Steel ZG55SiMnMo N+T
Heat-treated state
N+T = normalized and tempered
Balanced strength/toughness for large or thick-walled castings where oil/water quenching would crack them.
Values for the N+T condition
Other ZG55SiMnMo tempers and conditions
ZG55SiMnMo is listed in 7 conditions; see the grade overview at ZG55SiMnMo.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Pick for stress relief and softest structure before rough machining or welding repair of the casting. | 400 | 700 | 14 | 210 HB | — |
As fabricated | Cheapest condition, only for low-stress or rough non-critical castings; coarse as-cast structure with residual casting stresses. | 430 | 750 | 6 | 26 HRC | 6.5 % IACS |
N+TThis page Normalized and tempered | Balanced strength/toughness for large or thick-walled castings where oil/water quenching would crack them. | 650 | 950 | 10 | 31 HRC | — |
quenched and tempered ~350–420 °C | Choose when impact loading dominates over pure abrasion (crusher jaws, hammer bodies, shovel teeth). | 1,150 | 1,400 | 7 | 42 HRC | — |
Austempered / isothermally quenched to lower bainite | Use for heavy-impact wear parts needing 45–50 HRC with clearly higher toughness and lower distortion/cracking risk than martensitic Q&T. | 1,200 | 1,500 | 8 | 47 HRC | — |
QT45-50HRCDefault quenched (oil/water-mist) and tempered ~250–320 °C | Standard supply condition for ball-mill liners and crusher wear parts — best compromise of abrasion resistance and impact toughness. | 1,300 | 1,600 | 5 | 47 HRC | — |
quenched and low-temperature tempered ~180–230 °C | Maximum abrasion resistance for fine-grinding liners, chute plates and sand-slurry parts where impact energy is low. | 1,450 | 1,800 | 3 | 53 HRC | — |
What is ZG55SiMnMo N+T?
ZG55SiMnMo N+T is ZG55SiMnMo heat treated to N+T — balanced strength/toughness for large or thick-walled castings where oil/water quenching would crack them. ZG55SiMnMo N+T has a yield strength of 650 MPa (94.3 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 79% of steel grades. Elongation at break is 10% and the elastic modulus is 205 GPa (29.7 Msi). ZG55SiMnMo N+T has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,420°C (2,588 °F). QT45-50HRC is the default condition FabDigit quotes; N+T is available on request or by drawing note.
Advantages
- High strength — 650 MPa (94.3 ksi), better than 79% of steel grades
Limitations
- Limited formability — 5/100, worse than 99% of steel grades
- Limited ductility — 10%, worse than 91% of steel grades
- Low fracture toughness — 45 MPa·√m (41 ksi·√in), worse than 90% of steel grades
- Difficult to machine — 32/100, worse than 87% of steel grades
- Low electrical conductivity — 6.2 % IACS, worse than 78% of steel grades
ZG55SiMnMo N+T properties
Typical room-temperature values for ZG55SiMnMo N+T; 11 are specific to this condition. Other listed values are ZG55SiMnMo reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
ZG55SiMnMo N+T has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
ZG55SiMnMo N+T has a yield strength of 650 MPa (94.3 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 79% of steel grades. Elongation at break is 10% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
ZG55SiMnMo N+T is rated for continuous service to 400°C (752 °F). It conducts heat at 38 W/m·K (22 BTU/hr·ft·°F), worse than 69% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
ZG55SiMnMo N+T conducts electricity at 6.2 % IACS, worse than 78% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of ZG55SiMnMo N+T takes about 26 MJ of energy and emits 2 kg of CO₂ — less than 64% of steel grades. Typical recycled content is 80%.
Manufacturability8
ZG55SiMnMo N+T's machinability is poor (32/100, worse than 87% of steel grades); weldability poor (25/100); formability not recommended (5/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with ZG55SiMnMo N+T
Is ZG55SiMnMo easy to machine?
Rough-machine in the annealed or as-cast state; above ~45 HRC use CBN/ceramic inserts or grinding, rigid setups and low feeds.
Can ZG55SiMnMo be welded?
Crack-sensitive (high CE): preheat 250–350 °C, low-hydrogen or austenitic-buffer electrodes, and temper immediately after welding; keep welds out of high-stress wear zones.
Can ZG55SiMnMo be formed, bent or molded?
Sand-cast only — provide generous fillets and directional feeding, control Si-related shrinkage porosity, and always normalize or quench-and-temper before service.
What surface finishes work on ZG55SiMnMo?
Shot-blast and paint or oil for storage; no anodizing. Hard-facing overlays or phosphate coatings are common for extra service life.
ZG55SiMnMo 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-defining carbon level | 0.5 – 0.6 | 0.55 |
| Sisome works standards run Si up to 1.6–2.0 % for extra solid-solution strength | 0.8 – 1.2 | 1 |
| Mn | 1.1 – 1.6 | 1.35 |
| Mohardenability + temper-embrittlement resistance | 0.2 – 0.35 | 0.28 |
| Crresidual, sometimes added intentionally | ≤ 0.3 | — |
| Niresidual | ≤ 0.3 | — |
| Pimpurity limit | ≤ 0.04 | — |
| Simpurity limit | ≤ 0.04 | — |
| Fe | balance | — |
ZG55SiMnMo N+T — frequently asked
What is ZG55SiMnMo N+T used for?
ZG55SiMnMo N+T is typically used for crusher hammers, ball mill liners and excavator teeth. In short: hardest cast wear grade; 460 HB in service; abrasion-first cast steel.
What is the yield strength of ZG55SiMnMo N+T?
ZG55SiMnMo N+T has a typical yield strength of 650 MPa (94.3 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 79% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is ZG55SiMnMo N+T easy to machine?
Not especially — machinability is rated poor (32/100, worse than 87% of steel grades). Rough-machine in the annealed or as-cast state; above ~45 HRC use CBN/ceramic inserts or grinding, rigid setups and low feeds.
Can ZG55SiMnMo N+T be welded?
Not readily — weldability is rated poor (25/100). Crack-sensitive (high CE): preheat 250–350 °C, low-hydrogen or austenitic-buffer electrodes, and temper immediately after welding; keep welds out of high-stress wear zones.
What surface finishes work on ZG55SiMnMo N+T?
Shot-blast and paint or oil for storage; no anodizing. Hard-facing overlays or phosphate coatings are common for extra service life.
Can ZG55SiMnMo N+T be formed, bent or molded?
Sand-cast only — provide generous fillets and directional feeding, control Si-related shrinkage porosity, and always normalize or quench-and-temper before service.
What is the maximum service temperature of ZG55SiMnMo N+T?
ZG55SiMnMo 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 ZG55SiMnMo QT45-50HRC and ZG55SiMnMo-A?
QT45-50HRC is the default condition — standard supply condition for ball-mill liners and crusher wear parts — best compromise of abrasion resistance and impact toughness. A: pick for stress relief and softest structure before rough machining or welding repair of the casting. Yield strength is 1,300 MPa in QT45-50HRC versus 400 MPa in A.
Sources
- GB/T 26651 (Wear-resistant steel castings) (2011)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (steel castings, Q&T low-alloy steel) — ASM International (1990)
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.