Steel Ductile Iron · temper
Steel Ductile Iron Annealed
Properties of the Annealed condition, compared with the other Ductile Iron tempers.
Pick when maximum ductility, impact energy and low-temperature toughness matter — pressure pipe, fittings, wind-turbine and safety-critical castings.
What is Ductile Iron Annealed?
Ductile Iron Annealed is Ductile Iron in the Annealed temper — pick when maximum ductility, impact energy and low-temperature toughness matter — pressure pipe, fittings, wind-turbine and safety-critical castings. Ductile Iron Annealed has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 440 MPa (63.8 ksi) — weaker than 86% of steel grades. Elongation at break is 20% and the elastic modulus is 169 GPa (24.5 Msi). Ductile Iron Annealed has a density of 7.1 g/cm³ (0.257 lb/in³), lighter than 100% of steel grades. It melts at 1,150°C (2,102 °F). As Cast is the default condition FabDigit quotes; Annealed is available on request or by drawing note.
Advantages
- Easy to machine — 75/100, better than 97% of steel grades
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
- High service temperature — 450°C (842 °F), better than 86% of steel grades
Limitations
- Low stiffness — 169 GPa (24.5 Msi), worse than 97% of steel grades
- Limited formability — 8/100, worse than 97% of steel grades
- Low electrical conductivity — 3.1 % IACS, worse than 89% of steel grades
- Low strength — 300 MPa (43.5 ksi), worse than 86% of steel grades
- Low fracture toughness — 55 MPa·√m (50.1 ksi·√in), worse than 83% of steel grades
Ductile Iron Annealed properties
Typical room-temperature values for Ductile Iron Annealed — 16 properties are specific to this condition; the rest are grade-level values shared by every Ductile Iron temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
Ductile Iron Annealed has a density of 7.1 g/cm³ (0.257 lb/in³), lighter than 100% of steel grades. It melts at 1,150°C (2,102 °F).
Mechanical15
Ductile Iron Annealed has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 440 MPa (63.8 ksi) — weaker than 86% of steel grades. Elongation at break is 20% and the elastic modulus is 169 GPa (24.5 Msi).
Thermal6
Ductile Iron Annealed is rated for continuous service to 450°C (842 °F). It conducts heat at 36 W/m·K (20.8 BTU/hr·ft·°F), worse than 72% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
Ductile Iron Annealed conducts electricity at 3.1 % IACS, worse than 89% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (16/100), better than 79% of steel grades.
Sustainability4
Producing a kilogram of Ductile Iron Annealed takes about 21 MJ of energy and emits 1.9 kg of CO₂ — less than 99% of steel grades. Typical recycled content is 85%.
Manufacturability8
Ductile Iron Annealed's machinability is very good (75/100, better than 97% of steel grades); weldability fair (45/100); formability not recommended (8/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other Ductile Iron tempers and conditions
Ductile Iron is also supplied in 5 other conditions. The full side-by-side table is on the Ductile Iron overview.
- As CastDefaultDefault stocked condition: best cost/strength balance for general machinery castings, housings and brackets.340 MPa yield · 187 HB
- ADIPick when you want steel-level strength and fatigue life plus useful ductility and wear resistance at casting cost — suspension arms, track links, gears, ground-engaging tools.750 MPa yield · 35 HRC
- Q&TPick for maximum strength and wear life in ductile iron where low elongation is acceptable — dies, rolls, high-load gears and pins.700 MPa yield · 34 HRC
- N&TPick for higher strength and wear resistance with moderate ductility — gears, crankshafts, sprockets, heavy-duty linkages.510 MPa yield · 25 HRC
- AnnealedPick when maximum ductility, impact energy and low-temperature toughness matter — pressure pipe, fittings, wind-turbine and safety-critical castings.300 MPa yield · 160 HB
Working with Ductile Iron Annealed
Is Ductile Iron easy to machine?
Machines better than steel of equal hardness — carbide at 150–300 m/min for ferritic/pearlitic grades, dry or with light coolant; watch for hard carbides in thin chilled sections and use CBN on Q&T/ADI.
Can Ductile Iron be welded?
Poor as-welded: use Ni or Ni-Fe electrodes (ENiFe-CI), 200–350 °C preheat, short low-heat beads with peening, then ferritize/stress-relieve to avoid carbides and martensite in the HAZ.
Can Ductile Iron be formed, bent or molded?
A casting alloy — green sand, shell, no-bake or permanent mold with Mg treatment plus late inoculation; feed for shrinkage and keep section modulus consistent since nodule count and matrix are section-sensitive, and it is not cold formed.
What surface finishes work on Ductile Iron?
No anodizing; shot blast then paint, powder coat, zinc/phosphate or electroless nickel; cement-mortar or fusion-bonded epoxy lining for water pipe; can be flame/induction hardened or nitrided for wear surfaces.
Ductile Iron 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 |
|---|---|---|
| Ctotal carbon; CE typically 4.3–4.6 | 3.2 – 3.9 | 3.6 |
| Sihigher Si strengthens ferrite, lowers toughness | 1.8 – 2.9 | 2.4 |
| Mnkept low for ferritic grades | 0.1 – 0.6 | 0.3 |
| Mgresidual Mg for nodularization | 0.03 – 0.06 | 0.04 |
| P | ≤ 0.05 | 0.03 |
| S | ≤ 0.02 | 0.01 |
| Cuoptional pearlite stabilizer (higher-strength grades) | 0 – 0.8 | 0.2 |
| Nioptional, hardenability/toughness | 0 – 1 | — |
| Mooptional, for ADI/Q&T sections | 0 – 0.4 | — |
| Fe | balance | — |
Ductile Iron Annealed — frequently asked
What is Ductile Iron Annealed used for?
Ductile Iron Annealed is typically used for water and sewer pressure pipe and fittings, valve and pump housings, engine blocks and crankshafts, gearbox housings and gears, wheel hubs and steering knuckles and machine tool bases and heavy brackets. In short: stronger than gray iron.
What is the yield strength of Ductile Iron Annealed?
Ductile Iron Annealed has a typical yield strength of 300 MPa (43.5 ksi) and a tensile strength of 440 MPa (63.8 ksi) — weaker than 86% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is Ductile Iron Annealed easy to machine?
Yes — machinability is rated very good (75/100, better than 97% of steel grades). Machines better than steel of equal hardness — carbide at 150–300 m/min for ferritic/pearlitic grades, dry or with light coolant; watch for hard carbides in thin chilled sections and use CBN on Q&T/ADI.
Can Ductile Iron Annealed be welded?
With care — weldability is rated fair (45/100). Poor as-welded: use Ni or Ni-Fe electrodes (ENiFe-CI), 200–350 °C preheat, short low-heat beads with peening, then ferritize/stress-relieve to avoid carbides and martensite in the HAZ.
What surface finishes work on Ductile Iron Annealed?
No anodizing; shot blast then paint, powder coat, zinc/phosphate or electroless nickel; cement-mortar or fusion-bonded epoxy lining for water pipe; can be flame/induction hardened or nitrided for wear surfaces.
Can Ductile Iron Annealed be formed, bent or molded?
A casting alloy — green sand, shell, no-bake or permanent mold with Mg treatment plus late inoculation; feed for shrinkage and keep section modulus consistent since nodule count and matrix are section-sensitive, and it is not cold formed.
What is the maximum service temperature of Ductile Iron Annealed?
Ductile Iron Annealed is rated for continuous use to about 450°C (842 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Ductile Iron As Cast and Ductile Iron-ADI?
As Cast is the default condition — default stocked condition: best cost/strength balance for general machinery castings, housings and brackets. ADI: pick when you want steel-level strength and fatigue life plus useful ductility and wear resistance at casting cost — suspension arms, track links, gears, ground-engaging tools. Yield strength is 340 MPa in As Cast versus 750 MPa in ADI.
Can FabDigit make parts in Ductile Iron Annealed?
Yes — Ductile Iron Annealed is available for CNC machining and casting & forging with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM A536 — Standard Specification for Ductile Iron Castings — ASTM International (2019)
- ASTM A897/A897M — Austempered Ductile Iron Castings — ASTM International (2022)
- EN 1563 — Founding: Spheroidal graphite cast irons — CEN (2018)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- Ductile Iron Data for Design Engineers — Ductile Iron Society / Rio Tinto Iron & Titanium (2013)
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.