Steel C5 Annealed
Temper
ASTM A217 Grade C5
Intermediate softened state used by foundries/machine shops before the final N&T or Q&T qualifying heat treatment.
Values for the Annealed condition
Other C5 tempers and conditions
C5 is listed in 3 conditions; see the grade overview at C5.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedThis page full anneal (soft condition for rough machining) | Intermediate softened state used by foundries/machine shops before the final N&T or Q&T qualifying heat treatment. | 380 | 590 | 26 | 9 HRC | 3.3 % IACS |
N+TDefault Normalized and tempered | Standard supply condition for A217 C5 valve bodies and pressure castings; balanced strength, creep resistance and machinability. | 470 | 690 | 22 | 16 HRC | — |
Quenched and tempered | Chosen for heavy sections where a fully transformed, uniform tempered structure and higher toughness through thickness are needed. | 510 | 720 | 21 | 18 HRC | — |
What is C5 Annealed?
C5 Annealed is C5 in the Annealed temper — intermediate softened state used by foundries/machine shops before the final N&T or Q&T qualifying heat treatment. C5 Annealed has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 590 MPa (85.6 ksi) — weaker than 68% of steel grades. Elongation at break is 26% and the elastic modulus is 207 GPa (30 Msi). C5 Annealed has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 93% of steel grades. It melts at 1,420°C (2,588 °F). N+T is the default condition FabDigit quotes; Annealed is available on request or by drawing note.
Advantages
- High service temperature — 620°C (1,148 °F), better than 99% of steel grades
- Good corrosion resistance — 28/100, better than 94% of steel grades
- Ductile — tolerates forming and impact — 26%, better than 82% of steel grades
Limitations
- Limited formability — 15/100, worse than 87% of steel grades
C5 Annealed properties
Typical room-temperature values for C5 Annealed; 23 are specific to this condition. Other listed values are C5 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
C5 Annealed has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 93% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
C5 Annealed has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 590 MPa (85.6 ksi) — weaker than 68% of steel grades. Elongation at break is 26% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
C5 Annealed is rated for continuous service to 620°C (1,148 °F). It conducts heat at 37 W/m·K (21.4 BTU/hr·ft·°F), worse than 71% of steel grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical2
C5 Annealed has an electrical resistivity of 5.3×10⁻⁷ Ω·m.
Chemical & Environmental3
Corrosion resistance is poor (28/100), better than 94% of steel grades.
Sustainability4
Producing a kilogram of C5 Annealed takes about 30 MJ of energy and emits 2.3 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 75%.
Manufacturability7
C5 Annealed's machinability is good (55/100, better than 62% of steel grades); weldability fair (40/100); formability poor (15/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C5 Annealed
Is C5 easy to machine?
Machine in the tempered condition with rigid setups, carbide tooling and moderate speeds (~60–90 m/min); the 5% Cr matrix is abrasive and work-hardens if feeds are too light.
Can C5 be welded?
Use matching 5Cr-0.5Mo (E502/ER80S-B6) consumables with 200–300 °C preheat/interpass and mandatory 700–760 °C PWHT; slow cooling is essential to avoid martensitic cracking.
Can C5 be formed, bent or molded?
Supplied only as castings — control pouring temperature and use generous fillets and risers because the alloy air-hardens and is hot-tear sensitive; never cold form.
What surface finishes work on C5?
Normally shot-blasted and painted or aluminized for outdoor use; hot service parts often left bare since Cr provides a protective oxide, and plating is rarely applied.
C5 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 |
|---|---|---|
| C0.20 max per ASTM A217 | ≤ 0.2 | 0.15 |
| Mn | 0.4 – 0.7 | 0.55 |
| Si | ≤ 0.75 | 0.45 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.05 | 0.02 |
| Cr | 4 – 6.5 | 5 |
| Mo | 0.45 – 0.65 | 0.55 |
| Fe | balance | — |
C5 Annealed — frequently asked
What is C5 Annealed used for?
C5 Annealed is typically used for refinery valve bodies, high-temperature hydrocarbon service fittings, hot oil pump casings, catalytic cracking unit piping components, valve bonnets for hydroprocessing units and cast elbows and tees for hot process lines. In short: cast counterpart to P5; 5Cr sulfidation-resistant casting; 620 °C service limit.
What is the yield strength of C5 Annealed?
C5 Annealed has a typical yield strength of 380 MPa (55.1 ksi) and a tensile strength of 590 MPa (85.6 ksi) — weaker than 68% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is C5 Annealed easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machine in the tempered condition with rigid setups, carbide tooling and moderate speeds (~60–90 m/min); the 5% Cr matrix is abrasive and work-hardens if feeds are too light.
Can C5 Annealed be welded?
With care — weldability is rated fair (40/100). Use matching 5Cr-0.5Mo (E502/ER80S-B6) consumables with 200–300 °C preheat/interpass and mandatory 700–760 °C PWHT; slow cooling is essential to avoid martensitic cracking.
What surface finishes work on C5 Annealed?
Normally shot-blasted and painted or aluminized for outdoor use; hot service parts often left bare since Cr provides a protective oxide, and plating is rarely applied.
Can C5 Annealed be formed, bent or molded?
Supplied only as castings — control pouring temperature and use generous fillets and risers because the alloy air-hardens and is hot-tear sensitive; never cold form.
What is the maximum service temperature of C5 Annealed?
C5 Annealed is rated for continuous use to about 620°C (1,148 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ASTM A217/A217M — Steel Castings, Martensitic Stainless and Alloy, for Pressure-Containing Parts, Suitable for High-Temperature Service — ASTM International (2021)
- ASME BPVC Section II Part D — Material Properties (5Cr-1/2Mo) — ASME (2023)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- GB/T 16253 (ZG16Cr5Mo) — SAC (2019)
- API 941 — Steels for Hydrogen Service at Elevated Temperatures — API (2016)
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.