Steel Investment Casting: Grades, Characteristics and Applications

For precise and versatile metal parts, steel investment casting is a fundamental manufacturing method used in a wide range of industries. Investment casting, known for its ability to produce complex shapes with excellent surface finishes, involves creating a wax model of the desired part, which is then encased in a ceramic shell to form a mold. After the wax is melted away, molten steel is poured into the mold, resulting in a part that maintains tight tolerances and possesses superior mechanical properties.

Steel investment casting offers versatility with various steel alloys for different applications. In this article, we’ll discuss steel grades, their properties, and their use in industries like automotive and aerospace, demonstrating the method’s value for precision and strength.

Grades of Steel Used in Investment Casting

Steel investment casting is a versatile manufacturing process to produce precision components across various industries. The selection of steel grade significantly impacts the properties and suitability of the final investment casting components.

Carbon Steel

Carbon steel investment castings are favored for its strength and cost-effectiveness, making it a popular choice for many general applications. Visit our carbon steel casting services page to find out more information if you require any carbon steel investment castings to be made.

• Low Carbon Steel (e.g., AISI 1020, 1025): These steels contain less than 0.3% carbon and are known for their excellent ductility and toughness. They are typically used for parts that require good weldability and are subject to moderate stress.
• Medium Carbon Steel (e.g., AISI 1045, 1050): With carbon content ranging from 0.3% to 0.6%, these steels offer a balance between strength and ductility. They are suitable for parts like levers, bolts, and general machinery components.
• High Carbon Steel (e.g., AISI 1060, 1095): High carbon steels contain more than 0.6% carbon and are used for their hardness and wear resistance in products like springs and high-strength wires.

Alloy Steel

Alloy steel investment castings are enhanced with various alloying elements to improve their mechanical properties and are used for more demanding applications.

• Low-Alloy Steel (e.g., AISI 4130, 4140): These steels are strengthened with elements like chromium and molybdenum to offer higher tensile strength and toughness. They are ideal for components in the automotive and aerospace sectors.
• High-Alloy Steel (e.g., AISI 8620, 4340): These grades contain a higher percentage of alloying elements, providing superior strength and heat treatability. They are used for high-performance gears, fasteners, and aircraft landing gear.

We specialize in custom alloy steel investment castings. Visit our alloy steel casting service page to learn more about our capabilities. For information on alloy steel casting grades, properties, and applications, please visit our alloy steel castings blog page.

Stainless Steel

Known for its corrosion resistance, stainless steel investment castings are used in applications that require exposure to corrosive environments or high levels of hygiene.

• Austenitic Stainless Steel (e.g., AISI 304, 316): These are non-magnetic steels containing high levels of chromium and nickel. Grade 304 is highly corrosion-resistant and weldable, making it suitable for kitchen equipment, auto parts, and medical devices. Grade 316 includes molybdenum, enhancing its corrosion resistance against chlorides, thus perfect for marine and chemical processing equipment.
• Martensitic Stainless Steel (e.g., AISI 410, 440C): These are magnetic steels known for their hardness and high strength, used in cutlery, pump shafts, and turbine parts.
• Precipitation Hardening Stainless Steel (e.g., 17-4 PH): This group offers both high strength and good corrosion resistance, making it ideal for aerospace and other structural applications.

For a more in depth look into Stainless steel investment casting grades, properties and applications, please read our Stainless Steel Investment Casting Grades, Characteristics and Applications blog post.

Characteristics of Steel Used in Investment Casting

The steel used in investment casting possesses unique characteristics that make it suitable for a wide range of applications, ensuring that components meet the stringent demands of various industries.

Strength and Durability: Steel is highly valued in investment casting for its intrinsic strength and durability. The ability of steel to withstand significant stress and strain without failing makes it suitable for critical structural components in automotive, aerospace, and industrial machinery. This durability ensures that the investment castings perform under severe conditions and have a long service life.

Malleability and Ductility: Despite its strength, steel is also malleable and ductile, which allows it to be molded into complex shapes without losing its toughness. This is particularly beneficial in investment casting, where intricate designs and precise dimensional tolerances are required. The ductility of steel also means that it can deform under stress without fracturing, which is crucial for components that experience cyclic loading.

Corrosion Resistance: Stainless steel alloys used in investment casting are chosen for their excellent corrosion resistance. These alloys contain chromium, which forms a passive layer of chromium oxide on the surface, protecting the steel from various corrosive environments. This property is essential for parts used in marine, chemical processing, and medical applications where resistance to corrosion significantly extends the life of the products.

Weldability and Machinability: Steel’s weldability and machinability are critical factors that an investment casting company considers during the manufacturing process. Steel’s compatibility with welding means that larger structures can be fabricated from smaller cast parts, providing flexibility in design and application. Moreover, the machinability of steel allows for fine finishes and precise adjustments post-casting, which are often required to achieve the final specifications of the casting.

Heat Treatability: One of the significant advantages of steel in investment casting is its heat treatability. Heat treatments such as annealing, quenching, and tempering can alter the microstructure of steel, enhancing its mechanical properties such as hardness, strength, and resistance to wear. This adaptability allows investment casting companies like Taiyuan Simis to tailor the properties of the steel to match the specific needs of an application, optimizing performance and efficiency.

Applications of Steel Investment Castings

Steel investment castings are integral to numerous industrial applications due to their strength, precision, and versatility. The ability to cast steel into complex shapes while maintaining high strength and integrity allows for its widespread use across various sectors.

Automotive Industry

In the automotive sector, steel investment castings are used for parts that require high strength and durability under extreme operational conditions. Common applications include gearbox components, engine brackets, steering knuckles, shifting forks, pistons, and various suspension components. These parts benefit from steel’s robustness and wear resistance, enhancing vehicle reliability and performance.

Aerospace and Aviation

The aerospace industry demands components that can withstand high stresses and function flawlessly in critical environments. Steel investment casting is used to manufacture engine components, landing gear parts, and airframe structural elements. The high strength-to-weight ratio of certain steel alloys makes them ideal for such applications, ensuring safety and efficiency in aerospace engineering.

Energy Sector

Steel investment castings play a crucial role in the energy industry, especially in oil and gas extraction and power generation. Components such as valve bodies, turbine blades, and pump housings, cross coupling clamps are commonly produced using steel casting. These parts require excellent mechanical properties and corrosion resistance to withstand the harsh conditions typical in energy production environments.

Medical Equipment

Although less common than in other industries, steel investment castings are used in the medical field for surgical instruments and orthopedic implants. Stainless steel, known for its corrosion resistance and biocompatibility, is particularly favored for such applications, ensuring patient safety and long-term durability.

Construction and Mining Machinery

The construction and mining sectors rely on heavy-duty machinery that must endure abrasive environments and continuous use. Steel investment casting is used to produce structural components for heavy equipment, including excavator teeth, crane hooks, and ground-engaging tools. The high impact resistance and hardness of steel make it suitable for these demanding applications.

General Engineering: For general engineering applications, steel investment castings are used in creating complex mechanical parts such as gears, couplings, and connectors. These components benefit from steel’s excellent machinability and the precision of the investment casting process, which allows for the production of highly detailed and specific parts.

Marine Applications: In the marine industry, stainless steel investment castings are essential for their resistance to saltwater corrosion. Typical uses include propellers, deck hardware, and housing components that must perform reliably in corrosive marine conditions.

Advantages of Steel Investment Casting

Steel investment casting offers numerous advantages that make it a preferred manufacturing method across various industries. This process enables the production of steel castings with exceptional precision, integrity, and versatility.

Complex Geometries and Detailed Precision: One of the standout advantages of steel investment casting is its ability to produce components with complex shapes and intricate details. This process can achieve tight tolerances and excellent surface finishes, which are often unattainable with other casting methods. The dimensional accuracy and high resolution of details in steel castings make this process ideal for components that require precise internal features or complex external shapes.

High Material Integrity: Steel investment castings produced through this process exhibit superior mechanical properties, including strength, ductility, and toughness. The casting process allows minimal internal defects, such as porosity or inclusions, which in turn enhances the structural integrity of the parts. This makes steel investment casting particularly valuable for critical applications in the aerospace, automotive, and industrial sectors, where component failure could have severe implications.

Versatility in Applications: The versatility of steel alloys used in investment casting allows manufacturers to customize materials to specific application needs. Whether it’s stainless steel for corrosion resistance in marine environments or carbon steel for high strength in construction equipment, steel investment casting can accommodate a wide range of properties to meet diverse operational demands.

Efficiency and Cost-Effectiveness: Despite the high precision and quality of steel castings, investment casting remains a cost-effective production method, especially for medium to high-volume productions. The ability to produce near-net-shape parts reduces the need for extensive machining and material wastage, leading to significant cost savings in both raw materials and labor.

Excellent Surface Finish: Steel investment castings generally require minimal surface finishing due to the smooth surfaces achieved through the casting process. This not only reduces additional processing costs but also improves the aesthetic appearance of the parts, which can be crucial for consumer-facing applications.

Flexibility with Size and Weight: The investment casting process is adept at handling a wide range of part sizes and weights, making it suitable for everything from small complex components to larger castings used in heavy machinery. This flexibility allows manufacturers to use steel investment casting for a broad spectrum of products without the need for multiple manufacturing techniques.

If you would like to learn more about the investment casting process and its advantages, we recommend you check out our industry-leading investment casting process page.

Conclusion

Taiyuan Simis Investment Casting Co., Ltd is a professional investment casting manufacturer in China, our dedication to excellence in steel investment casting has positioned us as a leader in the foundry industry, particularly within the competitive landscape of China’s investment casting sector. With custom investment casting services tailored to accommodate a variety of steel grades and complex requirements, we guarantee that our clients receive only the highest quality, precision-engineered castings. Our ability to offer an all-in-one supply service—from rapid prototyping and in-house tooling to advanced CNC machining, surface finishing, heat treatment, as well as testing and inspection—sets us apart as a full-service provider.

For those who require precision, reliability, and quality in steel investment castings, Taiyuan Simis is your trusted partner. Contact us today to learn more about how our services can enhance the success of your steel investment casting projects and provide you with the competitive edge you need in the market.