Steel Ductile Iron · heat-treated state
Steel Ductile Iron N&T
Properties of the N&T condition, compared with the other Ductile Iron tempers.
Pick for higher strength and wear resistance with moderate ductility — gears, crankshafts, sprockets, heavy-duty linkages.
What is Ductile Iron N&T?
Ductile Iron N&T is Ductile Iron heat treated to N&T — pick for higher strength and wear resistance with moderate ductility — gears, crankshafts, sprockets, heavy-duty linkages. Ductile Iron N&T has a yield strength of 510 MPa (74 ksi) and a tensile strength of 730 MPa (106 ksi) — stronger than 65% of steel grades. Elongation at break is 5% and the elastic modulus is 169 GPa (24.5 Msi). Ductile Iron N&T 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; N&T is available on request or by drawing note.
Advantages
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
Limitations
- Limited ductility — 5%, worse than 98% of steel grades
- Low stiffness — 169 GPa (24.5 Msi), worse than 97% of steel grades
- Limited formability — 8/100, worse than 97% of steel grades
- Low fracture toughness — 38 MPa·√m (34.6 ksi·√in), worse than 94% of steel grades
- Low electrical conductivity — 3.1 % IACS, worse than 89% of steel grades
Ductile Iron N&T properties
Typical room-temperature values for Ductile Iron N&T — 15 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 N&T 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 N&T has a yield strength of 510 MPa (74 ksi) and a tensile strength of 730 MPa (106 ksi) — stronger than 65% of steel grades. Elongation at break is 5% and the elastic modulus is 169 GPa (24.5 Msi).
Thermal6
Ductile Iron N&T is rated for continuous service to 400°C (752 °F). It conducts heat at 30 W/m·K (17.3 BTU/hr·ft·°F), worse than 83% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
Ductile Iron N&T 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 N&T 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 N&T's machinability is good (55/100, better than 62% of steel grades); weldability poor (25/100); 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 N&T
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 N&T — frequently asked
What is Ductile Iron N&T used for?
Ductile Iron N&T 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 N&T?
Ductile Iron N&T has a typical yield strength of 510 MPa (74 ksi) and a tensile strength of 730 MPa (106 ksi) — stronger than 65% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is Ductile Iron N&T easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% 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 N&T be welded?
Not readily — weldability is rated poor (25/100). 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 N&T?
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 N&T 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 N&T?
Ductile Iron N&T is rated for continuous use to about 400°C (752 °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 N&T?
Yes — Ductile Iron N&T 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.