Steel K93500-C (Temper C)
Supply condition
UNS K93500
Maximum strength/hardness strip and wire for spring-like or wear-loaded low-expansion parts; ductility, weldability and CTE stability are the trade-offs.
Values for the C condition
Other K93500 tempers and conditions
K93500 is listed in 3 conditions; see the grade overview at K93500.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ADefault Solution annealed | Standard stocked condition: lowest and most stable CTE, best formability and weldability — use for precision structures, LNG membrane, glass sealing and deep-drawn parts. | 280 | 490 | 40 | 140 HB | 2.1 % IACS |
Temper B | Pick when higher yield strength and better chip control are needed and a small CTE shift / later stress-relief is acceptable — springs' blanks, machined precision bodies, stiffer strip. | 520 | 640 | 15 | 18 HRC | 2.1 % IACS |
CThis page Temper C | Maximum strength/hardness strip and wire for spring-like or wear-loaded low-expansion parts; ductility, weldability and CTE stability are the trade-offs. | 740 | 830 | 4 | 27 HRC | 2.1 % IACS |
What is K93500-C?
K93500-C is K93500 supplied in the C condition — maximum strength/hardness strip and wire for spring-like or wear-loaded low-expansion parts; ductility, weldability and CTE stability are the trade-offs. K93500-C has a yield strength of 740 MPa (107 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 83% of steel grades. Elongation at break is 4% and the elastic modulus is 148 GPa (21.5 Msi). K93500-C has a density of 8.05 g/cm³ (0.291 lb/in³), heavier than 96% of steel grades. It melts at 1,427°C (2,601 °F). A is the default condition FabDigit quotes; C is available on request or by drawing note.
Advantages
- Good corrosion resistance — 22/100, better than 90% of steel grades
- High strength — 740 MPa (107 ksi), better than 83% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Limited service temperature — 120°C (248 °F), worse than 100% of steel grades
- Poor heat conductor — 10.5 W/m·K (6.07 BTU/hr·ft·°F), worse than 100% of steel grades
- Low electrical conductivity — 2.1 % IACS, worse than 99% of steel grades
- High embodied carbon — 7.5 kg CO₂/kg, worse than 99% of steel grades
- Low stiffness — 148 GPa (21.5 Msi), worse than 98% of steel grades
K93500-C properties
Typical room-temperature values for K93500-C; 23 are specific to this condition. Other listed values are K93500 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
K93500-C has a density of 8.05 g/cm³ (0.291 lb/in³), heavier than 96% of steel grades. It melts at 1,427°C (2,601 °F).
Mechanical15
K93500-C has a yield strength of 740 MPa (107 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 83% of steel grades. Elongation at break is 4% and the elastic modulus is 148 GPa (21.5 Msi).
Thermal6
K93500-C is rated for continuous service to 120°C (248 °F). It conducts heat at 10.5 W/m·K (6.07 BTU/hr·ft·°F), worse than 100% of steel grades. Thermal expansion is 2 µm/m·K (1.11 µin/in·°F).
Electrical3
K93500-C conducts electricity at 2.1 % IACS, worse than 99% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (22/100), better than 90% of steel grades.
Sustainability4
Producing a kilogram of K93500-C takes about 100 MJ of energy and emits 7.5 kg of CO₂ — more than 99% of steel grades. Typical recycled content is 30%.
Manufacturability8
K93500-C's machinability is fair (42/100, worse than 73% of steel grades); weldability fair (50/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with K93500-C
Is K93500 easy to machine?
Gummy and work-hardening — use sharp positive-rake carbide, rigid setups, heavy positive feed, low-to-moderate speed (25–45 m/min) and flood coolant; avoid dwelling to prevent glazing.
Can K93500 be welded?
GTAW, EBW and laser welding with matching Fe-36Ni filler and low heat input work well; keep sulphur/carbon pickup out of the joint and re-anneal to restore low, uniform CTE.
Can K93500 be formed, bent or molded?
Annealed sheet deep-draws and spins readily but hardens fast — plan interstage anneals at 800–900 °C and a final stress-relief/stabilisation cycle (e.g. 830 °C anneal + 315 °C stabilise) for dimensional parts.
What surface finishes work on K93500?
Not anodizable; protect with electroless nickel, chromium, gold or tin plating, black oxide or oil — bare surfaces rust quickly in humid air and can contaminate optics.
K93500 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 |
|---|---|---|
| NiInvar composition window; exact Ni sets the CTE minimum | 35 – 37 | 36 |
| Clow C for dimensional stability | ≤ 0.1 | 0.03 |
| Mn | ≤ 0.6 | 0.35 |
| Si | ≤ 0.3 | 0.15 |
| P | ≤ 0.03 | — |
| Skept low for glass sealing and weldability | ≤ 0.03 | — |
| Crresidual | ≤ 0.25 | — |
| Coresidual; higher Co gives Super-Invar/Kovar classes | ≤ 0.5 | — |
| Alresidual deoxidiser | ≤ 0.1 | — |
| Fe | balance | — |
K93500-C — frequently asked
What is K93500-C used for?
K93500-C is typically used for glass-to-metal seal components, precision measuring devices, bimetal strip cores and thermostat components. In short: sealing-grade Invar composition; near-zero ambient expansion; poor machinability, needs plating.
What is the yield strength of K93500-C?
K93500-C has a typical yield strength of 740 MPa (107 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 83% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is K93500-C easy to machine?
Not especially — machinability is rated fair (42/100, worse than 73% of steel grades). Gummy and work-hardening — use sharp positive-rake carbide, rigid setups, heavy positive feed, low-to-moderate speed (25–45 m/min) and flood coolant; avoid dwelling to prevent glazing.
Can K93500-C be welded?
With care — weldability is rated fair (50/100). GTAW, EBW and laser welding with matching Fe-36Ni filler and low heat input work well; keep sulphur/carbon pickup out of the joint and re-anneal to restore low, uniform CTE.
What surface finishes work on K93500-C?
Not anodizable; protect with electroless nickel, chromium, gold or tin plating, black oxide or oil — bare surfaces rust quickly in humid air and can contaminate optics.
Can K93500-C be formed, bent or molded?
Annealed sheet deep-draws and spins readily but hardens fast — plan interstage anneals at 800–900 °C and a final stress-relief/stabilisation cycle (e.g. 830 °C anneal + 315 °C stabilise) for dimensional parts.
What is the maximum service temperature of K93500-C?
K93500-C is rated for continuous use to about 120°C (248 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between K93500-A and K93500-C?
A is the default condition — standard stocked condition: lowest and most stable CTE, best formability and weldability — use for precision structures, LNG membrane, glass sealing and deep-drawn parts. C: maximum strength/hardness strip and wire for spring-like or wear-loaded low-expansion parts; ductility, weldability and CTE stability are the trade-offs. Yield strength is 280 MPa in A versus 740 MPa in C.
Sources
- ASTM F1684 – Standard Specification for Iron-Nickel and Iron-Nickel-Cobalt Alloys for Low Thermal Expansion Applications — ASTM International (2022)
- GB/T 15018 / YB/T 5241 4J36 (2018)
- ASM Specialty Handbook: Nickel, Cobalt and Their Alloys / ASM Handbook Vol.2 — ASM International (2000)
- Invar 36 alloy technical datasheet — Carpenter Technology / Aperam-Imphy (2021)
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.