Aluminum AC4B
JIS AC4B
AC4B is a JIS Al-Si-Cu casting alloy (close to A319.0, ZL107 and 380.0) in which 2–4 % Cu raises strength and machinability over Al-Si-Mg grades.
Reference datasheet — AC4B 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.
Values for the F condition
AC4B tempers and conditions
AC4B is supplied in 4 conditions, soft to hard. F is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
FDefault As fabricated | Default and cheapest condition; use where moderate strength and good dimensional stability after machining are enough. | 110 | 180 | 2 | 75 HB | 27 % IACS |
Cooled from hot working and artificially aged | Low-cost ageing only (no solution treatment): raises hardness and stabilises dimensions with minimal distortion risk. | 150 | 210 | 1.5 | 82 HB | 28 % IACS |
Solution heat treated and overaged (stabilized) | Overaged for maximum dimensional stability at elevated temperature; some strength traded for stability and slightly better ductility. | 170 | 240 | 2.5 | 85 HB | 29 % IACS |
Solution heat treated and artificially aged | Highest strength condition for AC4B; choose for loaded housings and pressure parts, accepting distortion risk and heat-treat cost. | 185 | 275 | 2 | 92 HB | 25 % IACS |
What is AC4B?
AC4B is a JIS Al-Si-Cu casting alloy (close to A319.0, ZL107 and 380.0) in which 2–4 % Cu raises strength and machinability over Al-Si-Mg grades. It is specified for gravity and sand castings that need good chip control and dimensional stability, typically cylinder heads, pump housings and compressor parts, with 110 MPa yield, 180 MPa tensile, 2 % elongation, 75 HB and 109 W/m·K. The copper lowers corrosion resistance (score 40) and makes fusion welding crack-prone, and service is limited to about 150 °C; choose AC4C where corrosion or ductility matters more than machinability (score 68). AC4B has a density of 2.79 g/cm³ (0.101 lb/in³), heavier than 77% of aluminum grades. It melts at 516°C (961 °F). AC4B has a yield strength of 110 MPa (16 ksi) and a tensile strength of 180 MPa (26.1 ksi) — weaker than 81% of aluminum grades. Elongation at break is 2% and the elastic modulus is 74 GPa (10.7 Msi).
What is AC4B used for?
- cylinder heads
- pump housings
- compressor parts
Limitations
- Hard to polish — 40/100, worse than 91% of aluminum grades
- Poor heat conductor — 109 W/m·K (63 BTU/hr·ft·°F), worse than 90% of aluminum grades
- Limited ductility — 2%, worse than 87% of aluminum grades
- Low electrical conductivity — 27 % IACS, worse than 86% of aluminum grades
- Low strength — 110 MPa (16 ksi), worse than 81% of aluminum grades
AC4B properties
Typical room-temperature values for AC4B-F; bars are the position among aluminum grades.
Physical3
AC4B has a density of 2.79 g/cm³ (0.101 lb/in³), heavier than 77% of aluminum grades. It melts at 516°C (961 °F).
Mechanical12
AC4B has a yield strength of 110 MPa (16 ksi) and a tensile strength of 180 MPa (26.1 ksi) — weaker than 81% of aluminum grades. Elongation at break is 2% and the elastic modulus is 74 GPa (10.7 Msi).
Thermal6
AC4B is rated for continuous service to 150°C (302 °F). It conducts heat at 109 W/m·K (63 BTU/hr·ft·°F), worse than 90% of aluminum grades. Thermal expansion is 21.5 µm/m·K (11.9 µin/in·°F).
Electrical3
AC4B conducts electricity at 27 % IACS, worse than 86% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is fair (40/100), worse than 75% of aluminum grades.
Sustainability4
Producing a kilogram of AC4B takes about 150 MJ of energy and emits 11.5 kg of CO₂ — less than 97% of aluminum grades. Typical recycled content is 85%.
Manufacturability6
AC4B's machinability is good (68/100, better than 67% of aluminum grades); weldability fair (45/100).
Common Calculations5
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 aluminum family
Yield strength against density for every aluminum grade FabDigit runs. AC4B is highlighted; hover a dot for its name, or open the interactive family chart.
Working with AC4B
Is AC4B easy to machine?
Machines well with sharp PCD or polished-carbide tools and flood coolant; Si particles are abrasive so PCD is preferred for volume work, and chips are short and easy to clear.
Can AC4B be welded?
TIG/MIG repair possible with 4043/4047 filler but the 2–4 % Cu gives real hot-cracking and porosity risk; preheat 150–200 °C and re-solution/age if T6 properties are required.
Can AC4B be formed, bent or molded?
Foundry alloy only — excellent fluidity and feeding for sand, gravity and low-pressure permanent-mold casting; use Sr/Na modification and Ti-B refinement, and degas well since Cu-Si melts pick up hydrogen readily.
AC4B 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 |
|---|---|---|
| SiJIS H5202 AC4B | 7 – 10 | 8.5 |
| Cu | 2 – 4 | 3 |
| Mg | ≤ 0.5 | 0.2 |
| Zn | ≤ 1 | 0.3 |
| Fehigher Fe embrittles; keep low for T6 | ≤ 1 | 0.6 |
| Mn | ≤ 0.5 | 0.2 |
| Ni | ≤ 0.35 | |
| Tigrain refiner | ≤ 0.2 | 0.1 |
| Sn | ≤ 0.1 | |
| Pb | ≤ 0.1 | |
| Al | balance |
What surface finishes work on AC4B?
Decorative anodizing is not viable (dark, mottled film); use chromate/trivalent conversion coating, powder coat or paint, and impregnate for pressure tightness on porous sections.
Surface treatments FabDigit runs on aluminum parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Equivalent designations
Standards and trade names that resolve to Aluminum AC4B in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Similar grades
- A319.0ZL107380.0
How much does AC4B cost?
AC4B is a standard-cost aluminum ($$), cheaper than about 71% 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.
AC4B — frequently asked
What is AC4B used for?
AC4B is typically used for cylinder heads, pump housings and compressor parts. In short: best machinability in family; cu-strengthened, lower corrosion resistance; economical gravity-cast alloy.
What is the yield strength of AC4B?
AC4B has a typical yield strength of 110 MPa (16 ksi) and a tensile strength of 180 MPa (26.1 ksi) — weaker than 81% of aluminum grades. Strength varies by condition: see the 4 listed tempers.
Is AC4B easy to machine?
Reasonably — machinability is rated good (68/100, better than 67% of aluminum grades). Machines well with sharp PCD or polished-carbide tools and flood coolant; Si particles are abrasive so PCD is preferred for volume work, and chips are short and easy to clear.
Can AC4B be welded?
With care — weldability is rated fair (45/100). TIG/MIG repair possible with 4043/4047 filler but the 2–4 % Cu gives real hot-cracking and porosity risk; preheat 150–200 °C and re-solution/age if T6 properties are required.
What surface finishes work on AC4B?
Decorative anodizing is not viable (dark, mottled film); use chromate/trivalent conversion coating, powder coat or paint, and impregnate for pressure tightness on porous sections.
Can AC4B be formed, bent or molded?
Foundry alloy only — excellent fluidity and feeding for sand, gravity and low-pressure permanent-mold casting; use Sr/Na modification and Ti-B refinement, and degas well since Cu-Si melts pick up hydrogen readily.
What is the maximum service temperature of AC4B?
AC4B is rated for continuous use to about 150°C (302 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between AC4B-F and AC4B-T6?
F is the default condition — default and cheapest condition; use where moderate strength and good dimensional stability after machining are enough. T6: highest strength condition for AC4B; choose for loaded housings and pressure parts, accepting distortion risk and heat-treat cost. Yield strength is 110 MPa in F versus 185 MPa in T6.
How much does AC4B cost?
AC4B is a standard-cost aluminum ($$), cheaper than about 71% 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
- JIS H 5202 Aluminium alloy castings — JSA (2010)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys (319.0/B319.0) — ASM International (1990)
- ASTM B26/B26M and Aluminum Association Pink Sheets (casting alloy registration) — ASTM / Aluminum Association (2018)
- GB/T 1173 (ZL107) — SAC (2013)
- ASM Handbook Vol.13B — Corrosion of Aluminum Alloys — ASM International (2005)
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.