ
Request a Quote
Get factory-direct pricing from the manufacturer.
What to include in your inquiry
- ✓ Standard and property class (e.g. DIN 912, ISO 4762, class 8.8) — or a drawing for custom parts.
- ✓ Sizes, lengths and thread type (metric or inch).
- ✓ Quantity per size and your target delivery date.
- ✓ Destination country, plus any coating or finish requirement.
- ✓ Any documents you need with the shipment (e.g. mill test certificate) so the quote includes them.
- ✓ Your inquiry goes straight to the factory team by email and gets a reply within 24 hours.
- ✓ Factory-direct pricing
- ✓ Standard and custom specifications
- ✓ Factory-direct export to buyers in Europe, Asia, the Americas and the Middle East
- ✓ Full fastener family support