Precious Metal 85Pt-15Ir-O (Annealed)
Temper · default condition
Choose for wire drawing, coiling, deep forming, electrode fabrication and welded assemblies where maximum ductility is needed.
Values for the O condition
Other 85Pt-15Ir tempers and conditions
85Pt-15Ir is listed in 3 conditions; see the grade overview at 85Pt-15Ir.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ODefaultThis page Annealed | Choose for wire drawing, coiling, deep forming, electrode fabrication and welded assemblies where maximum ductility is needed. | 200 | 480 | 27 | 84 HRB | 6.2 % IACS |
Half hard | Compromise temper for contact rivets, blanked contact discs and light spring members that still need some bend ductility. | 500 | 700 | 8 | 20 HRC | 6 % IACS |
Hardened | Choose for slip-ring brushes, potentiometer wiper wire, spring contacts and probe tips needing maximum hardness and wear life. | 800 | 965 | 3 | 28 HRC | 5.4 % IACS |
What is 85Pt-15Ir-O?
85Pt-15Ir-O is 85Pt-15Ir in the O temper — choose for wire drawing, coiling, deep forming, electrode fabrication and welded assemblies where maximum ductility is needed. 85Pt-15Ir-O has a yield strength of 200 MPa (29 ksi) and a tensile strength of 480 MPa (69.6 ksi) — stronger than 51% of precious metal grades. Elongation at break is 27% and the elastic modulus is 205 GPa (29.7 Msi). 85Pt-15Ir-O has a density of 21.6 g/cm³ (0.78 lb/in³), heavier than 100% of precious metal grades. It melts at 1,790°C (3,254 °F).
Advantages
- Stiff — 205 GPa (29.7 Msi), better than 98% of precious metal grades
- Good corrosion resistance — 100/100, better than 98% of precious metal grades
- High service temperature — 1,000°C (1,832 °F), better than 95% of precious metal grades
Limitations
- Heavy — 21.6 g/cm³ (0.78 lb/in³), worse than 100% of precious metal grades
- High embodied carbon — 16,000 kg CO₂/kg, worse than 96% of precious metal grades
- Poor heat conductor — 26 W/m·K (15 BTU/hr·ft·°F), worse than 95% of precious metal grades
- Difficult to machine — 25/100, worse than 94% of precious metal grades
- Low electrical conductivity — 6.2 % IACS, worse than 91% of precious metal grades
85Pt-15Ir-O properties
Typical room-temperature values for 85Pt-15Ir-O; 17 are specific to this condition. Other listed values are 85Pt-15Ir reference data and may not represent this condition. Bars are the position among precious metal grades.
Physical3
85Pt-15Ir-O has a density of 21.6 g/cm³ (0.78 lb/in³), heavier than 100% of precious metal grades. It melts at 1,790°C (3,254 °F).
Mechanical11
85Pt-15Ir-O has a yield strength of 200 MPa (29 ksi) and a tensile strength of 480 MPa (69.6 ksi) — stronger than 51% of precious metal grades. Elongation at break is 27% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
85Pt-15Ir-O is rated for continuous service to 1,000°C (1,832 °F). It conducts heat at 26 W/m·K (15 BTU/hr·ft·°F), worse than 95% of precious metal grades. Thermal expansion is 8.6 µm/m·K (4.78 µin/in·°F).
Electrical3
85Pt-15Ir-O conducts electricity at 6.2 % IACS, worse than 91% of precious metal grades.
Chemical & Environmental3
Corrosion resistance is excellent (100/100), better than 98% of precious metal grades.
Sustainability4
Producing a kilogram of 85Pt-15Ir-O takes about 260,000 MJ of energy and emits 16,000 kg of CO₂ — more than 98% of precious metal grades. Typical recycled content is 40%.
Manufacturability8
85Pt-15Ir-O's machinability is poor (25/100, worse than 94% of precious metal grades); weldability very good (70/100); formability very good (70/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 85Pt-15Ir-O
Is 85Pt-15Ir easy to machine?
Machines like a gummy, rapidly work-hardening noble alloy — sharp carbide or diamond tooling, low speed, heavy positive rake, continuous flood coolant, and always collect the chips as refinable scrap.
Can 85Pt-15Ir be welded?
Excellent for resistance, micro-TIG and laser welding to itself, Pt and PtIr electrodes; avoid contact with molten base metals (Fe, Ni, Cu) which embrittle the joint.
Can 85Pt-15Ir be formed, bent or molded?
Anneal at 900–1100 °C in air or clean atmosphere between drawing/rolling passes; annealed material draws to fine wire readily, hard temper needs generous bend radii.
What surface finishes work on 85Pt-15Ir?
No plating or anodising required — electropolish or mechanically polish to a mirror surface; the alloy will not tarnish, so contact resistance stays stable without any coating.
85Pt-15Ir 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 |
|---|---|---|
| Irsolid-solution hardener | 14.5 – 15.5 | 15 |
| Other (Pd+Rh+Ru+Au+base metals, total)impurity total for contact/electrode quality material | ≤ 0.15 | 0.05 |
| Ptbalance, 99.95 % pure base metal | ≥ 84.4 (balance) | — |
85Pt-15Ir-O — frequently asked
What is 85Pt-15Ir-O used for?
85Pt-15Ir-O is typically used for precision instrument contacts, slip rings and spark igniter electrodes. In short: hardest common Pt-Ir grade; tarnish-free to 1000 °C; very low electrical conductivity.
What is the yield strength of 85Pt-15Ir-O?
85Pt-15Ir-O has a typical yield strength of 200 MPa (29 ksi) and a tensile strength of 480 MPa (69.6 ksi) — stronger than 51% of precious metal grades. Strength varies by condition: see the 3 listed tempers.
Is 85Pt-15Ir-O easy to machine?
Not especially — machinability is rated poor (25/100, worse than 94% of precious metal grades). Machines like a gummy, rapidly work-hardening noble alloy — sharp carbide or diamond tooling, low speed, heavy positive rake, continuous flood coolant, and always collect the chips as refinable scrap.
Can 85Pt-15Ir-O be welded?
Yes — weldability is rated very good (70/100). Excellent for resistance, micro-TIG and laser welding to itself, Pt and PtIr electrodes; avoid contact with molten base metals (Fe, Ni, Cu) which embrittle the joint.
What surface finishes work on 85Pt-15Ir-O?
No plating or anodising required — electropolish or mechanically polish to a mirror surface; the alloy will not tarnish, so contact resistance stays stable without any coating.
Can 85Pt-15Ir-O be formed, bent or molded?
Anneal at 900–1100 °C in air or clean atmosphere between drawing/rolling passes; annealed material draws to fine wire readily, hard temper needs generous bend radii.
What is the maximum service temperature of 85Pt-15Ir-O?
85Pt-15Ir-O is rated for continuous use to about 1,000°C (1,832 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 85Pt-15Ir-O and 85Pt-15Ir-H?
O is the default condition — choose for wire drawing, coiling, deep forming, electrode fabrication and welded assemblies where maximum ductility is needed. H: choose for slip-ring brushes, potentiometer wiper wire, spring contacts and probe tips needing maximum hardness and wear life. Yield strength is 200 MPa in O versus 800 MPa in H.
Sources
- ASTM B684 — Platinum-Iridium Electrical Contact Material — ASTM International (2020)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (Precious Metals) — ASM International (1990)
- Platinum-Iridium Alloy Technical Data (Pt-10Ir / Pt-15Ir / Pt-20Ir) — Johnson Matthey Noble Metals (2021)
- Precious Metal Alloys for Electrical Contacts and Medical Electrodes — Heraeus (2022)
- Platinum Metals Review — physical properties of Pt-Ir solid solutions — Johnson Matthey (2014)
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.