Precious Metal Dental Gold Type IV Hard
Supply condition · default condition
ASTM ADA Spec No.5 Type IV · ISO 1562 Type 4
Hard = age/order hardened
Standard delivery condition for partial denture frameworks and thin high-stress castings needing maximum proof stress and hardness.
Values for the Hard 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 |
Spheroidize annealed | Condition of a casting devested without extra heat treatment; partially ordered, intermediate strength and ductility. | 420 | 560 | 15 | 195 HB | 12 % IACS |
HardDefaultThis page 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 Hard?
Dental Gold Type IV Hard is Dental Gold Type IV supplied in the Hard condition — standard delivery condition for partial denture frameworks and thin high-stress castings needing maximum proof stress and hardness. Dental Gold Type IV Hard has a yield strength of 570 MPa (82.7 ksi) and a tensile strength of 750 MPa (109 ksi) — stronger than 97% of precious metal grades. Elongation at break is 6% and the elastic modulus is 95 GPa (13.8 Msi). Dental Gold Type IV Hard 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).
Advantages
- High strength — 570 MPa (82.7 ksi), better than 97% of precious metal grades
- Easy to machine — 55/100, better than 86% of precious metal grades
- Polishes to a fine finish — 95/100, better than 86% of precious metal grades
Limitations
- Limited formability — 30/100, worse than 94% of precious metal grades
- Limited ductility — 6%, worse than 93% of precious metal grades
- Heavy — 15.5 g/cm³ (0.56 lb/in³), worse than 77% of precious metal grades
Dental Gold Type IV Hard properties
Typical room-temperature values for Dental Gold Type IV Hard; 23 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 Hard 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 Hard has a yield strength of 570 MPa (82.7 ksi) and a tensile strength of 750 MPa (109 ksi) — stronger than 97% of precious metal grades. Elongation at break is 6% and the elastic modulus is 95 GPa (13.8 Msi).
Thermal6
Dental Gold Type IV Hard is rated for continuous service to 250°C (482 °F). It conducts heat at 62 W/m·K (35.8 BTU/hr·ft·°F), worse than 69% of precious metal grades. Thermal expansion is 14.5 µm/m·K (8.06 µin/in·°F).
Electrical3
Dental Gold Type IV Hard conducts electricity at 15 % IACS, worse than 65% of precious metal grades.
Chemical & Environmental3
Corrosion resistance is excellent (90/100), better than 69% of precious metal grades.
Sustainability3
Producing a kilogram of Dental Gold Type IV Hard 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 Hard's machinability is good (55/100, better than 86% of precious metal grades); weldability good (60/100); formability poor (30/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Dental Gold Type IV Hard
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 Hard — frequently asked
What is Dental Gold Type IV Hard used for?
Dental Gold Type IV Hard 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 Hard?
Dental Gold Type IV Hard has a typical yield strength of 570 MPa (82.7 ksi) and a tensile strength of 750 MPa (109 ksi) — stronger than 97% of precious metal grades. Strength varies by condition: see the 3 listed tempers.
Is Dental Gold Type IV Hard easy to machine?
Reasonably — machinability is rated good (55/100, better than 86% 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 Hard be welded?
Yes — weldability is rated good (60/100). 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 Hard?
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 Hard 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 Hard?
Dental Gold Type IV Hard is rated for continuous use to about 250°C (482 °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.