Stainless Steel CD4MCu-AC (Spheroidize annealed)
Heat-treated state
ASTM CD4MCu · UNS J93370 · EN 1.4517, GX2CrNiMoCuN25-6-3-3
Foundry raw state only — brittle intermetallics and unbalanced phase ratio; must be solution treated before service.
Values for the AC condition
Other CD4MCu tempers and conditions
CD4MCu is listed in 6 conditions; see the grade overview at CD4MCu.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ACThis page Spheroidize annealed | Foundry raw state only — brittle intermetallics and unbalanced phase ratio; must be solution treated before service. | 520 | 640 | 8 | 25 HRC | 2.2 % IACS |
SADefault Solution annealed ~1120 °C, water quenched | Standard supply condition for all pressure-retaining and corrosion service castings. | 550 | 745 | 25 | 21 HRC | — |
SA, nitrogen-alloyed CD4MCuN | Choose when higher ductility/toughness and better phase-balance control are required; N addition stabilises austenite. | 555 | 760 | 30 | 22 HRC | 2.2 % IACS |
HIP + solution annealed and water quenched | Specify for thick, fatigue- or leak-critical castings where internal microporosity must be closed. | 560 | 770 | 30 | 21 HRC | 2.2 % IACS |
Centrifugally cast tube/ring, solution annealed | Use for cylindrical pump liners, sleeves and rings where a denser, more uniform wall structure is wanted. | 565 | 770 | 28 | 22 HRC | 2.2 % IACS |
SA, high-strength nitrogen grade | Higher-strength N-bearing version of the 25Cr-5Ni-2Mo-3Cu family for highly loaded pump and valve parts. | 580 | 790 | 26 | 23 HRC | 2.1 % IACS |
What is CD4MCu-AC?
CD4MCu-AC is CD4MCu heat treated to AC — foundry raw state only — brittle intermetallics and unbalanced phase ratio; must be solution treated before service. CD4MCu-AC has a yield strength of 520 MPa (75.4 ksi) and a tensile strength of 640 MPa (92.8 ksi) — stronger than 79% of stainless steel grades. Elongation at break is 8% and the elastic modulus is 200 GPa (29 Msi). CD4MCu-AC has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 65% of stainless steel grades. It melts at 1,400°C (2,552 °F). SA is the default condition FabDigit quotes; AC is available on request or by drawing note.
Advantages
- High strength — 520 MPa (75.4 ksi), better than 79% of stainless steel grades
Limitations
- Limited ductility — 8%, worse than 99% of stainless steel grades
- Limited service temperature — 250°C (482 °F), worse than 99% of stainless steel grades
- Low fracture toughness — 45 MPa·√m (41 ksi·√in), worse than 95% of stainless steel grades
- Limited formability — 10/100, worse than 95% of stainless steel grades
- Difficult to machine — 24/100, worse than 93% of stainless steel grades
CD4MCu-AC properties
Typical room-temperature values for CD4MCu-AC; 23 are specific to this condition. Other listed values are CD4MCu reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
CD4MCu-AC has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 65% of stainless steel grades. It melts at 1,400°C (2,552 °F).
Mechanical16
CD4MCu-AC has a yield strength of 520 MPa (75.4 ksi) and a tensile strength of 640 MPa (92.8 ksi) — stronger than 79% of stainless steel grades. Elongation at break is 8% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
CD4MCu-AC is rated for continuous service to 250°C (482 °F). It conducts heat at 16 W/m·K (9.24 BTU/hr·ft·°F), better than 58% of stainless steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
CD4MCu-AC conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (55/100), worse than 71% of stainless steel grades.
Sustainability4
Producing a kilogram of CD4MCu-AC takes about 53 MJ of energy and emits 4.6 kg of CO₂ — less than 67% of stainless steel grades. Typical recycled content is 75%.
Manufacturability8
CD4MCu-AC's machinability is poor (24/100, worse than 93% of stainless steel grades); weldability fair (45/100); formability not recommended (10/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with CD4MCu-AC
Is CD4MCu easy to machine?
Work-hardening and abrasive — use rigid setups, positive-rake carbide, ~60–90 m/min surface speed, heavy constant feed and copious coolant; avoid dwelling.
Can CD4MCu be welded?
Weld with over-alloyed duplex filler (E/ER2553 or 25.10.4L) at controlled 0.5–2.5 kJ/mm heat input and interpass <150 °C; major repairs should be re-solution annealed and water quenched.
Can CD4MCu be formed, bent or molded?
Supplied as sand, investment or centrifugal castings; solution treat 1050–1120 °C followed by rapid water quench to dissolve sigma and balance ferrite/austenite.
What surface finishes work on CD4MCu?
Grit blast, pickle and passivate (nitric or citric acid) after heat treatment; electropolishing improves pitting resistance — no anodizing, and avoid iron contamination from carbon-steel tooling.
CD4MCu 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 |
|---|---|---|
| CGrade 1A max | ≤ 0.04 | 0.03 |
| Mn | ≤ 1 | 0.7 |
| Si | ≤ 1 | 0.8 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.04 | 0.02 |
| Cr | 24.5 – 26.5 | 25.5 |
| Ni | 4.75 – 6 | 5.4 |
| Mo | 1.75 – 2.25 | 2 |
| Cu | 2.75 – 3.25 | 3 |
| Nnot specified for Gr 1A; 0.10–0.25 % for the CD4MCuN variants (Gr 1B/1C) | — | — |
| Fe | balance | — |
CD4MCu-AC — frequently asked
What is CD4MCu-AC used for?
CD4MCu-AC is typically used for slurry pumps, valve trim and bodies, phosphoric and sulfuric acid handling equipment and marine pump casings. In short: cu-bearing cast duplex; strong erosion-corrosion resistance; higher strength than cast austenitics.
What is the yield strength of CD4MCu-AC?
CD4MCu-AC has a typical yield strength of 520 MPa (75.4 ksi) and a tensile strength of 640 MPa (92.8 ksi) — stronger than 79% of stainless steel grades. Strength varies by condition: see the 6 listed tempers.
Is CD4MCu-AC easy to machine?
Not especially — machinability is rated poor (24/100, worse than 93% of stainless steel grades). Work-hardening and abrasive — use rigid setups, positive-rake carbide, ~60–90 m/min surface speed, heavy constant feed and copious coolant; avoid dwelling.
Can CD4MCu-AC be welded?
With care — weldability is rated fair (45/100). Weld with over-alloyed duplex filler (E/ER2553 or 25.10.4L) at controlled 0.5–2.5 kJ/mm heat input and interpass <150 °C; major repairs should be re-solution annealed and water quenched.
What surface finishes work on CD4MCu-AC?
Grit blast, pickle and passivate (nitric or citric acid) after heat treatment; electropolishing improves pitting resistance — no anodizing, and avoid iron contamination from carbon-steel tooling.
Can CD4MCu-AC be formed, bent or molded?
Supplied as sand, investment or centrifugal castings; solution treat 1050–1120 °C followed by rapid water quench to dissolve sigma and balance ferrite/austenite.
What is the maximum service temperature of CD4MCu-AC?
CD4MCu-AC is rated for continuous use to about 250°C (482 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between CD4MCu-SA and CD4MCu-AC?
SA is the default condition — standard supply condition for all pressure-retaining and corrosion service castings. AC: foundry raw state only — brittle intermetallics and unbalanced phase ratio; must be solution treated before service. Yield strength is 550 MPa in SA versus 520 MPa in AC.
Sources
- ASTM A890/A890M — Castings, Iron-Chromium-Nickel-Molybdenum Corrosion-Resistant, Duplex — ASTM International (2023)
- ASTM A995/A995M — Castings, Austenitic-Ferritic (Duplex) Stainless Steel for Pressure-Containing Parts — ASTM International (2020)
- EN 10283 — Corrosion resistant steel castings (1.4517 GX2CrNiMoCuN25-6-3-3) — CEN (2019)
- Steel Castings Handbook, Supplement 8 — High Alloy Data Sheets, Corrosion Series — Steel Founders' Society of America (2004)
- ASM Handbook Vol. 1: Properties and Selection — Irons, Steels, and High-Performance Alloys — ASM International (1990)
- GB/T 2100 / GB/T 23879 (2017)
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.