Aluminum 443
AA 443 · UNS A04430 · EN AlSi5 · BS LM18 · also S5C
443 (443.0, formerly alloy 43; close to AlSi5, also listed as A04430 / S5C with B443 and C443 variants) is a non-heat-treatable aluminium-silicon casting alloy with about 5 % Si, giving high fluidity, low hot-tearing tendency, pressure tightness and good corrosion resistance.
443 tempers and conditions
443 is supplied in 6 conditions, soft to hard.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
B443.0-F | Choose when maximum corrosion resistance and anodic/chemical-finish quality are needed; copper held to 0.15 % max. | 41 | 117 | 6 | 35 HB | 39 % IACS |
As fabricated | Standard supply condition for sand castings; alloy is not heat-treatable, so F covers virtually all commercial 443 parts. | 55 | 130 | 8 | 40 HB | 37 % IACS |
Cooled from hot working and artificially aged | Nominal T5 on 443: ageing straight from the casting heat gives no precipitation strengthening in this Mg- and Cu-free Al-5Si alloy, so it acts mainly as a dimensional stress-relief and properties stay close to as-cast F. | 60 | 135 | 7 | 42 HB | 38 % IACS |
F | Pick for permanent-mold parts needing somewhat higher strength and ductility than sand casting from faster solidification. | 62 | 159 | 10 | 45 HB | 37 % IACS |
Solution heat treated and artificially aged | Nominal T6 on 443: with essentially no Mg or Cu the alloy is not precipitation hardenable, so solution treating and ageing only spheroidises the eutectic silicon — strength rises marginally over F and the temper is rarely specified commercially. | 70 | 150 | 6 | 45 HB | 38 % IACS |
C443.0-F | Die-casting version of the alloy: highest strength and hardness of the 443 family, chosen for thin-wall pressure die castings needing ductility and corrosion resistance. | 110 | 228 | 9 | 65 HB | 37 % IACS |
What is 443?
443 (443.0, formerly alloy 43; close to AlSi5, also listed as A04430 / S5C with B443 and C443 variants) is a non-heat-treatable aluminium-silicon casting alloy with about 5 % Si, giving high fluidity, low hot-tearing tendency, pressure tightness and good corrosion resistance. It suits thin-wall, complex sand, permanent-mould and pressure die castings (C443.0) that must resist seawater or be anodised for weathering. Strength is low — around 130 MPa tensile as sand cast — and with no Mg or Cu it cannot be precipitation hardened, so it is supplied as F; it cuts gummy and silicon turns clear anodising grey. Use 356 when T6 strength is needed. 443 has a density of 2.69 g/cm³ (0.0972 lb/in³), lighter than 67% of aluminum grades. It melts at 577°C (1,071 °F). 443 has a yield strength of 55 MPa (7.98 ksi) and a tensile strength of 130 MPa (18.9 ksi) — weaker than 94% of aluminum grades. Elongation at break is 8% and the elastic modulus is 71 GPa (10.3 Msi).
What is 443 used for?
- Decorative castings
- Hardware and fittings
- Thin-wall complex sand castings
- Marine fittings exposed to seawater
- Pressure-tight housings and covers
- Die-cast enclosures (C443.0)
- Architectural trim castings
Advantages
- High service temperature — 200°C (392 °F), better than 90% of aluminum grades
- Readily welded — 85/100, better than 79% of aluminum grades
Limitations
- Low strength — 55 MPa (7.98 ksi), worse than 94% of aluminum grades
- Low fracture toughness — 17 MPa·√m (15.5 ksi·√in), worse than 83% of aluminum grades
- Hard to polish — 45/100, worse than 76% of aluminum grades
443 properties
Typical room-temperature values; bars are the position among aluminum grades.
Physical3
443 has a density of 2.69 g/cm³ (0.0972 lb/in³), lighter than 67% of aluminum grades. It melts at 577°C (1,071 °F).
Mechanical11
443 has a yield strength of 55 MPa (7.98 ksi) and a tensile strength of 130 MPa (18.9 ksi) — weaker than 94% of aluminum grades. Elongation at break is 8% and the elastic modulus is 71 GPa (10.3 Msi).
Thermal6
443 is rated for continuous service to 200°C (392 °F). It conducts heat at 142 W/m·K (82 BTU/hr·ft·°F), better than 51% of aluminum grades. Thermal expansion is 22.1 µm/m·K (12.3 µin/in·°F).
Electrical3
443 conducts electricity at 37 % IACS, better than 58% of aluminum grades.
Chemical & Environmental3
Corrosion resistance is good (58/100), better than 57% of aluminum grades.
Sustainability4
Producing a kilogram of 443 takes about 200 MJ of energy and emits 12 kg of CO₂ — less than 60% of aluminum grades. Typical recycled content is 70%.
Manufacturability6
443's machinability is fair (45/100, worse than 72% of aluminum grades); weldability excellent (85/100).
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. 443 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 443
Is 443 easy to machine?
Soft and gummy — use sharp polished-flute carbide, high speed, generous rake and flood lubricant to avoid built-up edge and torn surfaces.
Can 443 be welded?
Very good weldability by GTAW/GMAW with 4043 or 4047 filler; no post-weld heat treatment can restore strength since the alloy is non-heat-treatable.
Can 443 be formed, bent or molded?
Excellent fluidity and low hot-tear tendency for sand, permanent-mold and (as C443.0) pressure die casting; not a wrought alloy — no cold forming.
Manufacturability
The process limits FabDigit applies to 443. Every 443 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Better45 / 100 |
|---|---|
| ISO material group | N.1 |
| Cutting speed (rough / finish) | 350 / 420 m/min |
| Minimum wall | 0.5 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 8× diameter |
| Best surface (machined / polished) | Ra 0.8 / — |
| Hardenable after machining | No |
443 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 |
|---|---|---|
| Si443.0 per ASTM B26/B108 | 4.5 – 6 | 5.25 |
| Fe2.0 max in C443.0 die-casting variant | ≤ 0.8 | |
| Cu0.15 max in B443.0; 0.30 max in A443.0 | ≤ 0.6 | |
| Mn0.35 max in C443.0 | ≤ 0.5 | |
| Mgkept low — alloy is intentionally non-heat-treatable | ≤ 0.05 | |
| Zn | ≤ 0.5 | |
| Ti | ≤ 0.25 | |
| NiC443.0 only | ≤ 0.5 | |
| Others (each)total 0.15 max | ≤ 0.05 | |
| Al | balance |
What surface finishes work on 443?
Takes chemical conversion coating and paint well; hard anodize is protective but decorative clear anodize turns grey due to silicon; polishing limited by eutectic Si.
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).
Passivation
Conversion Coating
PVD Coating
Equivalent designations
Standards and trade names that resolve to Aluminum 443 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- A04430
- EN / DIN / Werkstoff-Nr.
- AlSi5
- BS
- LM18
- Trade names
- S5C
- Also called
- S5B
How much does 443 cost?
443 is a budget-cost aluminum ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
443 — frequently asked
What is 443 used for?
443 is typically used for decorative castings, hardware and fittings, thin-wall complex sand castings, marine fittings exposed to seawater, pressure-tight housings and covers and die-cast enclosures (C443.0). In short: low-strength cast Al-Si.
What is the yield strength of 443?
443 has a typical yield strength of 55 MPa (7.98 ksi) and a tensile strength of 130 MPa (18.9 ksi) — weaker than 94% of aluminum grades. Strength varies by condition: see the 6 listed tempers.
Is 443 easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 72% of aluminum grades). Soft and gummy — use sharp polished-flute carbide, high speed, generous rake and flood lubricant to avoid built-up edge and torn surfaces.
Can 443 be welded?
Yes — weldability is rated excellent (85/100). Very good weldability by GTAW/GMAW with 4043 or 4047 filler; no post-weld heat treatment can restore strength since the alloy is non-heat-treatable.
What surface finishes work on 443?
Takes chemical conversion coating and paint well; hard anodize is protective but decorative clear anodize turns grey due to silicon; polishing limited by eutectic Si.
Can 443 be formed, bent or molded?
Excellent fluidity and low hot-tear tendency for sand, permanent-mold and (as C443.0) pressure die casting; not a wrought alloy — no cold forming.
What is the maximum service temperature of 443?
443 is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does 443 cost?
443 is a budget-cost aluminum ($), cheaper than about 90% 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.
Can FabDigit make parts in 443?
Yes — 443 is available for CNC machining; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM B26/B26M — Aluminum-Alloy Sand Castings — ASTM International (2018)
- ASTM B108/B108M — Aluminum-Alloy Permanent Mold Castings — ASTM International (2019)
- ASTM B85/B85M — Aluminum-Alloy Die Castings — ASTM International (2018)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys — ASM International (1990)
- Aluminum Association Designations and Chemical Composition Limits for Aluminum Alloys in the Form of Castings and Ingot (Pink Sheets) — The Aluminum Association (2018)
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.