FAQs about Steel Investment Casting
This blog is part of our Foundry 101 series, covering some of the most frequently asked questions about the materials, processes, and equipment used in an Investment Casting Foundry. Today, we'll discuss FAQs about low-alloyed steel castings, and while doing so, touch on material basics, frequently poured metals, usage scenarios, pros and cons of these materials, secondary operations, and more.
Without further ado, let's get into it!
A 4140 Steel Casting. Notice the surface finish and geometry achieved without machining.
What is Low-Alloyed Steel
Low-alloyed steel typically refers to any steel where additive metals (alloys) represent less than ~5% of the total composition; this is in contrast to materials like Stainless Steel, where alloy content is higher (stainless steels contain a minimum of 10.5% chromium among other alloys).
* Note, some consider low-alloyed steels to include materials including alloys up to ~12% of the total composition. This inclusion is a byproduct of some materials with higher alloy content behaving more similarly to low-alloyed steels than stainless steel, as well as some specialized materials distinguishing themselves from other high-alloy content materials (like stainless). The exact nuances of this delineation are beyond the scope of this article, but we want to note that some materials sit on the borderline between low-alloy and high-alloyed steels. If you have any specific material questions, contact our team!*Low-alloyed steel (hereafter referred to as steel) provides a good balance of strength, toughness, hardness, and wear resistance - while maintaining good weldability and machinability. Its lower-alloy content often makes it considerably cheaper to cast, solidifying it as a go-to material type for hundreds of industries.
What Are the Key Characteristics of Steel?
Carbon Content: is generally less than 0.25%, making them more weldable and ductile than high-carbon steels.
Mechanical Properties: Good hardenability, strength, wear resistance, toughness, and ductility.
Heat Treatable: Often used in applications where heat treatment is needed to enhance performance. The flexibility afforded by heat treatment options allows it to attain a range of toughness and strength values.
Machinable: Low-alloyed steels are typically machinable.
Secondary Treatments: Can be heat treated with different methods to achieve different tensile, yield, elongation, and hardnesses with the same base as-cast chemical composition
Alloying elements typically include:
Chromium (Cr): Increases hardness, wear & corrosion resistance
Nickel (Ni): Adds toughness/impact resistance
Molybdenum (Mo): Improves hardenability and high-temp strength
Manganese (Mn): Increases strength & hardenability
Vanadium (V): Refines grain structure and improves fatigue resistance
Silicon (Si): Strengthens ferrite, improves oxidation resistance
What are Your Most Commonly Cast Steels?
IPC casts over 100 materials and served over 130 different industries in 2024. Our most commonly poured steels (low-alloyed) are:
1020 steel
1030 steel
1050 steel
4130 steel
4140 steel
4320 steel
4340 steel
8620 steel
25CrMo4
What are Common Uses for Low-Alloyed Steel Castings?
Low-alloyed steel castings are ubiquitous because of their material properties (strength, toughness, wear resistance, etc.) and cost-efficiency when compared to materials like stainless steel or tool steels.
Here are just a few common usage scenarios:
1. Construction & Heavy Equipment
Structural components (beams, joints)
Lifting hooks, crane parts
Excavator arms and buckets
Bulldozer blades and undercarriage parts
2. Automotive & Transportation
Axles and axle housings
Suspension arms
Differential cases
Gearboxes and brackets
Truck and trailer frame components
3. Oil & Gas Industry
Valve bodies
Pump housings
Drill bits and downhole tools
Pipe connectors and flanges
Casing heads
4. Mining & Earthmoving
Crusher hammers and liners
Shovel teeth
Conveyor links
Track shoes
5. Power Generation
Steam turbine housings
Boiler components
Pump and motor casings
Structural frames for generators
6. Agriculture
Tractor parts
Harvester linkages
Gear cases
Tillage components
7. Rail & Marine
Rail couplers
Brake shoes and levers
Marine hardware and rudder parts
Propeller hubs
8. Sports & Recreation Equipment
Cast frames for gym machines
Weight stack components
Off-road vehicle (ATV/UTV) suspension brackets
Motorcycle fork yokes and engine mounts
Pros and Cons of Low-Alloy Steel Castings
Low-alloy steel castings offer an excellent balance of performance and cost, but they also have their limitations. Here are some pros and cons of low-alloyed steel:
✅ Advantages (Pros)
1. Desirable Mechanical Properties
Higher strength & toughness than carbon steel due to alloying elements (Cr, Ni, Mo, V).
Better wear resistance – Ideal for high-stress components like gears, shafts, and mining equipment.
Improved fatigue resistance – Suitable for cyclic loading (e.g., automotive and aerospace parts).
2. Good Heat Treatment Response
Can be quenched & tempered to achieve desired hardness (e.g., 4140 and 4340 steels are classic examples of this).
Hardenability is better than carbon steel, allowing deeper hardening.
3. Cost-Effective for Complex Shapes
Near-net-shape casting reduces machining costs compared to forging.
Lower tooling costs than die casting for small-to-medium batches.
4. Versatility
Found in everything from home goods, medical equipment, outdoor equipment, engineering/structural equipment, and much more
Works in high-pressure, high-temperature environments (e.g., oil & gas valves, power plant components).
Used in critical structural parts (e.g., military armor, heavy machinery).
5. Better Corrosion & Oxidation Resistance Than Carbon Steel
Alloys like Cr and Mo improve resistance to oxidation and mild corrosive environments.
❌ Disadvantages (Cons)
1. Higher Cost Than Carbon Steel
Alloying elements (Ni, Cr, Mo) increase material costs.
More expensive heat treatment may be required.
2. Limited Corrosion Resistance in Harsh Environments
Not suitable for seawater or acidic conditions (stainless steel, coatings, or different materials are needed).
Prone to rust if unprotected (requires painting or plating).
3. Not Ideal for Extreme Temperatures
Above ~600°C (1112°F), creep resistance drops (high-alloy steels are better).
Low-temperature brittleness can be an issue (unless Ni-alloyed for cryogenic use).
When to Choose Low-Alloy Steel Castings?
Low-alloy steel castings are an excellent middle-ground solution for demanding mechanical applications where carbon steel falls short but stainless steel (or another high-alloy option) is overkill. Low-alloy steels benefit from proper heat treatment, welding controls, and quality checks, all of which are key to maximizing performance. For any casting project, it is critical to find the performance you need while staying on budget. If you have questions about materials for your next casting project, don't hesitate to contact our team!
Conclusion:
In this blog, we've explored some of the basics of low-carbon steel by addressing some of our most frequently asked questions. Low-carbon steels are a popular choice for precision casting projects because of their unique blend of strength, wear resistance, toughness, hardenability, and cost-effectiveness. We've also explored dozens of examples of low-alloyed steels in action.
If you're interested in utilizing these materials in your next project, IPC Foundry Group would love to be your production partner. We're built to tackle any project with two modernized investment casting foundries and over 100 materials on offer - suited for any application. Contact our team today to see how we can save you time and money on your next project!
