AS4 FIBER-12K
Grade · default condition
FIBER-12K = aS4 12K dry tow
Pick for filament winding, weaving, braiding or in-house prepregging where the bare standard-modulus tow is needed.
Values for the FIBER-12K 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-12KDefaultThis page 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 AS4 FIBER-12K?
AS4 FIBER-12K is AS4 in the FIBER-12K grade — pick for filament winding, weaving, braiding or in-house prepregging where the bare standard-modulus tow is needed. AS4 FIBER-12K has a tensile strength of 4,433 MPa (643 ksi), stronger than 92% of composite grades. Elongation at break is 1.8% and the elastic modulus is 231 GPa (33.5 Msi). AS4 FIBER-12K has a density of 1.79 g/cm³ (0.0647 lb/in³), heavier than 56% of composite grades.
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
AS4 FIBER-12K properties
Typical room-temperature values for AS4 FIBER-12K; 11 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
AS4 FIBER-12K has a density of 1.79 g/cm³ (0.0647 lb/in³), heavier than 56% of composite grades.
Mechanical4
AS4 FIBER-12K has a tensile strength of 4,433 MPa (643 ksi), stronger than 92% of composite grades. Elongation at break is 1.8% and the elastic modulus is 231 GPa (33.5 Msi).
Thermal6
AS4 FIBER-12K 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
AS4 FIBER-12K 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 AS4 FIBER-12K takes about 320 MJ of energy and emits 24 kg of CO₂ — more than 72% of composite grades. Typical recycled content is 0%.
Manufacturability1
AS4 FIBER-12K's machinability is poor (30/100, worse than 54% of composite grades).
Common Calculations4
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with AS4 FIBER-12K
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 |
AS4 FIBER-12K — frequently asked
What is AS4 FIBER-12K used for?
AS4 FIBER-12K 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 AS4 FIBER-12K?
AS4 FIBER-12K has a typical tensile strength of 4,433 MPa (643 ksi) — stronger than 92% of composite grades. Strength varies by condition: see the 7 listed tempers.
Is AS4 FIBER-12K 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 AS4 FIBER-12K 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 AS4 FIBER-12K?
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 AS4 FIBER-12K 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 AS4 FIBER-12K?
AS4 FIBER-12K 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.