AS4D
Grade
AS4D = higher-modulus/higher-strength member of the AS4 family
Pick when a drop-in stiffness/strength upgrade over AS4 is wanted without moving to IM7.
Values for the AS4D condition
Other AS4 grades and fills
AS4 is listed in 7 conditions; see the grade overview at AS4.
Compare all 7 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
AS4/BMI unidirectional laminate | Pick when service temperature above the epoxy limit (to ~200–230 °C) is required with the same standard-modulus fiber. | — | 2,050 | 1.4 | — |
APC-2/AS4 | Pick for tough, solvent-resistant, weldable thermoplastic structure and continuous service near 250 °C. | — | 2,130 | — | — |
AS4/8552 unidirectional toughened epoxy laminate | Pick for current-production primary/secondary aerospace structure needing better damage tolerance and hot/wet retention than 3501-6. | — | 2,200 | — | — |
AS4/3501-6 unidirectional epoxy laminate | Pick this classic 177 °C-cure epoxy UD system when legacy aerospace allowables and extensive published data are required. | — | 2,280 | — | — |
Fine-filament (5.1 µm) variant of AS4 | Pick when thinner filaments and slightly lower fiber density improve fabric drape and translation in thin laminates. | — | 4,340 | 1.8 | — |
FIBER-12KDefault AS4 12K dry tow | Pick for filament winding, weaving, braiding or in-house prepregging where the bare standard-modulus tow is needed. | — | 4,433 | 1.8 | — |
AS4DThis page Higher-modulus/higher-strength member of the AS4 family | Pick when a drop-in stiffness/strength upgrade over AS4 is wanted without moving to IM7. | — | 4,830 | 2 | — |
What is AS4D?
AS4D is AS4 in the AS4D grade — pick when a drop-in stiffness/strength upgrade over AS4 is wanted without moving to IM7. AS4D has a tensile strength of 4,830 MPa (701 ksi), stronger than 95% of composite grades. Elongation at break is 2% and the elastic modulus is 241 GPa (35 Msi). AS4D has a density of 1.79 g/cm³ (0.0647 lb/in³), heavier than 56% of composite grades. FIBER-12K is the default condition FabDigit quotes; AS4D is available on request or by drawing note.
Advantages
- Stiff — 241 GPa (35 Msi), better than 86% of composite grades
- Good corrosion resistance — 90/100, better than 85% of composite grades
- High service temperature — 400°C (752 °F), better than 78% of composite grades
AS4D properties
Typical room-temperature values for AS4D; 10 are specific to this condition. Other listed values are AS4 reference data and may not represent this condition. 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 4,830 MPa (701 ksi), stronger than 95% of composite grades. Elongation at break is 2% and the elastic modulus is 241 GPa (35 Msi).
Thermal6
AS4D is rated for continuous service to 400°C (752 °F). It conducts heat at 7 W/m·K (4.04 BTU/hr·ft·°F), better than 69% of composite grades. Thermal expansion is -0.4 µm/m·K (-0.222 µin/in·°F).
Electrical1
AS4D has an electrical resistivity of 1.6×10⁻⁵ Ω·m.
Chemical & Environmental2
Corrosion resistance is excellent (90/100), better than 85% of composite grades.
Sustainability3
Producing a kilogram of AS4D takes about 320 MJ of energy and emits 24 kg of CO₂ — more than 72% of composite grades. Typical recycled content is 0%.
Manufacturability1
AS4D's machinability is poor (30/100, worse than 54% of composite grades).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with AS4D
Is AS4 easy to machine?
Highly abrasive and delamination-prone — use PCD/diamond-coated tools, high speed with low feed, sharp compression routers, backing plates and dust extraction (conductive dust).
Can AS4 be welded?
Not weldable in epoxy/BMI form (bond or bolt); APC-2/PEEK versions can be resistance-, induction- or ultrasonically welded.
Can AS4 be formed, bent or molded?
Autoclave cure of prepreg (177 °C / 0.6–0.7 MPa for 3501-6 and 8552), or filament winding/RTM with dry tow; thermoplastic AS4/PEEK tape is press- or AFP-consolidated at 380–400 °C.
What surface finishes work on AS4?
Peel-ply or light abrasion plus solvent wipe before bonding; UV-protective primer/topcoat is needed outdoors, and glass or fiberglass isolation plies plus sealant are required at aluminium interfaces to prevent galvanic corrosion.
AS4 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 |
|---|---|---|
| carbon (C)PAN-based fiber, non-graphitized standard modulus | 93.5 – 95.5 | 94 |
| nitrogen (N)residual from PAN precursor | 3.5 – 6 | 5 |
| oxygen + hydrogen (surface/residual)surface-treated (oxidized) fiber | 0.3 – 1.5 | 0.8 |
| sizing (epoxy-compatible)GP/unsized/thermoplastic-compatible options available | 0.6 – 1.5 | 1 |
AS4D — frequently asked
What is AS4D used for?
AS4D is typically used for aircraft secondary structures, industrial tooling, sporting goods and automotive parts. In short: standard-modulus workhorse fiber; lowest-cost aerospace prepreg fiber; deepest allowables database.
What is the tensile strength of AS4D?
AS4D has a typical tensile strength of 4,830 MPa (701 ksi) — stronger than 95% of composite grades. Strength varies by condition: see the 7 listed tempers.
Is AS4D easy to machine?
Not especially — machinability is rated poor (30/100, worse than 54% of composite grades). Highly abrasive and delamination-prone — use PCD/diamond-coated tools, high speed with low feed, sharp compression routers, backing plates and dust extraction (conductive dust).
Can AS4D be welded?
Not weldable in epoxy/BMI form (bond or bolt); APC-2/PEEK versions can be resistance-, induction- or ultrasonically welded.
What surface finishes work on AS4D?
Peel-ply or light abrasion plus solvent wipe before bonding; UV-protective primer/topcoat is needed outdoors, and glass or fiberglass isolation plies plus sealant are required at aluminium interfaces to prevent galvanic corrosion.
Can AS4D be formed, bent or molded?
Autoclave cure of prepreg (177 °C / 0.6–0.7 MPa for 3501-6 and 8552), or filament winding/RTM with dry tow; thermoplastic AS4/PEEK tape is press- or AFP-consolidated at 380–400 °C.
What is the maximum service temperature of AS4D?
AS4D is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- HexTow AS4 / AS4C / AS4D Carbon Fiber Product Data — Hexcel (2020)
- HexPly 8552 Epoxy Matrix Product Data Sheet — Hexcel (2020)
- ASM Handbook Vol. 21: Composites — ASM International (2001)
- MIL-HDBK-17 / CMH-17 Composite Materials Handbook (AS4/3501-6, AS4/8552 data sets) — SAE / CMH-17 (2012)
- APC-2/AS4 Thermoplastic Composite Tape Data — Cytec/Solvay (2015)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.