Precious Metal Pt70Rh30/Pt94Rh6
ASTM E230 Type B
Pt70Rh30/Pt94Rh6 is the matched alloy pair — Pt-30Rh positive leg, Pt-6Rh negative leg — that forms the ASTM E230 Type B thermocouple, supplied as annealed or hard wire per leg (BP and BN) and as Class 1 or Class 2 matched pairs.
Reference datasheet — Pt70Rh30/Pt94Rh6 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the BP-Ann condition
Pt70Rh30/Pt94Rh6 tempers and conditions
Pt70Rh30/Pt94Rh6 is supplied in 4 conditions, soft to hard. BP-Ann is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
BN annealed | Standard supply condition of the negative leg; softer and denser than BP, drawn to the same diameter for a matched pair. | 120 | 255 | 35 | 78 HV | 10.1 % IACS |
BP-AnnDefault BP annealed | Standard supply condition of the positive leg; annealed for stable EMF and easy junction welding. | 250 | 550 | 28 | 125 HV | 9.1 % IACS |
BN hard-drawn | As-drawn negative leg for stiff, self-supporting elements; softens on first exposure to furnace temperature. | 520 | 620 | 3 | 162 HB | 9.9 % IACS |
BP hard-drawn | Choose when the wire must stay straight/self-supporting during assembly; anneal or first heating to service temperature restores EMF. | 900 | 1,050 | 3 | 25 HRC | 8.8 % IACS |
Supply forms, finishes and certifications
Ways Pt70Rh30/Pt94Rh6 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
PAIR-CL1 | Matched pair, IEC 60584-1 Class 1 / ASTM E230 special tolerance | Certification |
PAIR-CL2 | Matched pair, IEC 60584-1 Class 2 / ASTM E230 standard tolerance | Certification |
What is Pt70Rh30/Pt94Rh6?
Pt70Rh30/Pt94Rh6 is the matched alloy pair — Pt-30Rh positive leg, Pt-6Rh negative leg — that forms the ASTM E230 Type B thermocouple, supplied as annealed or hard wire per leg (BP and BN) and as Class 1 or Class 2 matched pairs. Because both legs are rhodium-alloyed platinum, the pair reads to about 1700 °C and is used without cold-junction compensation. Typical values are density 17.6 g/cm³, 250 MPa yield, 550 MPa tensile, 28 % elongation, 225 GPa modulus, 38 W/m·K and 9.1 % IACS. Output is low at low temperatures, machinability is 25 and metal cost is high; Type R or Type S suits work below about 1300 °C. Pt70Rh30/Pt94Rh6 has a density of 17.6 g/cm³ (0.636 lb/in³), heavier than 86% of precious metal grades. It melts at 1,900°C (3,452 °F). Pt70Rh30/Pt94Rh6 has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 550 MPa (79.8 ksi) — stronger than 81% of precious metal grades. Elongation at break is 28% and the elastic modulus is 225 GPa (32.6 Msi).
What is Pt70Rh30/Pt94Rh6 used for?
- Type B thermocouples
- Steelmaking temperature measurement
- Glass melting furnaces
Advantages
- High service temperature — 1,700°C (3,092 °F), better than 100% of precious metal grades
- Stiff — 225 GPa (32.6 Msi), better than 99% of precious metal grades
- Good corrosion resistance — 100/100, better than 98% of precious metal grades
- Readily welded — 85/100, better than 93% of precious metal grades
- High strength — 250 MPa (36.3 ksi), better than 81% of precious metal grades
Limitations
- High embodied carbon — 25,000 kg CO₂/kg, worse than 99% of precious metal grades
- Difficult to machine — 25/100, worse than 94% of precious metal grades
- Poor heat conductor — 38 W/m·K (22 BTU/hr·ft·°F), worse than 87% of precious metal grades
- Heavy — 17.6 g/cm³ (0.636 lb/in³), worse than 86% of precious metal grades
- Low electrical conductivity — 9.1 % IACS, worse than 82% of precious metal grades
Pt70Rh30/Pt94Rh6 properties
Typical room-temperature values for Pt70Rh30/Pt94Rh6-BP-Ann; bars are the position among precious metal grades.
Physical3
Pt70Rh30/Pt94Rh6 has a density of 17.6 g/cm³ (0.636 lb/in³), heavier than 86% of precious metal grades. It melts at 1,900°C (3,452 °F).
Mechanical9
Pt70Rh30/Pt94Rh6 has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 550 MPa (79.8 ksi) — stronger than 81% of precious metal grades. Elongation at break is 28% and the elastic modulus is 225 GPa (32.6 Msi).
Thermal6
Pt70Rh30/Pt94Rh6 is rated for continuous service to 1,700°C (3,092 °F). It conducts heat at 38 W/m·K (22 BTU/hr·ft·°F), worse than 87% of precious metal grades. Thermal expansion is 8.6 µm/m·K (4.78 µin/in·°F).
Electrical3
Pt70Rh30/Pt94Rh6 conducts electricity at 9.1 % IACS, worse than 82% of precious metal grades.
Chemical & Environmental3
Corrosion resistance is excellent (100/100), better than 98% of precious metal grades.
Sustainability4
Producing a kilogram of Pt70Rh30/Pt94Rh6 takes about 300,000 MJ of energy and emits 25,000 kg of CO₂ — more than 99% of precious metal grades. Typical recycled content is 55%.
Manufacturability8
Pt70Rh30/Pt94Rh6's machinability is poor (25/100, worse than 94% of precious metal grades); weldability excellent (85/100); formability very good (75/100).
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 precious metal family
Yield strength against density for every precious metal grade FabDigit runs. Pt70Rh30/Pt94Rh6 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Pt70Rh30/Pt94Rh6
Is Pt70Rh30/Pt94Rh6 easy to machine?
Essentially never machined — the alloys are gummy and smear; product is cold-drawn wire, foil or tube made by drawing/rolling with frequent 1000–1200 °C anneals.
Can Pt70Rh30/Pt94Rh6 be welded?
Junctions are made by butt/spot resistance welding or oxy-gas bead fusion of the two legs; use clean tooling only, never steel or copper contact at heat.
Can Pt70Rh30/Pt94Rh6 be formed, bent or molded?
Both legs draw readily to 0.05 mm with intermediate bright annealing; BN (Pt-6Rh) is markedly softer, so drawing schedules for a matched pair are set separately.
Pt70Rh30/Pt94Rh6 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 |
|---|---|---|
| Rhnegative leg BN (Pt94Rh6), supplied as a separate wire, Pt balance | 5.7 – 6.3 | 6 |
| Feimpurity limit, both legs | ≤ 0.01 | |
| Siimpurity limit — Si causes embrittlement | ≤ 0 | |
| Pdimpurity limit, both legs | ≤ 0.01 | |
| Ptbalance, 99.99 % base purity; total metallic impurities <0.01 % for thermocouple grade | balance |
What surface finishes work on Pt70Rh30/Pt94Rh6?
Supplied bright-annealed and used bare — no plating or coating; handle with clean gloves and protect with high-purity alumina insulators to avoid Si/C/P poisoning.
Equivalent designations
Standards and trade names that resolve to Precious Metal Pt70Rh30/Pt94Rh6 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ASTM
- E230 Type B
How much does Pt70Rh30/Pt94Rh6 cost?
Pt70Rh30/Pt94Rh6 is a high-cost precious metal ($$$$), pricier than about 78% 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.
Pt70Rh30/Pt94Rh6 — frequently asked
What is Pt70Rh30/Pt94Rh6 used for?
Pt70Rh30/Pt94Rh6 is typically used for type B thermocouples, steelmaking temperature measurement and glass melting furnaces. In short: highest-temperature thermocouple pair; no cold-junction compensation needed; rated to 1700 °C.
What is the yield strength of Pt70Rh30/Pt94Rh6?
Pt70Rh30/Pt94Rh6 has a typical yield strength of 250 MPa (36.3 ksi) and a tensile strength of 550 MPa (79.8 ksi) — stronger than 81% of precious metal grades. Strength varies by condition: see the 4 listed tempers.
Is Pt70Rh30/Pt94Rh6 easy to machine?
Not especially — machinability is rated poor (25/100, worse than 94% of precious metal grades). Essentially never machined — the alloys are gummy and smear; product is cold-drawn wire, foil or tube made by drawing/rolling with frequent 1000–1200 °C anneals.
Can Pt70Rh30/Pt94Rh6 be welded?
Yes — weldability is rated excellent (85/100). Junctions are made by butt/spot resistance welding or oxy-gas bead fusion of the two legs; use clean tooling only, never steel or copper contact at heat.
What surface finishes work on Pt70Rh30/Pt94Rh6?
Supplied bright-annealed and used bare — no plating or coating; handle with clean gloves and protect with high-purity alumina insulators to avoid Si/C/P poisoning.
Can Pt70Rh30/Pt94Rh6 be formed, bent or molded?
Both legs draw readily to 0.05 mm with intermediate bright annealing; BN (Pt-6Rh) is markedly softer, so drawing schedules for a matched pair are set separately.
What is the maximum service temperature of Pt70Rh30/Pt94Rh6?
Pt70Rh30/Pt94Rh6 is rated for continuous use to about 1,700°C (3,092 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Pt70Rh30/Pt94Rh6 BP-Ann and Pt70Rh30/Pt94Rh6 BP-Hard?
BP-Ann is the default condition — standard supply condition of the positive leg; annealed for stable EMF and easy junction welding. BP-Hard: choose when the wire must stay straight/self-supporting during assembly; anneal or first heating to service temperature restores EMF. Yield strength is 250 MPa in BP-Ann versus 900 MPa in BP-Hard.
How much does Pt70Rh30/Pt94Rh6 cost?
Pt70Rh30/Pt94Rh6 is a high-cost precious metal ($$$$), pricier than about 78% 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.
Sources
- IEC 60584-1 Thermocouples — Part 1: EMF specifications and tolerances — IEC (2013)
- ASTM E230/E230M Standard Specification for Temperature-EMF Tables for Standardized Thermocouples — ASTM International (2017)
- Platinum-rhodium alloys for thermocouples and high-temperature applications — Johnson Matthey / Heraeus (2021)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials (precious metals) — ASM International (1990)
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.