Nickel Alloy Chromel-SR (Stress relieved)
Heat-treated state
Low-temperature stabilizing treatment after coiling or forming to remove cold-work drift and restore calibrated thermoelectric output.
Values for the SR condition
Other Chromel tempers and conditions
Chromel is listed in 6 conditions; see the grade overview at Chromel.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault soft, fully recrystallized thermocouple wire | Standard stocked condition for thermocouple wire, extension/compensating cable conductor and MI-cable cores; best emf stability and bendability. | 275 | 655 | 35 | 80 HRB | — |
Standard limits of error | Ordinary calibration grade for general industrial K-type thermocouples and extension wire. | 275 | 655 | 35 | 150 HB | 2.4 % IACS |
SRThis page Stress relieved | Low-temperature stabilizing treatment after coiling or forming to remove cold-work drift and restore calibrated thermoelectric output. | 330 | 700 | 30 | 160 HB | 2.4 % IACS |
Quarter hard | Choose when slightly stiffer wire is needed for automatic winding or probe assembly while retaining good ductility. | 480 | 760 | 20 | 190 HB | 2.4 % IACS |
Half hard | Stiffer wire and strip for self-supporting sensor elements and formed contacts; anneal after forming to restore emf stability. | 690 | 900 | 10 | 21 HRC | 2.3 % IACS |
Hard Drawn | Maximum strength and springiness for resistance/heating windings and fine wire handling; emf output shifts slightly until stress-relieved. | 900 | 1,100 | 3 | 28 HRC | 2.4 % IACS |
What is Chromel-SR?
Chromel-SR is Chromel heat treated to SR — low-temperature stabilizing treatment after coiling or forming to remove cold-work drift and restore calibrated thermoelectric output. Chromel-SR has a yield strength of 330 MPa (47.9 ksi) and a tensile strength of 700 MPa (102 ksi) — weaker than 67% of nickel alloy grades. Elongation at break is 30% and the elastic modulus is 186 GPa (27 Msi). Chromel-SR has a density of 8.73 g/cm³ (0.315 lb/in³), heavier than 77% of nickel alloy grades. It melts at 1,400°C (2,552 °F). Annealed is the default condition FabDigit quotes; SR is available on request or by drawing note.
Advantages
- Easy to machine — 31/100, better than 95% of nickel alloy grades
- High service temperature — 1,100°C (2,012 °F), better than 88% of nickel alloy grades
- Forms and bends easily — 78/100, better than 87% of nickel alloy grades
- Conducts heat well — 19.2 W/m·K (11.1 BTU/hr·ft·°F), better than 86% of nickel alloy grades
- High electrical conductivity — 2.4 % IACS, better than 84% of nickel alloy grades
Limitations
- Needs corrosion protection — 68/100, worse than 82% of nickel alloy grades
Chromel-SR properties
Typical room-temperature values for Chromel-SR; 21 are specific to this condition. Other listed values are Chromel reference data and may not represent this condition. Bars are the position among nickel alloy grades.
Physical3
Chromel-SR has a density of 8.73 g/cm³ (0.315 lb/in³), heavier than 77% of nickel alloy grades. It melts at 1,400°C (2,552 °F).
Mechanical13
Chromel-SR has a yield strength of 330 MPa (47.9 ksi) and a tensile strength of 700 MPa (102 ksi) — weaker than 67% of nickel alloy grades. Elongation at break is 30% and the elastic modulus is 186 GPa (27 Msi).
Thermal6
Chromel-SR is rated for continuous service to 1,100°C (2,012 °F). It conducts heat at 19.2 W/m·K (11.1 BTU/hr·ft·°F), better than 86% of nickel alloy grades. Thermal expansion is 13.1 µm/m·K (7.28 µin/in·°F).
Electrical3
Chromel-SR conducts electricity at 2.4 % IACS, better than 84% of nickel alloy grades.
Chemical & Environmental3
Corrosion resistance is good (68/100), worse than 82% of nickel alloy grades.
Sustainability4
Producing a kilogram of Chromel-SR takes about 175 MJ of energy and emits 12.5 kg of CO₂ — more than 65% of nickel alloy grades. Typical recycled content is 25%.
Manufacturability8
Chromel-SR's machinability is poor (31/100, better than 95% of nickel alloy grades); weldability very good (75/100); formability very good (78/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Chromel-SR
Is Chromel easy to machine?
Gummy austenitic Ni-Cr solid solution — use sharp positive-rake carbide, rigid setups, low speed with heavy positive feed and flood coolant to avoid work hardening; rarely machined since the alloy is sold as wire.
Can Chromel be welded?
Readily joined by capacitor-discharge, resistance or TIG welding of the thermocouple junction; keep the hot junction free of dissimilar filler and avoid sulphur-bearing fluxes.
Can Chromel be formed, bent or molded?
Excellent cold drawability and bendability in the annealed temper (down to fine gauges); interanneal cold-worked wire and stress-relieve after coiling to recover emf accuracy.
What surface finishes work on Chromel?
Not anodizable; pre-oxidation in clean air forms a protective Cr₂O₃ film, and wire can be electroplated or glass/ceramic-fibre or MgO-insulated for service.
Chromel 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 |
|---|---|---|
| Crgives the positive Seebeck slope and oxidation resistance | 9 – 10.5 | 10 |
| Fe | ≤ 0.5 | 0.2 |
| Sideoxidizer, small emf effect | ≤ 0.4 | 0.2 |
| Mn | ≤ 0.5 | 0.2 |
| C | ≤ 0.15 | 0.05 |
| Skept low to avoid sulphur embrittlement | ≤ 0.02 | — |
| Nibalance, nominally ~90 % | balance | — |
Chromel-SR — frequently asked
What is Chromel-SR used for?
Chromel-SR is typically used for type K thermocouples, temperature sensor wire, mineral-insulated thermocouple cable conductors, furnace and kiln thermocouple probes, type K extension and compensating cable and surface and immersion sensor assemblies. In short: type K positive leg; stable emf to 1100 °C; excellent fine-wire drawability.
What is the yield strength of Chromel-SR?
Chromel-SR has a typical yield strength of 330 MPa (47.9 ksi) and a tensile strength of 700 MPa (102 ksi) — weaker than 67% of nickel alloy grades. Strength varies by condition: see the 6 listed tempers.
Is Chromel-SR easy to machine?
Not especially — machinability is rated poor (31/100, better than 95% of nickel alloy grades). Gummy austenitic Ni-Cr solid solution — use sharp positive-rake carbide, rigid setups, low speed with heavy positive feed and flood coolant to avoid work hardening; rarely machined since the alloy is sold as wire.
Can Chromel-SR be welded?
Yes — weldability is rated very good (75/100). Readily joined by capacitor-discharge, resistance or TIG welding of the thermocouple junction; keep the hot junction free of dissimilar filler and avoid sulphur-bearing fluxes.
What surface finishes work on Chromel-SR?
Not anodizable; pre-oxidation in clean air forms a protective Cr₂O₃ film, and wire can be electroplated or glass/ceramic-fibre or MgO-insulated for service.
Can Chromel-SR be formed, bent or molded?
Excellent cold drawability and bendability in the annealed temper (down to fine gauges); interanneal cold-worked wire and stress-relieve after coiling to recover emf accuracy.
What is the maximum service temperature of Chromel-SR?
Chromel-SR is rated for continuous use to about 1,100°C (2,012 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Chromel Annealed and Chromel-HD?
Annealed is the default condition — standard stocked condition for thermocouple wire, extension/compensating cable conductor and MI-cable cores; best emf stability and bendability. HD: maximum strength and springiness for resistance/heating windings and fine wire handling; emf output shifts slightly until stress-relieved. Yield strength is 275 MPa in Annealed versus 900 MPa in HD.
Sources
- ASTM E230/E230M — Standard Specification and Temperature-EMF Tables for Standardized Thermocouples — ASTM International (2023)
- IEC 60584-1 Thermocouples — EMF specifications and tolerances — IEC (2013)
- ASM Handbook Vol.2 — Properties and Selection: Nonferrous Alloys and Special-Purpose Materials — ASM International (1990)
- Thermocouple alloy physical property tables (Chromel/Alumel type K legs) — Hoskins / Omega Engineering (2022)
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.