Steel ZG42CrMo
ZG42CrMo is a higher-carbon chromium-molybdenum cast steel, the cast equivalent of wrought 42CrMo, used where cast parts need higher strength and hardenability than ZG35CrMo.
Reference datasheet — ZG42CrMo is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the QT-240-280HB condition
ZG42CrMo tempers and conditions
ZG42CrMo is supplied in 10 conditions, soft to hard. QT-240-280HB is the default FabDigit quotes; the values on this page are for it.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Softest condition for heavy rough machining or to relieve casting stresses before final quench and temper. | 380 | 650 | 18 | 11 HRC | 7.9 % IACS |
As fabricated | Raw casting before heat treatment; used only for rough-machining stock or parts to be treated later. | 420 | 720 | 7 | 20 HRC | 7.8 % IACS |
Normalized | Grain refinement of the cast structure; intermediate strength without the cost of quenching large sections. | 500 | 830 | 10 | 23 HRC | 7.8 % IACS |
Normalized and tempered | Economical route for very heavy or complex castings where through-quenching is impractical. | 530 | 790 | 13 | 21 HRC | 7.8 % IACS |
quenched and high-temperature tempered (soft) | Pick when toughness and machinability matter more than strength, or when the part is later surface hardened elsewhere. | 560 | 750 | 17 | 19 HRC | 7.8 % IACS |
Stress relieved | Sub-critical soak after weld repair or heavy roughing to stabilise dimensions without changing hardness much. | 650 | 860 | 14 | 25 HRC | 7.8 % IACS |
QT-240-280HBDefault quenched and tempered (standard ) | Standard supply condition for gear blanks, ring gears and heavy machine castings needing balanced strength and toughness. | 680 | 880 | 13 | 26 HRC | — |
Q&T + induction/flame surface hardened | Tough Q&T core with a 50–56 HRC hardened skin on gear teeth, journals or track surfaces. | 680 | 880 | 12 | 54 HRC | 7.8 % IACS |
quenched and tempered (high strength) | Chosen for higher contact/bending load capacity in gear rims and rolls where some ductility can be traded away. | 780 | 980 | 11 | 31 HRC | — |
quenched and low-temperature tempered | Maximum through-hardness for wear-loaded castings; impact toughness and weld repairability become marginal. | 900 | 1,100 | 8 | 36 HRC | — |
What is ZG42CrMo?
ZG42CrMo is a higher-carbon chromium-molybdenum cast steel, the cast equivalent of wrought 42CrMo, used where cast parts need higher strength and hardenability than ZG35CrMo. In the default condition it reaches 680 MPa yield, 880 MPa tensile, 13 % elongation and 260 HB (26 HRC) with service to 400 °C, and is available in Q&T bands from 200–240 HB to 320–360 HB plus induction-hardened variants. The higher carbon makes it cold-crack sensitive: welding needs 250–350 °C preheat and PWHT, and the alloy is hot-tear sensitive in heavy sections. Choose ZG35CrMo where welding or toughness matters more than strength. ZG42CrMo has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F). ZG42CrMo has a yield strength of 680 MPa (98.6 ksi) and a tensile strength of 880 MPa (128 ksi) — stronger than 80% of steel grades. Elongation at break is 13% and the elastic modulus is 210 GPa (30.5 Msi).
What is ZG42CrMo used for?
- Gears
- Crankshaft supports
- High-strength machine bases
Advantages
- High strength — 680 MPa (98.6 ksi), better than 80% of steel grades
Limitations
- Limited formability — 10/100, worse than 95% of steel grades
- Limited ductility — 13%, worse than 78% of steel grades
ZG42CrMo properties
Typical room-temperature values for ZG42CrMo-QT-240-280HB; bars are the position among steel grades.
Physical3
ZG42CrMo has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
ZG42CrMo has a yield strength of 680 MPa (98.6 ksi) and a tensile strength of 880 MPa (128 ksi) — stronger than 80% of steel grades. Elongation at break is 13% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
ZG42CrMo is rated for continuous service to 400°C (752 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical2
ZG42CrMo has an electrical resistivity of 2.2×10⁻⁷ Ω·m.
Chemical & Environmental2
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of ZG42CrMo takes about 24 MJ of energy and emits 2 kg of CO₂ — less than 97% of steel grades. Typical recycled content is 75%.
Manufacturability8
ZG42CrMo's machinability is fair (45/100, worse than 65% of steel grades); weldability poor (30/100); formability not recommended (10/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. ZG42CrMo is highlighted; hover a dot for its name, or open the interactive family chart.
Working with ZG42CrMo
Is ZG42CrMo easy to machine?
Machine in annealed or 200–280 HB Q&T condition with rigid setups, coated carbide and moderate speeds; expect abrasive scale and sand inclusions on as-cast skin — take a heavy first cut.
Can ZG42CrMo be welded?
Weldable only with care: preheat 250–350 °C, low-hydrogen or matching Cr-Mo consumables, maintain interpass temperature and follow with 600–650 °C PWHT to avoid cold cracking.
Can ZG42CrMo be formed, bent or molded?
Sand or investment cast with generous fillets, chills and risers on heavy sections; alloy is hot-tear sensitive and needs homogenising/normalising to break down the as-cast dendritic structure.
ZG42CrMo 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 |
|---|---|---|
| Ccast equivalent of 42CrMo | 0.38 – 0.45 | 0.42 |
| Si | 0.2 – 0.6 | 0.4 |
| Mn | 0.5 – 1 | 0.75 |
| Cr | 0.8 – 1.2 | 1 |
| Mo | 0.15 – 0.3 | 0.22 |
| Niresidual, often restricted | ≤ 0.4 | |
| P | ≤ 0.03 | 0.02 |
| S | ≤ 0.03 | 0.02 |
| Fe | balance |
What surface finishes work on ZG42CrMo?
No anodizing; use shot blast plus paint, phosphate, black oxide, zinc or hard-chrome plating, and induction hardening plus grinding on wear surfaces.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Black / Phosphate
Thermal Spray
How much does ZG42CrMo cost?
ZG42CrMo is a standard-cost steel ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
ZG42CrMo — frequently asked
What is ZG42CrMo used for?
ZG42CrMo is typically used for gears, crankshaft supports and high-strength machine bases. In short: highest strength Cr-Mo casting; cast equivalent of 42CrMo; deep-hardening cast steel.
What is the yield strength of ZG42CrMo?
ZG42CrMo has a typical yield strength of 680 MPa (98.6 ksi) and a tensile strength of 880 MPa (128 ksi) — stronger than 80% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is ZG42CrMo easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% of steel grades). Machine in annealed or 200–280 HB Q&T condition with rigid setups, coated carbide and moderate speeds; expect abrasive scale and sand inclusions on as-cast skin — take a heavy first cut.
Can ZG42CrMo be welded?
Not readily — weldability is rated poor (30/100). Weldable only with care: preheat 250–350 °C, low-hydrogen or matching Cr-Mo consumables, maintain interpass temperature and follow with 600–650 °C PWHT to avoid cold cracking.
What surface finishes work on ZG42CrMo?
No anodizing; use shot blast plus paint, phosphate, black oxide, zinc or hard-chrome plating, and induction hardening plus grinding on wear surfaces.
Can ZG42CrMo be formed, bent or molded?
Sand or investment cast with generous fillets, chills and risers on heavy sections; alloy is hot-tear sensitive and needs homogenising/normalising to break down the as-cast dendritic structure.
What is the maximum service temperature of ZG42CrMo?
ZG42CrMo 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 ZG42CrMo QT-240-280HB and ZG42CrMo-A?
QT-240-280HB is the default condition — standard supply condition for gear blanks, ring gears and heavy machine castings needing balanced strength and toughness. A: softest condition for heavy rough machining or to relieve casting stresses before final quench and temper. Yield strength is 680 MPa in QT-240-280HB versus 380 MPa in A.
How much does ZG42CrMo cost?
ZG42CrMo is a standard-cost steel ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- GB/T 3077 (42CrMo wrought reference) — SAC (2015)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels, and High-Performance Alloys (Cast Low-Alloy Steels) — ASM International (1990)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.