AS4C
Grade
AS4C = 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.
Values for the AS4C 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 | — | — |
AS4CThis page 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 | — |
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 AS4C?
AS4C is AS4 in the AS4C grade — pick when thinner filaments and slightly lower fiber density improve fabric drape and translation in thin laminates. AS4C has a tensile strength of 4,340 MPa (629 ksi), stronger than 91% of composite grades. Elongation at break is 1.8% and the elastic modulus is 231 GPa (33.5 Msi). AS4C has a density of 1.78 g/cm³ (0.0643 lb/in³), heavier than 53% of composite grades. FIBER-12K is the default condition FabDigit quotes; AS4C is available on request or by drawing note.
Advantages
- Good corrosion resistance — 90/100, better than 85% of composite grades
- Stiff — 231 GPa (33.5 Msi), better than 84% of composite grades
- High service temperature — 400°C (752 °F), better than 78% of composite grades
AS4C properties
Typical room-temperature values for AS4C; 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
AS4C has a density of 1.78 g/cm³ (0.0643 lb/in³), heavier than 53% of composite grades.
Mechanical4
AS4C has a tensile strength of 4,340 MPa (629 ksi), stronger than 91% of composite grades. Elongation at break is 1.8% and the elastic modulus is 231 GPa (33.5 Msi).
Thermal6
AS4C 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 -0.4 µm/m·K (-0.222 µin/in·°F).
Electrical1
AS4C has an electrical resistivity of 1.7×10⁻⁵ Ω·m.
Chemical & Environmental2
Corrosion resistance is excellent (90/100), better than 85% of composite grades.
Sustainability3
Producing a kilogram of AS4C takes about 320 MJ of energy and emits 24 kg of CO₂ — more than 72% of composite grades. Typical recycled content is 0%.
Manufacturability1
AS4C'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 AS4C
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 |
AS4C — frequently asked
What is AS4C used for?
AS4C 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 AS4C?
AS4C has a typical tensile strength of 4,340 MPa (629 ksi) — stronger than 91% of composite grades. Strength varies by condition: see the 7 listed tempers.
Is AS4C 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 AS4C 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 AS4C?
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 AS4C 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 AS4C?
AS4C 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.