Stainless Steel Alloy 864 CW-FH
Supply condition
UNS S35135
CW-FH = cold Worked, Full Hard / Spring temper
Maximum strength condition for wire, springs and braid used in exhaust flex couplings; very limited ductility.
Values for the CW-FH condition
Other Alloy 864 tempers and conditions
Alloy 864 is listed in 7 conditions; see the grade overview at Alloy 864.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Hot Rolled, Annealed and Pickled | Heavier sections for furnace fixtures, retorts and radiant tubes; slightly lower strength and coarser grain than cold-rolled annealed strip. | 270 | 600 | 45 | 165 HB | 1.7 % IACS |
AnnealedDefault Annealed (solution annealed, sheet/strip/tube) | Standard stocked condition: maximum ductility for bellows/flex-tube forming and best corrosion/oxidation performance. | 290 | 620 | 45 | 170 HB | — |
Cold drawn | Choose for close-tolerance bar and tube where higher yield strength and better surface finish are needed than annealed. | 520 | 760 | 25 | 20 HRC | 1.7 % IACS |
Stress relieved | Use when cold-formed bellows or springs need residual stress reduction and dimensional stability before hot service. | 600 | 830 | 20 | 23 HRC | 1.7 % IACS |
Cold Worked, 1/4 Hard | Light temper for spring-back-controlled clamps, gaskets and formed parts needing extra stiffness. | 620 | 830 | 18 | 25 HRC | 1.7 % IACS |
Cold Worked, 1/2 Hard | Higher-strength strip/wire for clamps, mesh and springs used below the recrystallization range. | 760 | 965 | 10 | 31 HRC | 1.7 % IACS |
CW-FHThis page Cold Worked, Full Hard / Spring temper | Maximum strength condition for wire, springs and braid used in exhaust flex couplings; very limited ductility. | 965 | 1,150 | 5 | 36 HRC | 1.7 % IACS |
What is Alloy 864 CW-FH?
Alloy 864 CW-FH is Alloy 864 supplied in the CW-FH condition — maximum strength condition for wire, springs and braid used in exhaust flex couplings; very limited ductility. Alloy 864 CW-FH has a yield strength of 965 MPa (140 ksi) and a tensile strength of 1,150 MPa (167 ksi) — stronger than 98% of stainless steel grades. Elongation at break is 5% and the elastic modulus is 197 GPa (28.6 Msi). Alloy 864 CW-FH has a density of 7.94 g/cm³ (0.287 lb/in³), heavier than 78% of stainless steel grades. It melts at 1,355°C (2,471 °F). Annealed is the default condition FabDigit quotes; CW-FH is available on request or by drawing note.
Advantages
- High strength — 965 MPa (140 ksi), better than 98% of stainless steel grades
Limitations
- Limited ductility — 5%, worse than 100% of stainless steel grades
- Poor heat conductor — 11.5 W/m·K (6.64 BTU/hr·ft·°F), worse than 97% of stainless steel grades
- High embodied carbon — 7 kg CO₂/kg, worse than 96% of stainless steel grades
- Low electrical conductivity — 1.7 % IACS, worse than 93% of stainless steel grades
- Difficult to machine — 24/100, worse than 93% of stainless steel grades
Alloy 864 CW-FH properties
Typical room-temperature values for Alloy 864 CW-FH; 23 are specific to this condition. Other listed values are Alloy 864 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
Alloy 864 CW-FH has a density of 7.94 g/cm³ (0.287 lb/in³), heavier than 78% of stainless steel grades. It melts at 1,355°C (2,471 °F).
Mechanical14
Alloy 864 CW-FH has a yield strength of 965 MPa (140 ksi) and a tensile strength of 1,150 MPa (167 ksi) — stronger than 98% of stainless steel grades. Elongation at break is 5% and the elastic modulus is 197 GPa (28.6 Msi).
Thermal5
Alloy 864 CW-FH is rated for continuous service to 370°C (698 °F). It conducts heat at 11.5 W/m·K (6.64 BTU/hr·ft·°F), worse than 97% of stainless steel grades. Thermal expansion is 14.4 µm/m·K (8 µin/in·°F).
Electrical3
Alloy 864 CW-FH conducts electricity at 1.7 % IACS, worse than 93% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (54/100), worse than 75% of stainless steel grades.
Sustainability4
Producing a kilogram of Alloy 864 CW-FH takes about 95 MJ of energy and emits 7 kg of CO₂ — more than 96% of stainless steel grades. Typical recycled content is 35%.
Manufacturability6
Alloy 864 CW-FH's machinability is poor (24/100, worse than 93% of stainless steel grades); weldability good (60/100); formability poor (15/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Alloy 864 CW-FH
Is Alloy 864 easy to machine?
Machine like a Ni-Fe-Cr heat-resisting alloy: rigid setup, sharp positive-rake carbide, low speed / heavy positive feed to cut under the work-hardened layer, flood coolant, avoid dwelling.
Can Alloy 864 be welded?
Readily joined by GTAW/GMAW/PAW with matching or Ni-base filler (e.g. ERNiCrMo-3 / 82-type); keep interpass temperature low, no preheat required, no post-weld heat treatment normally needed.
Can Alloy 864 be formed, bent or molded?
Excellent cold formability for bellows, convolutions and deep-drawn parts; work-hardening rate is high, so plan intermediate solution anneals (~1065–1120 °C, rapid cool) for severe forming.
What surface finishes work on Alloy 864?
Pickle/passivate after hot work to restore the chromia film; takes a good mechanical and electropolished finish; no anodizing — plating or paint is rarely needed for exhaust/furnace service.
Alloy 864 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 |
|---|---|---|
| Niprimary austenite stabilizer, gives chloride-SCC and carburization resistance | 33 – 35 | 34 |
| Croxidation/scale resistance | 20 – 22 | 21 |
| Mopitting resistance and high-temperature strength | 3.5 – 4.5 | 4.2 |
| Ticarbide stabilization | 0.15 – 0.6 | 0.4 |
| Si | ≤ 1 | 0.5 |
| Mn | ≤ 1 | 0.5 |
| C | ≤ 0.05 | 0.03 |
| S | ≤ 0.02 | — |
| P | ≤ 0.03 | — |
| Febalance, approx. 37–40 % | balance | — |
Alloy 864 CW-FH — frequently asked
What is Alloy 864 CW-FH used for?
Alloy 864 CW-FH is typically used for pyrolysis furnace tubing, high-temperature fixtures, radiant coils and carburizing furnace hardware. In short: best-forming heat-resistant superaustenitic; carburization-resistant furnace alloy; upgrade over 321/347.
What is the yield strength of Alloy 864 CW-FH?
Alloy 864 CW-FH has a typical yield strength of 965 MPa (140 ksi) and a tensile strength of 1,150 MPa (167 ksi) — stronger than 98% of stainless steel grades. Strength varies by condition: see the 7 listed tempers.
Is Alloy 864 CW-FH easy to machine?
Not especially — machinability is rated poor (24/100, worse than 93% of stainless steel grades). Machine like a Ni-Fe-Cr heat-resisting alloy: rigid setup, sharp positive-rake carbide, low speed / heavy positive feed to cut under the work-hardened layer, flood coolant, avoid dwelling.
Can Alloy 864 CW-FH be welded?
Yes — weldability is rated good (60/100). Readily joined by GTAW/GMAW/PAW with matching or Ni-base filler (e.g. ERNiCrMo-3 / 82-type); keep interpass temperature low, no preheat required, no post-weld heat treatment normally needed.
What surface finishes work on Alloy 864 CW-FH?
Pickle/passivate after hot work to restore the chromia film; takes a good mechanical and electropolished finish; no anodizing — plating or paint is rarely needed for exhaust/furnace service.
Can Alloy 864 CW-FH be formed, bent or molded?
Excellent cold formability for bellows, convolutions and deep-drawn parts; work-hardening rate is high, so plan intermediate solution anneals (~1065–1120 °C, rapid cool) for severe forming.
What is the maximum service temperature of Alloy 864 CW-FH?
Alloy 864 CW-FH is rated for continuous use to about 370°C (698 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Alloy 864 Annealed and Alloy 864 CW-FH?
Annealed is the default condition — standard stocked condition: maximum ductility for bellows/flex-tube forming and best corrosion/oxidation performance. CW-FH: maximum strength condition for wire, springs and braid used in exhaust flex couplings; very limited ductility. Yield strength is 290 MPa in Annealed versus 965 MPa in CW-FH.
Sources
- INCOLOY alloy 864 (UNS S35135) technical bulletin — Special Metals Corporation (2004)
- ASTM B815 / ASTM A1058-family test practice and UNS S35135 registration — ASTM International / SAE-ASTM UNS (2020)
- ASM Handbook Vol. 1: Properties and Selection — Heat-Resistant Fe-Ni-Cr Alloys — ASM International (1990)
- ASM Specialty Handbook: Heat-Resistant Materials — ASM International (1997)
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.