AS4D
AS4D is a PAN-based, standard-modulus carbon fiber from Hexcel, an improved-strength development of AS4, supplied as 12K tow in sized (12K-GP) and unsized (12K-UC) form plus unidirectional and fabric epoxy prepreg (UD-EP60, FAB-EP) and chopped fiber.
Reference datasheet — AS4D 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.
AS4D grades and fills
AS4D is supplied in 3 conditions, soft to hard.
Compare all 3 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Woven fabric AS4D/epoxy laminate | Choose the plain or satin woven prepreg laminate made from 12K tow for draping over curved tools and quasi-isotropic parts; ~55 % Vf yields 900 MPa and 70 GPa. | 900 | 1.3 | 88 Shore D | |
Unidirectional AS4D/epoxy laminate, 60 % fiber volume | Use these cured aerospace-prepreg 0° values as design allowables for unidirectional primary structure: 2550 MPa, 148 GPa, 150 °C service and a Tg of 200 °C at 60 % fiber volume. | 2,550 | 1.7 | ||
Chopped / milled AS4D fiber for compounding | Use chopped or milled fiber to reinforce thermoset and thermoplastic compounds and to add conductivity or antistatic behaviour; there is no continuous load path, so laminate strength is not reached. | 4,400 | 1.8 |
Supply forms, finishes and certifications
Ways AS4D is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
12K-GPDefault | 12K tow, epoxy-compatible sizing | Surface finish |
12K-UC | 12K tow, unsized | Surface finish |
What is AS4D?
AS4D is a PAN-based, standard-modulus carbon fiber from Hexcel, an improved-strength development of AS4, supplied as 12K tow in sized (12K-GP) and unsized (12K-UC) form plus unidirectional and fabric epoxy prepreg (UD-EP60, FAB-EP) and chopped fiber. It is specified for structural aerospace prepreg systems, offering 4480 MPa tensile strength, 245 GPa modulus and 1.8 % elongation at 1.79 g/cm3, with fiber stability to 400 °C. In practice the matrix sets the service limit, laminates are not weldable, and carbon is galvanically aggressive to aluminum fittings. HTS40 or T700-class fiber is the usual commercial alternative. AS4D has a density of 1.79 g/cm³ (0.0647 lb/in³), heavier than 56% of composite grades. AS4D has a tensile strength of 4,480 MPa (650 ksi), stronger than 93% of composite grades. Elongation at break is 1.8% and the elastic modulus is 245 GPa (35.5 Msi).
What is AS4D used for?
- aircraft structures
- rocket components
- industrial composites
Advantages
- Stiff — 245 GPa (35.5 Msi), better than 86% of composite grades
- High service temperature — 400°C (752 °F), better than 78% of composite grades
Limitations
- Difficult to machine — 15/100, worse than 84% of composite grades
- High embodied carbon — 30 kg CO₂/kg, worse than 80% of composite grades
AS4D properties
Typical room-temperature values; bars are the position among composite grades.
Physical1
AS4D has a density of 1.79 g/cm³ (0.0647 lb/in³), heavier than 56% of composite grades.
Mechanical4
AS4D has a tensile strength of 4,480 MPa (650 ksi), stronger than 93% of composite grades. Elongation at break is 1.8% and the elastic modulus is 245 GPa (35.5 Msi).
Thermal6
AS4D is rated for continuous service to 400°C (752 °F). It conducts heat at 6.8 W/m·K (3.93 BTU/hr·ft·°F), better than 67% of composite grades. Thermal expansion is -0.6 µm/m·K (-0.333 µin/in·°F).
Electrical2
AS4D has an electrical resistivity of 1.5×10⁻⁵ Ω·m.
Chemical & Environmental3
Corrosion resistance is excellent (85/100), better than 65% of composite grades. UV resistance is excellent.
Sustainability4
Producing a kilogram of AS4D takes about 400 MJ of energy and emits 30 kg of CO₂ — more than 77% of composite grades. Typical recycled content is 0%.
Manufacturability1
AS4D's machinability is poor (15/100, worse than 84% 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. AS4D is highlighted; hover a dot for its name, or open the interactive family chart.
Working with AS4D
Is AS4D easy to machine?
Cured parts must be cut with diamond-coated or PCD tooling at high spindle speed and low feed, with dust extraction at the cutter. This limits delamination and fiber breakout and keeps conductive carbon dust out of the air and out of electrical equipment.
Can AS4D be welded?
Not weldable; join by adhesive bonding (abraded or peel-ply prepared surfaces) or by mechanical fasteners with bushings. Use titanium or A286 fasteners to avoid galvanic corrosion against the carbon.
Can AS4D be formed, bent or molded?
Cure prepreg in an autoclave or heated press at typically 177 °C / 0.6 MPa, or process by tow winding, RTM and automated fiber placement. Control bend radius and tension on dry fiber to avoid abrasion and fuzz build-up.
AS4D 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 |
|---|---|---|
| Ccarbon content (carbonized PAN precursor) | 93.5 – 95 | 94 |
| Nresidual nitrogen | 3.5 – 6 | 5 |
| Osurface oxygen from electrochemical treatment | 0.3 – 1.5 | 0.8 |
| epoxy sizingGP sizing; 0 for UC (unsized) grade | 0.7 – 1.3 | 1 |
What surface finishes work on AS4D?
Sand and prime with epoxy primer, then apply a polyurethane topcoat. At interfaces with aluminum alloys add a glass-cloth or adhesive-film isolation layer, and surface-treat bond faces to raise joint strength.
How much does AS4D cost?
AS4D 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.
AS4D — frequently asked
What is AS4D used for?
AS4D is typically used for aircraft structures, rocket components and industrial composites. In short: improved-strength AS4 variant; aerospace prepreg workhorse; high-strain standard modulus.
What is the tensile strength of AS4D?
AS4D has a typical tensile strength of 4,480 MPa (650 ksi) — stronger than 93% of composite grades. Strength varies by condition: see the 3 listed tempers.
Is AS4D easy to machine?
Not especially — machinability is rated poor (15/100, worse than 84% of composite grades). Cured parts must be cut with diamond-coated or PCD tooling at high spindle speed and low feed, with dust extraction at the cutter. This limits delamination and fiber breakout and keeps conductive carbon dust out of the air and out of electrical equipment.
Can AS4D be welded?
Not weldable; join by adhesive bonding (abraded or peel-ply prepared surfaces) or by mechanical fasteners with bushings. Use titanium or A286 fasteners to avoid galvanic corrosion against the carbon.
What surface finishes work on AS4D?
Sand and prime with epoxy primer, then apply a polyurethane topcoat. At interfaces with aluminum alloys add a glass-cloth or adhesive-film isolation layer, and surface-treat bond faces to raise joint strength.
Can AS4D be formed, bent or molded?
Cure prepreg in an autoclave or heated press at typically 177 °C / 0.6 MPa, or process by tow winding, RTM and automated fiber placement. Control bend radius and tension on dry fiber to avoid abrasion and fuzz build-up.
What is the maximum service temperature of AS4D?
AS4D is rated for continuous use to about 400°C (752 °F), and briefly to 500°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does AS4D cost?
AS4D 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
- HexTow AS4D Carbon Fiber Product Data Sheet — Hexcel (2020)
- HexPly 8552 / 3501-6 Epoxy Prepreg Data Sheets — Hexcel (2020)
- ASM Handbook Vol.21: Composites — ASM International (2001)
- CMH-17 Composite Materials Handbook, Vol.2 Polymer Matrix Composites — SAE International (2012)
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.