Precious Metal Dental Gold Type III Hard
Supply condition
ASTM ADA Spec No.5 Type III · ISO 1562 Type 3
Hard = hardened
Pick for final delivery of high-stress crowns, bridge retainers and clasps where maximum proof strength and wear resistance are wanted.
Values for the Hard condition
Other Dental Gold Type III tempers and conditions
Dental Gold Type III is listed in 3 conditions; see the grade overview at Dental Gold Type III.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
SOFTDefault Softened | Pick for maximum ductility and burnishability during margin adaptation, soldering and try-in; the condition against which ISO 1562 Type 3 properties are specified. | 250 | 420 | 30 | 125 HB | — |
bench-cooled casting | Condition straight out of the investment mould without post-casting heat treatment; partially ordered, intermediate strength. | 280 | 460 | 22 | 138 HB | 15 % IACS |
HardThis page Hardened | Pick for final delivery of high-stress crowns, bridge retainers and clasps where maximum proof strength and wear resistance are wanted. | 400 | 550 | 10 | 180 HB | — |
What is Dental Gold Type III Hard?
Dental Gold Type III Hard is Dental Gold Type III supplied in the Hard condition — pick for final delivery of high-stress crowns, bridge retainers and clasps where maximum proof strength and wear resistance are wanted. Dental Gold Type III Hard has a yield strength of 400 MPa (58 ksi) and a tensile strength of 550 MPa (79.8 ksi) — stronger than 96% of precious metal grades. Elongation at break is 10% and the elastic modulus is 98 GPa (14.2 Msi). Dental Gold Type III Hard has a density of 15.6 g/cm³ (0.564 lb/in³), heavier than 79% of precious metal grades. It melts at 890°C (1,634 °F). SOFT is the default condition FabDigit quotes; Hard is available on request or by drawing note.
Advantages
- Easy to machine — 70/100, better than 101% of precious metal grades
- Polishes to a fine finish — 98/100, better than 98% of precious metal grades
- High strength — 400 MPa (58 ksi), better than 96% of precious metal grades
- Good corrosion resistance — 97/100, better than 88% of precious metal grades
- Readily welded — 75/100, better than 78% of precious metal grades
Limitations
- Limited ductility — 10%, worse than 89% of precious metal grades
- Limited formability — 55/100, worse than 89% of precious metal grades
- High embodied carbon — 13,000 kg CO₂/kg, worse than 81% of precious metal grades
- Heavy — 15.6 g/cm³ (0.564 lb/in³), worse than 79% 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 III Hard properties
Typical room-temperature values for Dental Gold Type III Hard; 10 are specific to this condition. Other listed values are Dental Gold Type III reference data and may not represent this condition. Bars are the position among precious metal grades.
Physical3
Dental Gold Type III Hard has a density of 15.6 g/cm³ (0.564 lb/in³), heavier than 79% of precious metal grades. It melts at 890°C (1,634 °F).
Mechanical9
Dental Gold Type III Hard has a yield strength of 400 MPa (58 ksi) and a tensile strength of 550 MPa (79.8 ksi) — stronger than 96% of precious metal grades. Elongation at break is 10% and the elastic modulus is 98 GPa (14.2 Msi).
Thermal6
Dental Gold Type III Hard is rated for continuous service to 350°C (662 °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 III Hard conducts electricity at 15 % IACS, worse than 65% of precious metal grades.
Chemical & Environmental3
Corrosion resistance is excellent (97/100), better than 88% of precious metal grades.
Sustainability4
Producing a kilogram of Dental Gold Type III Hard takes about 180,000 MJ of energy and emits 13,000 kg of CO₂ — more than 77% of precious metal grades. Typical recycled content is 60%.
Manufacturability7
Dental Gold Type III Hard's machinability is very good (70/100, better than 101% of precious metal grades); weldability very good (75/100); formability good (55/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Dental Gold Type III Hard
Is Dental Gold Type III easy to machine?
Very soft and gummy — use sharp carbide/HSS tools, high speed, light feed and generous lubrication; hardened condition machines and finishes more cleanly, and all swarf must be collected for refining.
Can Dental Gold Type III be welded?
Laser and pulse-arc (PDL) welding are routine; gas torch work is possible but reheating above ~500 °C dissolves the ordered phase, so hardened parts must be re-aged afterwards.
Can Dental Gold Type III be formed, bent or molded?
Designed for lost-wax centrifugal or vacuum-pressure casting at ~1000–1050 °C into gypsum-bonded investment; in the softened state margins can be burnished and clasps adjusted cold.
What surface finishes work on Dental Gold Type III?
Polishes to a permanent mirror lustre with rouge/tripoli; no anodizing or passivation needed, and electroplated gold flashing is only cosmetic.
Dental Gold Type III 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 |
|---|---|---|
| AuADA No.5 Type III: gold ≥65 %, noble (Au+Pt group) ≥75 % | 65 – 78 | 72 |
| Agsolid-solution / colour control | 5 – 18 | 12 |
| Cuprovides AuCu order hardening | 6 – 14 | 9.5 |
| Pdraises melting range and tarnish resistance | 0 – 5 | 2 |
| Pt | 0 – 4 | 1.5 |
| Zndeoxidiser, improves castability | 0 – 2 | 1.2 |
| Irgrain refiner (also Ru/Re) | 0 – 0.1 | 0.01 |
| In+Sn+other | 0 – 1 | 0.3 |
Dental Gold Type III Hard — frequently asked
What is Dental Gold Type III Hard used for?
Dental Gold Type III Hard is typically used for crowns, bridges, high-stress restorations and onlays. In short: age-hardenable dental gold; standard crown-and-bridge alloy; harder than Type II.
What is the yield strength of Dental Gold Type III Hard?
Dental Gold Type III Hard has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 550 MPa (79.8 ksi) — stronger than 96% of precious metal grades. Strength varies by condition: see the 3 listed tempers.
Is Dental Gold Type III Hard easy to machine?
Yes — machinability is rated very good (70/100, better than 101% of precious metal grades). Very soft and gummy — use sharp carbide/HSS tools, high speed, light feed and generous lubrication; hardened condition machines and finishes more cleanly, and all swarf must be collected for refining.
Can Dental Gold Type III Hard be welded?
Yes — weldability is rated very good (75/100). Laser and pulse-arc (PDL) welding are routine; gas torch work is possible but reheating above ~500 °C dissolves the ordered phase, so hardened parts must be re-aged afterwards.
What surface finishes work on Dental Gold Type III Hard?
Polishes to a permanent mirror lustre with rouge/tripoli; no anodizing or passivation needed, and electroplated gold flashing is only cosmetic.
Can Dental Gold Type III Hard be formed, bent or molded?
Designed for lost-wax centrifugal or vacuum-pressure casting at ~1000–1050 °C into gypsum-bonded investment; in the softened state margins can be burnished and clasps adjusted cold.
What is the maximum service temperature of Dental Gold Type III Hard?
Dental Gold Type III Hard is rated for continuous use to about 350°C (662 °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 III SOFT and Dental Gold Type III Hard?
SOFT is the default condition — pick for maximum ductility and burnishability during margin adaptation, soldering and try-in; the condition against which ISO 1562 Type 3 properties are specified. Hard: pick for final delivery of high-stress crowns, bridge retainers and clasps where maximum proof strength and wear resistance are wanted. Yield strength is 250 MPa in SOFT versus 400 MPa in Hard.
Sources
- ISO 1562 Dentistry — Casting gold alloys — ISO (2004)
- ANSI/ADA Specification No. 5 — Dental Casting Alloys — American Dental Association (2018)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys (precious metals) — ASM International (1990)
- Craig's Restorative Dental Materials — Elsevier (2019)
- Dental casting gold alloy technical data (type III hard) — precious-metal dental alloy producers (2023)
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.