4140 is a low-alloy steel containing chromium and molybdenum. Heat treatment gives it high strength and wear resistance, so it is widely used in demanding parts. Investment casting produces this steel in complex shapes with less machining.
The Cast Equivalent of 4140
4140 is a wrought steel designation (EN equivalent 42CrMo4, 1.7225). For castings, the European grade with similar chemistry is G42CrMo4 (1.7231) under EN 10293.
| Element | G42CrMo4 typical range |
|---|---|
| Carbon | 0.38–0.45% |
| Chromium | 0.8–1.2% |
| Molybdenum | 0.15–0.30% |
| Manganese | 0.6–1.0% |
The standard named on your drawing governs the order.
Heat Treatment Decides the Result
The mechanical properties of 4140 depend heavily on heat treatment. Parts are usually quenched and tempered to reach the required hardness and strength, so the drawing should state the target hardness or mechanical values. Distortion during heat treatment should be considered at the design stage for long, thin parts.
Why Investment Cast 4140?
- Complex geometry can be produced as one piece.
- Less machining means less material waste.
- Dimensions stay more consistent across repeat orders.
- Machining only functional surfaces can reduce part cost.
Typical Applications
Cast 4140 is used in machine components, mechanism parts, gears, levers and firearm parts. Welding may need preheating because of the carbon content. Where welding is the priority, a low-carbon steel may suit better.
4140 Casting at BRK Metal
4140 is one of BRK Metal’s main alloys. We cast parts from 1 g to 25 kg to customer drawings. See our steel investment casting page or send us your drawing.