Boron Fiber Composite vs Kevlar 49
Composite · grade comparison
Boron Fiber Composite and Kevlar 49 are both composite grades. Kevlar 49 is the stronger of the two: tensile strength 3,000 MPa (435 ksi) against 1,500 MPa (218 ksi) for Boron Fiber Composite, about 100% more. Kevlar 49 is the more ductile: elongation 2.4% versus 0.75% for Boron Fiber Composite. Kevlar 49 is lighter (1.44 g/cm³ vs 2 g/cm³ for Boron Fiber Composite) and Boron Fiber Composite is stiffer (205 GPa vs 112 GPa). On the shop floor, Kevlar 49 machines more easily (poor vs not recommended).
Kevlar 49Choose it when strength drives the design, or when the part is bent, formed or impact-loaded.
Boron Fiber Composite vs Kevlar 49: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all composite grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
How to read these bars
- One bar per material. A full bar is the highest value among all composite grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
Boron Fiber CompositeKevlar 49
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Elastic (Young's) Modulus
Shear Modulus
Poisson's Ratio
Tensile Strength (Ultimate)
Elongation at Break
Compressive Strength
Compressive Modulus
Flexural Strength
Flexural Modulus
Shear Strength
Fracture Toughness (K_IC)
Izod Impact, Notched
Hardness, Shore D
Hardness, Rockwell M
Physical
Density and transition temperatures.
Density
Glass Transition (Tg)
Water Absorption (24 h)
Water Absorption (Saturation)
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Min Service Temperature
Limiting Oxygen Index
Max Service Temperature (short-term)
Electrical
Conductivity and insulation.
Electrical Resistivity
Dielectric Constant (1 MHz)
Dissipation Factor (1 MHz)
Volume Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
UV / Weathering Resistance
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Polishability
Mold Temperature (typ.)
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Same in both: Typical Recycled Content 0%
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Specific Stiffness (E / density)
Thermal Diffusivity
Thermal Shock Resistance Index
Strength versus weight
Yield strength against density for every composite grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
Manufacturing and finishing
| Capability | Boron Fiber Composite | Kevlar 49 |
|---|---|---|
| Default condition | — | — |
| Relative cost | $$$$ High | $$$$ High |
| Min. machined wall | — | — |
| Best machined surface | — | — |
Boron Fiber Composite vs Kevlar 49 — frequently asked
Is Kevlar 49 stronger than Boron Fiber Composite?
Yes. Kevlar 49 has a typical tensile strength of 3,000 MPa (435 ksi) against 1,500 MPa (218 ksi) for Boron Fiber Composite — about 100% more.
Which is cheaper, Boron Fiber Composite or Kevlar 49?
Both sit in the same relative cost tier ($$$$, high); the part price will be decided by machining time, tolerance and quantity rather than by the material.
Which is easier to machine, Boron Fiber Composite or Kevlar 49?
Kevlar 49. Its machinability rates poor (25/100) against not recommended (8/100) for Boron Fiber Composite.
Ready to make it?
Upload a CAD file and FabDigit prices the part in Boron Fiber Composite and Kevlar 49 side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.
Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.