Steel G42CrMo4 +A (Annealed)
Heat-treated state
EN 1.7231 · GB ZG42CrMo
Pick for rough-machining or when the casting will be heat treated after machining.
Values for the +A condition
Other G42CrMo4 tempers and conditions
G42CrMo4 is listed in 4 conditions; see the grade overview at G42CrMo4.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
+AThis page Annealed | Pick for rough-machining or when the casting will be heat treated after machining. | 380 | 640 | 20 | 195 HB | — |
Normalized | Intermediate strength with uniform structure in very heavy sections where through-quenching is impractical. | 450 | 700 | 16 | 18 HRC | 7.8 % IACS |
+QT1Default Quenched and tempered, lower strength class | Standard stocked condition: best balance of 500 MPa-class yield strength and impact toughness for general machinery castings. | 540 | 780 | 14 | 21 HRC | — |
Quenched and tempered, higher strength class | Choose when 700 MPa-class yield strength is required and section sizes are moderate; toughness and weld repairability drop. | 740 | 920 | 11 | 29 HRC | — |
What is G42CrMo4 +A?
G42CrMo4 +A is G42CrMo4 heat treated to +A — pick for rough-machining or when the casting will be heat treated after machining. G42CrMo4 +A has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 640 MPa (92.8 ksi) — weaker than 68% of steel grades. Elongation at break is 20% and the elastic modulus is 210 GPa (30.5 Msi). G42CrMo4 +A 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). +QT1 is the default condition FabDigit quotes; +A is available on request or by drawing note.
Advantages
- High service temperature — 450°C (842 °F), better than 86% of steel grades
Limitations
- Limited formability — 10/100, worse than 95% of steel grades
G42CrMo4 +A properties
Typical room-temperature values for G42CrMo4 +A; 10 are specific to this condition. Other listed values are G42CrMo4 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
G42CrMo4 +A 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
G42CrMo4 +A has a yield strength of 380 MPa (55.1 ksi) and a tensile strength of 640 MPa (92.8 ksi) — weaker than 68% of steel grades. Elongation at break is 20% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
G42CrMo4 +A is rated for continuous service to 450°C (842 °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).
Electrical3
G42CrMo4 +A conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (15/100), better than 75% of steel grades.
Sustainability4
Producing a kilogram of G42CrMo4 +A takes about 30 MJ of energy and emits 2.2 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 80%.
Manufacturability8
G42CrMo4 +A's machinability is good (58/100, better than 75% of steel grades); weldability fair (40/100); formability not recommended (10/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with G42CrMo4 +A
Is G42CrMo4 easy to machine?
Machine in the annealed state where possible; at 250–300 HB use rigid setups, coated carbide, moderate speed and heavy positive feed to break through the cast skin and any residual scale.
Can G42CrMo4 be welded?
Weldable only with care: preheat 250–350 °C, low-hydrogen or matching Cr-Mo consumables, controlled interpass temperature and a post-weld temper below the original tempering temperature; foundry weld repair is normally done before final heat treatment.
Can G42CrMo4 be formed, bent or molded?
Sand or investment cast with generous risering and directional solidification; avoid abrupt section changes, and stress-relieve before final heat treatment to limit distortion and quench cracking.
What surface finishes work on G42CrMo4?
No anodizing — protect with paint, phosphate, black oxide, zinc or hard chrome; induction or nitride hardening of journals is common on Q&T castings.
G42CrMo4 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 |
|---|---|---|
| CEN 10293 cast analysis | 0.38 – 0.45 | 0.42 |
| Si | ≤ 0.6 | 0.4 |
| Mn | 0.6 – 1 | 0.8 |
| P | ≤ 0.03 | — |
| S | ≤ 0.02 | — |
| Cr | 0.8 – 1.2 | 1 |
| Mo | 0.15 – 0.3 | 0.22 |
| Niresidual | ≤ 0.4 | — |
| Fe | balance | — |
G42CrMo4 +A — frequently asked
What is G42CrMo4 +A used for?
G42CrMo4 +A is typically used for gear and shaft castings, high-strength machinery components and heavy structural castings. In short: cast 4140 equivalent; highest strength cast CrMo; hardenable to 250–300 HB.
What is the yield strength of G42CrMo4 +A?
G42CrMo4 +A has a typical yield strength of 380 MPa (55.1 ksi) and a tensile strength of 640 MPa (92.8 ksi) — weaker than 68% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is G42CrMo4 +A easy to machine?
Reasonably — machinability is rated good (58/100, better than 75% of steel grades). Machine in the annealed state where possible; at 250–300 HB use rigid setups, coated carbide, moderate speed and heavy positive feed to break through the cast skin and any residual scale.
Can G42CrMo4 +A be welded?
With care — weldability is rated fair (40/100). Weldable only with care: preheat 250–350 °C, low-hydrogen or matching Cr-Mo consumables, controlled interpass temperature and a post-weld temper below the original tempering temperature; foundry weld repair is normally done before final heat treatment.
What surface finishes work on G42CrMo4 +A?
No anodizing — protect with paint, phosphate, black oxide, zinc or hard chrome; induction or nitride hardening of journals is common on Q&T castings.
Can G42CrMo4 +A be formed, bent or molded?
Sand or investment cast with generous risering and directional solidification; avoid abrupt section changes, and stress-relieve before final heat treatment to limit distortion and quench cracking.
What is the maximum service temperature of G42CrMo4 +A?
G42CrMo4 +A 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.
Sources
- EN 10293 — Steel castings for general engineering uses — CEN (2015)
- EN 10340 — Steel castings for structural uses — CEN (2007)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels and High-Performance Alloys — ASM International (1990)
- Steel Castings Handbook, 6th ed. — Steel Founders' Society of America / ASM (1995)
- Machinery's Handbook (machinability ratings) — Industrial Press (2020)
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.