Kevlar 49
Kevlar 49 is a high-modulus para-aramid fiber (density 1.44 g/cm³, tensile strength 3000 MPa, elastic modulus 112 GPa, elongation 2.4 %) and the most common aramid grade for structural composite laminates.
Reference datasheet — Kevlar 49 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Kevlar 49 grades and fills
Kevlar 49 is supplied in 5 conditions, soft to hard.
Compare all 5 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Woven fabric / epoxy laminate, Vf ≈ 50 % | Design values for quasi-isotropic hand-layup or infused panels (hulls, radomes, impact skins). | 480 | 1.9 | ||
Kevlar 49 / carbon hybrid fabric laminate | Pick when carbon stiffness/compression must be combined with aramid impact and splinter containment. | 620 | 1.4 | 88 Shore D | |
Epoxy prepreg (UD or woven, 120–180 °C cure) | Pick for autoclave/oven-cured aerospace and sporting-goods laminates needing repeatable fiber volume and resin content. | 1,350 | 1.8 | 86 Shore D | |
Unidirectional Kevlar 49 / epoxy laminate, Vf ≈ 60 % | Design values for 0° dominated tension-critical structures (pressure vessels, tension members). | 1,380 | 1.8 | ||
Chopped fiber (3–12 mm) for compounds and friction materials | Pick for thermoplastic/thermoset compounding, brake and gasket materials, and asbestos replacement. | 3,000 | 2.4 |
Supply forms, finishes and certifications
Ways Kevlar 49 is supplied — form, process route, surface or paperwork — without a datasheet of their own. A reinforced fill changes stiffness and elongation; the branded products above carry the filled values.
| Option | What it is | Type |
|---|---|---|
ROVING | Roving / tow for filament winding and pultrusion | Supply form |
YARNDefault | Continuous filament yarn | Supply form |
FABRIC | Woven fabric | Reinforcement |
What is Kevlar 49?
Kevlar 49 is a high-modulus para-aramid fiber (density 1.44 g/cm³, tensile strength 3000 MPa, elastic modulus 112 GPa, elongation 2.4 %) and the most common aramid grade for structural composite laminates. It is chosen for stiffness-to-weight and impact/damage tolerance, and is available as yarn, roving, chopped fiber, woven fabric, epoxy prepreg, unidirectional tape and carbon-hybrid layups. Limits are a maximum service temperature near 160 °C, low compressive strength, moisture pickup and poor UV stability; machinability rates only 25, so cutting and drilling are slow and tool-intensive. Kevlar 29 is the cheaper choice when toughness rather than stiffness controls. Kevlar 49 has a density of 1.44 g/cm³ (0.052 lb/in³), lighter than 61% of composite grades. Its glass-transition temperature is 360°C (680 °F). Kevlar 49 has a tensile strength of 3,000 MPa (435 ksi), stronger than 81% of composite grades. Elongation at break is 2.4% and the elastic modulus is 112 GPa (16.2 Msi).
What is Kevlar 49 used for?
- aerospace composite panels
- boat hulls
- pressure vessels
- sporting goods
- armor laminates
Limitations
- Degrades in UV without stabilisers — 20/100, worse than 94% of composite grades
- Poor heat conductor — 0.04 W/m·K (0.0231 BTU/hr·ft·°F), worse than 91% of composite grades
Kevlar 49 properties
Typical room-temperature values; bars are the position among composite grades.
Physical3
Kevlar 49 has a density of 1.44 g/cm³ (0.052 lb/in³), lighter than 61% of composite grades. Its glass-transition temperature is 360°C (680 °F).
Mechanical5
Kevlar 49 has a tensile strength of 3,000 MPa (435 ksi), stronger than 81% of composite grades. Elongation at break is 2.4% and the elastic modulus is 112 GPa (16.2 Msi).
Thermal8
Kevlar 49 is rated for continuous service to 160°C (320 °F). It conducts heat at 0.04 W/m·K (0.0231 BTU/hr·ft·°F), worse than 91% of composite grades. Thermal expansion is -2 µm/m·K (-1.11 µin/in·°F).
Electrical4
Kevlar 49 has an electrical resistivity of 1×10¹³ Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (70/100), worse than 64% of composite grades. UV resistance is poor.
Sustainability3
Producing a kilogram of Kevlar 49 takes about 280 MJ of energy and emits 17 kg of CO₂ — more than 63% of composite grades. Typical recycled content is 0%.
Manufacturability1
Kevlar 49's machinability is poor (25/100, worse than 65% of composite grades).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the composite family
Yield strength against density for every composite grade FabDigit runs. Kevlar 49 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Kevlar 49
Is Kevlar 49 easy to machine?
Cut with serrated/shear scissors, hot knife or abrasive waterjet; drilling needs brad-point or dagger drills with backing to stop fuzzing and delamination — carbide tools dull quickly.
Can Kevlar 49 be welded?
Not weldable; join by adhesive bonding, co-cured resin joints or mechanical fasteners with bushings to avoid fiber crushing.
Can Kevlar 49 be formed, bent or molded?
Excellent drape for hand layup, RTM/infusion, braiding and filament winding; dry the fiber (~4 h at 100–120 °C) before impregnation and use low-viscosity resin plus vacuum to fully wet the yarns.
Kevlar 49 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| p-phenylenediamine (PPD) monomer unitas-polymerized mole basis | ≈ 45 | 45 |
| terephthaloyl chloride (TCl) monomer unias-polymerized mole basis | ≈ 55 | 55 |
| surface finish / sizingform-dependent (weaving, epoxy-compatible or none) | 0 – 1 | 0.3 |
| poly(p-phenylene terephthalamide) (PPTA)condensation polymer of p-phenylenediamine and terephthaloyl chloride; ~0.1–1 % surface finish/sizing depending on form | balance |
What surface finishes work on Kevlar 49?
Seal all cut edges with resin to block moisture wicking; sanding leaves fuzz, so use peel-ply for bond surfaces and pigmented/UV-blocking topcoats or gelcoat for outdoor exposure.
How much does Kevlar 49 cost?
Kevlar 49 is a high-cost composite ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Kevlar 49 — frequently asked
What is Kevlar 49 used for?
Kevlar 49 is typically used for aerospace composite panels, boat hulls, pressure vessels, sporting goods and armor laminates. In short: standard structural aramid fiber; best impact-to-weight laminate; poor compressive strength.
What is the tensile strength of Kevlar 49?
Kevlar 49 has a typical tensile strength of 3,000 MPa (435 ksi) — stronger than 81% of composite grades. Strength varies by condition: see the 5 listed tempers.
Is Kevlar 49 easy to machine?
Not especially — machinability is rated poor (25/100, worse than 65% of composite grades). Cut with serrated/shear scissors, hot knife or abrasive waterjet; drilling needs brad-point or dagger drills with backing to stop fuzzing and delamination — carbide tools dull quickly.
Can Kevlar 49 be welded?
Not weldable; join by adhesive bonding, co-cured resin joints or mechanical fasteners with bushings to avoid fiber crushing.
What surface finishes work on Kevlar 49?
Seal all cut edges with resin to block moisture wicking; sanding leaves fuzz, so use peel-ply for bond surfaces and pigmented/UV-blocking topcoats or gelcoat for outdoor exposure.
Can Kevlar 49 be formed, bent or molded?
Excellent drape for hand layup, RTM/infusion, braiding and filament winding; dry the fiber (~4 h at 100–120 °C) before impregnation and use low-viscosity resin plus vacuum to fully wet the yarns.
What is the maximum service temperature of Kevlar 49?
Kevlar 49 is rated for continuous use to about 160°C (320 °F), and briefly to 250°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does Kevlar 49 cost?
Kevlar 49 is a high-cost composite ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- Kevlar Aramid Fiber Technical Guide (Kevlar 49 properties) — DuPont (2017)
- ASM Handbook Vol. 21: Composites — ASM International (2001)
- CMH-17 (MIL-HDBK-17) Composite Materials Handbook, Vol. 3 Polymer Matrix Composites — SAE International / CMH-17 (2012)
- ASTM D7269 – Tensile Testing of Aramid Yarns — ASTM (2017)
- CES/Granta EduPack eco and mechanical data, aramid fiber & KFRP records — Ansys Granta (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.