Precious Metal Dental Gold Type IV-AC (Spheroidize annealed)
Heat-treated state
ASTM ADA Spec No.5 Type IV · ISO 1562 Type 4
Condition of a casting devested without extra heat treatment; partially ordered, intermediate strength and ductility.
Values for the AC condition
Other Dental Gold Type IV tempers and conditions
Dental Gold Type IV is listed in 3 conditions; see the grade overview at Dental Gold Type IV.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Softened | Choose when clasps or margins must be adjusted, burnished or soldered before final hardening. | 360 | 490 | 25 | 172 HB | 13 % IACS |
ACThis page Spheroidize annealed | Condition of a casting devested without extra heat treatment; partially ordered, intermediate strength and ductility. | 420 | 560 | 15 | 195 HB | 12 % IACS |
HardDefault Age/order hardened | Standard delivery condition for partial denture frameworks and thin high-stress castings needing maximum proof stress and hardness. | 570 | 750 | 6 | 22 HRC | 15 % IACS |
What is Dental Gold Type IV-AC?
Dental Gold Type IV-AC is Dental Gold Type IV heat treated to AC — condition of a casting devested without extra heat treatment; partially ordered, intermediate strength and ductility. Dental Gold Type IV-AC has a yield strength of 420 MPa (60.9 ksi) and a tensile strength of 560 MPa (81.2 ksi) — stronger than 96% of precious metal grades. Elongation at break is 15% and the elastic modulus is 92 GPa (13.3 Msi). Dental Gold Type IV-AC has a density of 15.5 g/cm³ (0.56 lb/in³), heavier than 77% of precious metal grades. It melts at 880°C (1,616 °F). Hard is the default condition FabDigit quotes; AC is available on request or by drawing note.
Advantages
- Easy to machine — 60/100, better than 97% of precious metal grades
- High strength — 420 MPa (60.9 ksi), better than 96% of precious metal grades
- Polishes to a fine finish — 95/100, better than 86% of precious metal grades
- Readily welded — 75/100, better than 78% of precious metal grades
Limitations
- Limited formability — 45/100, worse than 91% of precious metal grades
- Limited service temperature — 200°C (392 °F), worse than 89% of precious metal grades
- Limited ductility — 15%, worse than 86% of precious metal grades
- Heavy — 15.5 g/cm³ (0.56 lb/in³), worse than 77% of precious metal grades
- Poor heat conductor — 55 W/m·K (31.8 BTU/hr·ft·°F), worse than 76% of precious metal grades
Dental Gold Type IV-AC properties
Typical room-temperature values for Dental Gold Type IV-AC; 19 are specific to this condition. Other listed values are Dental Gold Type IV reference data and may not represent this condition. Bars are the position among precious metal grades.
Physical3
Dental Gold Type IV-AC has a density of 15.5 g/cm³ (0.56 lb/in³), heavier than 77% of precious metal grades. It melts at 880°C (1,616 °F).
Mechanical16
Dental Gold Type IV-AC has a yield strength of 420 MPa (60.9 ksi) and a tensile strength of 560 MPa (81.2 ksi) — stronger than 96% of precious metal grades. Elongation at break is 15% and the elastic modulus is 92 GPa (13.3 Msi).
Thermal6
Dental Gold Type IV-AC is rated for continuous service to 200°C (392 °F). It conducts heat at 55 W/m·K (31.8 BTU/hr·ft·°F), worse than 76% of precious metal grades. Thermal expansion is 14.5 µm/m·K (8.06 µin/in·°F).
Electrical3
Dental Gold Type IV-AC conducts electricity at 12 % IACS, worse than 74% of precious metal grades.
Chemical & Environmental3
Corrosion resistance is excellent (92/100), better than 73% of precious metal grades.
Sustainability3
Producing a kilogram of Dental Gold Type IV-AC takes about 140,000 MJ of energy and emits 8,500 kg of CO₂ — more than 71% of precious metal grades. Typical recycled content is 60%.
Manufacturability8
Dental Gold Type IV-AC's machinability is good (60/100, better than 97% of precious metal grades); weldability very good (75/100); formability fair (45/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Dental Gold Type IV-AC
Is Dental Gold Type IV easy to machine?
Cuts easily but smears — use sharp carbide/HSS tools, light feeds and collect all swarf for refining.
Can Dental Gold Type IV be welded?
Laser and pulse-arc welded routinely in the softened state; gold solders (lower-melting) used for joining framework sections before hardening.
Can Dental Gold Type IV be formed, bent or molded?
Primarily lost-wax investment cast at ~1000 °C melt with gypsum-bonded investment; clasps can be bent only in the softened condition.
What surface finishes work on Dental Gold Type IV?
Excellent polishability to a mirror finish with rouge; not anodizable, electroplating or heat-tint colouring only if a different shade is required.
Dental Gold Type IV 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 |
|---|---|---|
| Auhigh-noble class; Au+Pt-group ≥ 75 % for ADA Type IV | 60 – 71 | 65 |
| Ag | 4 – 15 | 10 |
| Pdraises melting range and tarnish resistance | 0 – 5 | 3 |
| Ptgrain refinement and strength | 0 – 4 | 3 |
| Zndeoxidiser, improves casting fluidity | 0 – 2 | 1 |
| Irgrain refiner (trace) | 0 – 0.01 | 0.01 |
| Cuprovides AuCu ordering / age hardening | ≥ 9 (balance) | — |
Dental Gold Type IV-AC — frequently asked
What is Dental Gold Type IV-AC used for?
Dental Gold Type IV-AC is typically used for removable partial denture frameworks, clasps and thin high-stress castings. In short: hardest ADA dental gold; highest elastic limit; framework and clasp alloy.
What is the yield strength of Dental Gold Type IV-AC?
Dental Gold Type IV-AC has a typical yield strength of 420 MPa (60.9 ksi) and a tensile strength of 560 MPa (81.2 ksi) — stronger than 96% of precious metal grades. Strength varies by condition: see the 3 listed tempers.
Is Dental Gold Type IV-AC easy to machine?
Reasonably — machinability is rated good (60/100, better than 97% of precious metal grades). Cuts easily but smears — use sharp carbide/HSS tools, light feeds and collect all swarf for refining.
Can Dental Gold Type IV-AC be welded?
Yes — weldability is rated very good (75/100). Laser and pulse-arc welded routinely in the softened state; gold solders (lower-melting) used for joining framework sections before hardening.
What surface finishes work on Dental Gold Type IV-AC?
Excellent polishability to a mirror finish with rouge; not anodizable, electroplating or heat-tint colouring only if a different shade is required.
Can Dental Gold Type IV-AC be formed, bent or molded?
Primarily lost-wax investment cast at ~1000 °C melt with gypsum-bonded investment; clasps can be bent only in the softened condition.
What is the maximum service temperature of Dental Gold Type IV-AC?
Dental Gold Type IV-AC 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.
What is the difference between Dental Gold Type IV Hard and Dental Gold Type IV SOFT?
Hard is the default condition — standard delivery condition for partial denture frameworks and thin high-stress castings needing maximum proof stress and hardness. SOFT: choose when clasps or margins must be adjusted, burnished or soldered before final hardening. Yield strength is 570 MPa in Hard versus 360 MPa in SOFT.
Sources
- ISO 1562 Dentistry — Casting gold alloys — ISO (2004)
- ANSI/ADA Specification No.5 — Dental Casting Alloys — American Dental Association (2000)
- Phillips' Science of Dental Materials — Elsevier (2012)
- Craig's Restorative Dental Materials — Elsevier (2019)
- ASM Handbook Vol.2 — Properties of Precious Metals — ASM International (1990)
- Dental casting gold alloy datasheets (Type 4 / extra hard) — Ivoclar / Heraeus Kulzer / Jensen Dental (2020)
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.