Stainless Steel Casting Guide | Processes, Steps, Grades, Castings & Suppliers

Stainless steel casting is a flexible and widely used manufacturing process that forms a variety of durable, corrosion-resistant and precision stainless steel components by pouring molten stainless steel into a mold. We will give you a comprehensive introduction to stainless steel casting, covering various casting processes, casting steps, casting influencing factors and standards, casting applications, etc., and comparing stainless steel castings with other materials.

What is Stainless Steel Casting?

Stainless steel casting is a metal processing process that uses molten stainless steel materials to shape through molds and cool and solidify into the desired shape and size. It can produce stainless steel castings of various sizes with corrosion resistance, heat resistance and high strength, and is widely used in many industries such as construction, chemical industry, and food processing.

Is Stainless Steel Good for Casting?

Yes, stainless steel is good for casting, particularly for producing complex shapes and components. Casting allows for intricate designs that may be difficult to achieve with other methods. However, it’s important to note that cast stainless steel may have some inherent defects, such as porosity or inclusions, which can affect its mechanical properties.

Casting Stainless Steel Classification

Corrosion Resistant Castings

Tailored for highly corrosive environments, they are widely used in chemical equipment, marine equipment, and food processing machinery to ensure long-term stable operation.

Heat Resistant Castings

Designed for extremely high-temperature environments, they are commonly found in gas turbines, boiler systems, and various industrial furnaces. These castings are rich in carbon and chromium, which significantly improves their strength and stability under high-temperature conditions, ensuring excellent performance and durability of the equipment.

Precision Castings

Used in applications requiring high dimensional accuracy and surface finish, such as aerospace, medical devices, and high-precision mechanical parts.

Structural Castings

Used in architectural and engineering structures to provide high strength and durability, such as bridges, building supports, and mechanical structures.

What Is the Casting Method for Stainless Steel?

Investment Casting

Investment casting, also named as lost wax casting, first makes a wax pattern, then covers it with a ceramic shell, leaving a void of melted wax, and then injects stainless steel. This method is known for its high precision, complex shapes and smooth surfaces. It is often used to produce parts that require high precision and complex shapes, such as aerospace and medical devices.

Centrifugal Casting

Molten stainless steel is poured into a rotating mold, and centrifugal force causes the metal to adhere to the wall and solidify, forming a uniform and dense casting. Suitable for cylindrical parts, such as pipes and rings, and widely used in the chemical and petroleum industries.

Continuous Casting

Continuous casting involves pouring molten stainless steel into a continuous mold, and the metal gradually solidifies as the mold moves on a conveyor belt. This method efficiently produces long, uniform stainless steel sections such as bars, rods, and plates. Continuous casting is widely used in the steel manufacturing industry because it is able to produce large quantities of steel at a high efficiency.

Sand Casting

Sand casting uses sand mixed with a binder to make a mold, into which molten stainless steel is poured and solidified to form a casting. Sand casting is flexible and cost-effective, suitable for producing large parts and small batches. It is widely used to make large-sized, simple-shaped castings such as machine tool beds, engine blocks, etc.

Corner Casting

Corner casting is a specialized technique used to create parts with complex geometries, especially those with sharp corners and intricate details. This method often combines sand casting and investment casting techniques to achieve the desired results. It is typically to produce structural components that have high strength and precise dimensions, such as building and bridge components.

Pressure Die Casting

Pressure casting involves pouring molten stainless steel into a mold under high pressure. This method is very efficient for large-scale production and is able to produce parts with extremely high dimensional accuracy and smooth surfaces. For the automobile industry, it is widely used to manufacture engine parts and other high-precision parts.

What Temperature Is Needed for Stainless Steel Casting?

The temperature required for stainless steel casting typically ranges between 2500°F to 2700°F (about 1370°C to 1480°C). This high temperature is necessary to melt the stainless steel and ensure it flows properly into molds. The exact temperature can vary depending on the specific alloy and casting method used.

Related Reading
Stainless Steel Melting Temperature

How to Cast Stainless Steel?

The stainless steel casting process includes multiple steps to ensure that high-quality parts are produced.

Model creation

A wax or foam model of the desired part is created using a precision mold. The accuracy of the model directly affects the quality of the final casting, so advanced 3D modeling and printing technologies are often used to make the model.

Mold preparation

According to the casting process and the characteristics of the casting, the appropriate mold material, such as aluminum, gypsum or ceramic, is selected, and then the mold is prepared by coating the ceramic shell or embedding the model in the sand. The selection and production of the mold are directly related to the success or failure of the subsequent casting.

Lost wax

In the investment casting process, the wax model is placed in a high temperature environment using the lost wax technology to completely melt and discharge it, leaving a precise cavity inside the mold. This process ensures the purity of the mold and the high precision of the casting.

Melting

Place the stainless steel raw material in a high-temperature furnace and strictly control the temperature conditions to ensure that the metal is completely melted and reaches the ideal purity, laying the foundation for subsequent pouring operations.

Pouring

Under strict monitoring, the high-temperature molten stainless steel liquid is slowly poured into the prepared mold. This process requires careful operation to prevent bubbles and impurities from mixing, thereby ensuring the high quality of the casting.

Cooling

The stainless steel liquid naturally cools and solidifies in the mold to form a casting. The cooling speed and method affect the quality and need to be scientifically controlled to optimize performance.

Removing the mold

Break the mold to reveal the casting. This step requires careful operation to prevent damage to the casting.

Post-processing

The casting is subjected to a series of post-processing processes, including grinding, polishing, and heat treatment according to specific needs, to further improve its performance and surface finish. The selection and implementation of post-processing processes will directly affect the final quality of the casting.

Inspection

The post-processed casting is fully inspected, and a variety of methods such as non-destructive testing, dimensional measurement and surface quality assessment are used to ensure that the casting is defect-free and meets the established quality standards.

Common Grades of Stainless Steel Castings

304/304L

Known for excellent corrosion resistance and weldability, suitable for food processing and chemical equipment. 304L is a carbon-free version of 304 and is less susceptible to intergranular corrosion when welded.

316/316L

Provides excellent corrosion resistance, especially in chloride environments, suitable for marine and medical applications. 316L is a carbon-free version of 316 with better corrosion resistance.

410

A martensitic stainless steel with high strength and moderate corrosion resistance, used in valves and pumps. 410 steel can be heat treated to increase hardness and strength.

416

416 is a martensitic stainless steel known for excellent machinability and moderate corrosion resistance. It’s ideal for precision machining and applications like valves and pumps. While it offers good strength and wear resistance, its corrosion resistance is lower than austenitic grades like 304.

17-4 PH

A precipitation-hardening stainless steel known for high strength and hardness, suitable for aerospace and petrochemical applications. 17-4 PH steel can significantly improve mechanical properties through heat treatment and aging.

2205

A duplex stainless steel. 2205 steel combines the advantages of austenite and ferrite, with good plasticity and toughness, as well as high strength and corrosion resistance. Suitable for chemical and oil and gas industries.

What Is a 304 Stainless Steel Casting?

A 304 stainless steel casting is a component made by pouring molten 304 stainless steel into molds, allowing for complex shapes. This alloy, containing about 18% chromium and 8% nickel, offers excellent corrosion resistance and is commonly used in food processing and chemical applications, though it may have some porosity.

Can 316 Stainless Steel Be Cast?

Yes, 316 stainless steel can be cast. It’s often used in investment casting processes to create complex shapes and components.

Stainless Steel Casting Advantages

• Design flexibility: complex geometries and detailed parts can be produced. The casting process allows designers to freely create complex internal structures and unique appearances.

• Dimensional accuracy: The casting process is precise and can produce parts that meet specifications highly. Modern casting technology can achieve very small dimensional tolerances and meet high precision requirements.

• Mechanical property improvement: Through controlled cooling and post-processing processes, castings have excellent mechanical properties. Heat treatment and surface treatment can further enhance the strength, hardness and wear resistance of castings.

• Corrosion resistance: The casting process can ensure uniform distribution of materials and enhance corrosion resistance. Stainless steel castings are widely used in harsh environments and show excellent corrosion resistance.

• Cost-effectiveness: Despite the higher initial cost, the durability and low maintenance of castings make them a cost-effective choice. The casting process can reduce material waste and processing time, reducing overall costs.

Stainless Steel Casting Applications

Stainless steel castings are widely used in several industries.

Aerospace: Stainless steel castings are used in aircraft and turbines to enhance strength and heat resistance, improving flight safety.

Automotive: Stainless steel castings improve durability and corrosion resistance in engines and exhaust systems, extend vehicle life, and reduce maintenance costs.

Medical equipment: Used in surgical instruments and implants, providing biocompatibility and high strength. The application of stainless steel castings in the medical field can improve the safety and reliability of medical devices.

Food processing: Used in processing equipment and containers, providing easy cleaning and high corrosion resistance. The application of stainless steel castings in the food industry can ensure the hygiene and safety of food processing.

Chemical: Stainless steel castings are used in pipelines, reactors and storage tanks. They are resistant to corrosion and high temperatures, improve efficiency and reduce failures.

Construction: Used for structural support and decorative elements, providing beauty and durability. The application of stainless steel castings in the construction field can enhance the appearance and structural performance of buildings.

What Affects the Results of Stainless Steel Casting?

Alloy selection: Different alloys have different properties, such as melting point, fluidity and corrosion resistance. Choosing the right alloy is essential to ensure that the casting has ideal mechanical properties and durability.

Mold design: Exquisite mold design and high-quality material selection are essential for castings with high precision, smooth surface and excellent mechanical properties. Reasonable mold design can effectively avoid casting defects, improve production efficiency, and ensure that each process reaches the optimal state.

Pouring temperature: The pouring temperature of the molten metal affects its ability to fill the mold and solidify without defects. Too high or too low pouring temperature can cause casting quality problems.

Cooling rate: As a key parameter, the cooling rate directly affects the formation of the internal structure of the casting and the performance of mechanical properties. Controlling the cooling rate can optimize the internal structure of the casting and avoid defects such as hot cracks and shrinkage holes.

Post-treatment processes: including heat treatment, machining and surface treatment, which can significantly improve the final properties of castings. The correct post-treatment process can improve the strength, toughness and corrosion resistance of castings.

Stainless Steel Casting Defects and Solutions

During the stainless steel casting process, various defects may occur, which will affect the quality and performance of the castings. Understanding the causes and solutions of these defects can effectively improve the quality of castings and reduce the scrap rate.

1. Porosity

• Causes

Porosity is mainly caused by unreasonable mold design that prevents gas from being discharged smoothly, excessive gas in liquid metal, inappropriate pouring speed that causes gas to be mixed in the metal, and moisture in the mold material.

• Solutions

Optimize mold design to add vents to ensure smooth gas discharge, control pouring speed to a moderate level to avoid gas inclusions, use degassing treatment to reduce the gas content in liquid metal, and ensure that the mold material is completely dry before use.

2. Shrinkage and shrinkage

• Causes

Shrinkage and shrinkage are holes or loose areas formed by volume shrinkage of metal during solidification. The main reasons include unreasonable pouring system design, inappropriate pouring temperature, and uneven wall thickness of castings.

• Solutions

Design a reasonable pouring system to ensure that the molten metal can be replenished smoothly during solidification, control the pouring temperature to an appropriate range, and optimize the casting design to ensure uniform wall thickness.

3. Cracks

• Causes

Cracks usually occur during the cooling process of castings, mainly due to unreasonable casting design leading to stress concentration, excessive thermal stress due to excessive cooling speed, and insufficient material toughness due to inappropriate alloy composition.

• Solutions

Optimize casting design to reduce stress concentration areas, control cooling speed to make it uniform to avoid excessive cooling, and select appropriate alloy composition to improve material toughness.

4. Slag inclusion

• Causes

Slag inclusions refer to non-metallic impurities mixed in castings, mainly due to insufficient purification of molten metal, unreasonable design of pouring system, and improper operation during pouring, which leads to impurities entering the mold.

• Solutions

Strengthen the purification of molten metal, adopt appropriate refining and filtration technology, optimize the design of the pouring system to ensure that impurities can be discharged smoothly, and strictly control pouring operation to avoid impurities entering the mold.

5. Deformation

• Causes

Deformation of castings is caused by uneven stress during cooling. The main reasons include unreasonable casting design leading to uneven cooling, excessive cooling speed, and inappropriate pouring temperature.

• Solution

Optimize casting design to ensure uniform cooling process, control cooling speed to moderate to avoid too fast cooling, and adjust pouring temperature to keep it within the appropriate range.

6. Surface defects

• Causes

Surface defects include surface roughness, surface pores, cracks, etc., which are mainly caused by poor mold surface quality, inappropriate pouring speed, and impurities in the molten metal.

• Solution

Improve mold surface quality to ensure smooth mold surface, control pouring speed to moderate to avoid surface pores or cracks, and strengthen molten metal purification to reduce impurity content.

7. Segregation

• Causes

Segregation refers to the uneven distribution of alloy elements in castings, which is mainly caused by unreasonable pouring system design, inappropriate pouring speed and uneven cooling speed, which leads to the separation of alloy elements during solidification.

• Solution

Design a reasonable pouring system to ensure uniform flow of molten metal, control pouring speed to moderate to ensure uniform distribution of alloy elements, and optimize the cooling process to ensure uniform cooling speed.

Casting Surface Treatment Technology

Surface treatment technology can improve the appearance and performance of stainless steel castings.

Sandblasting: by blasting particles to remove surface impurities and improve texture. Sandblasting can enhance adhesion and improve coating effect.

Polishing: Mechanical polishing to obtain a smooth and bright surface. Polishing can improve the surface finish of castings and reduce friction and wear.

Electropolishing: Remove the surface layer through an electrochemical process to improve the surface finish and corrosion resistance. Electropolishing can improve the antibacterial and corrosion resistance of castings, suitable for medical and food industries.

Passivation: Using specific chemical methods to strengthen the natural passivation layer on the surface of castings, significantly enhancing its corrosion resistance. This process not only improves the oxidation resistance of castings, but also effectively extends the service life of castings.

Powder coating: Apply dry powder coating and cure in an oven to obtain a durable surface. Powder coating can improve the wear resistance and UV resistance of castings, suitable for outdoor applications.

Cast Stainless Steel vs Stainless Steel

The choice between cast and forged stainless steel depends on the specific requirements of the application, including complexity, strength, and cost considerations. They differ in:

1. Manufacturing Process

• Cast Stainless Steel: Made by pouring molten stainless steel into a mold, allowing it to cool and solidify into a specific shape. This process is suitable for complex geometries.
• Forged Stainless Steel: Created by heating stainless steel and then mechanically deforming it (hammering or pressing) to shape it. This process enhances the metal’s strength and grain structure.

2. Properties

• Cast Stainless Steel: Generally has a more uniform structure but may contain defects like porosity or inclusions, which can affect mechanical properties.
• Forged Stainless Steel: Typically exhibits superior strength, toughness, and fatigue resistance due to the refined grain structure achieved during forging.

3. Applications

• Cast Stainless Steel: Often used for intricate components, such as valves, fittings, and decorative items, where complex shapes are required.
• Forged Stainless Steel: Preferred for high-stress applications, such as in the aerospace, automotive, and structural industries, where reliability and strength are critical.

4. Cost

• Cast Stainless Steel: Usually more cost-effective for producing complex shapes in larger quantities.
• Forged Stainless Steel: Generally more expensive due to the labor-intensive process, but offers better performance in critical applications.

Stainless Steel Casting vs Cast Iron

• Stainless Steel Castings: Provide excellent corrosion resistance and mechanical properties. Suitable for demanding applications such as chemicals, food processing and medical equipment. Stainless steel castings perform well in high temperature and corrosive environments and have a longer service life.

• Cast Iron: Lower cost, excellent machinability and wear resistance. Suitable for applications requiring high wear resistance and dimensional stability, such as pipes, pumps and valves. Cast iron castings perform well in static load and low impact applications, but their corrosion resistance and toughness are lower.

Stainless Steel Castings vs Aluminum Castings

• Stainless steel castings: Known for their strength, corrosion resistance and high temperature performance, suitable for demanding applications. Stainless steel castings offer significant advantages in mechanical properties and durability, suitable for applications requiring high strength and long life.

• Aluminum castings: Offers better strength-to-weight ratio, easy machining, suitable for lightweight applications, such as aerospace and automotive components. Aluminum castings excel in weight-sensitive and corrosion-resistant applications, but their strength and high temperature performance are lower.

Further reading: Stainless Steel vs Aluminum.

What Are the Factors that Affect the Cost of Stainless Steel Casting?

Raw material cost: The price of stainless steel depends on its alloy composition and market demand fluctuations. The price fluctuations of alloying elements such as nickel, chromium and molybdenum will directly affect the cost of stainless steel.

Casting method: Different casting methods have different production efficiency and costs. For example, investment casting is usually more expensive but can produce parts with high precision and complex shapes, while sand casting is less expensive but suitable for larger and simpler castings.

Mold manufacturing: The design and manufacture of molds are important cost components in the casting process. Complex mold design and high precision requirements will increase the manufacturing cost of molds.

Processing and post-processing: Post-processing processes such as machining, heat treatment and surface treatment are included. These processes increase the total cost, but can significantly improve the quality and performance of castings.

Production batch: Large-scale production can usually reduce the cost per piece because the cost of molds and equipment can be amortized over more products. Small-scale production is more expensive because the fixed cost of each product is higher.

Quality control: Strict quality control measures, such as non-destructive testing and chemical analysis, although increasing costs, can ensure product quality and improve customer satisfaction.

Labor costs: The cost of human resources required in the manufacturing process, including wages and benefits for skilled workers.

Energy consumption: Energy use in the casting process, such as electricity and fuel, is also a key factor affecting costs. Melting and pouring metal requires a lot of energy, and energy price fluctuations will directly affect production costs.

Transportation and logistics: The transportation and logistics costs of castings also need to be considered, especially for large and heavy castings.

Stainless Steel Casting Quality Control and Standards

Stainless steel casting quality control

Material management: Ensure that the stainless steel raw materials meet the standards, strictly control the alloy composition, and perform melt purification.

Process control: Optimize the casting process, including parameters such as temperature, pouring speed, and pressure, to ensure the internal quality of the casting.

Molds and equipment: Use high-precision molds and regularly maintain casting equipment to ensure the stability and reliability of the production process.

Process monitoring: Real-time monitoring of the casting process, use non-destructive testing technology to check the quality of castings, and promptly discover and solve problems.

Casting standards

Stainless steel casting standards ensure the quality and performance of castings. Common standards include:

ASTM: American Society for Testing and Materials, provides a series of standards on stainless steel castings, such as ASTM A351, ASTM A743, etc.

ISO: International Organization for Standardization, has developed many international standards related to stainless steel casting, such as ISO 8062.

ASME: American Society of Mechanical Engineers, whose standards cover the design and manufacture of pressure vessels and boilers, including stainless steel castings.

EN: European standard, involving the chemical composition and mechanical property requirements of stainless steel castings, such as EN 10283.

How to Cast Metal at Home?

Materials Needed

For casting metal at home, you’ll need aluminum or bronze as the metal, a propane or charcoal furnace, a crucible for holding the molten metal, and molds made of sand, clay, or metal. Ensure you have safety gear like heat-resistant gloves, safety goggles, and a face shield, along with tools such as tongs, a ladle, a hammer, and a metal file.

Step-by-Step Process

Start by designing your mold based on the shape of the object you want to cast. Prepare the mold, ensuring it’s compact and has gas escape vents if using sand. Set up your furnace in a well-ventilated area and heat the metal in the crucible, monitoring the temperature. Once the metal is molten, carefully pour it into the mold, then let it cool and solidify. After cooling, remove the casting and smooth any rough edges with a hammer or file, finishing with sanding or polishing as desired.

Safety Tips

Always wear protective gear to safeguard against burns and inhalation of fumes. Work in a well-ventilated area to avoid harmful gas exposure, and handle molten metal with caution to prevent severe burns.

Casting vs Forging

• Casting: Casting is to heat the metal to a molten state, then pour the molten metal into a pre-made mold and cool it to form the desired shape. It is suitable for making complex shapes, especially for large-sized or complex-shaped parts. Castings usually have certain pores and shrinkage holes, which may cause their mechanical properties (such as strength and toughness) to be slightly lower than forgings. It is widely used in the manufacture of engine blocks, valves, pump housings, etc.

• Forging: Forging is to heat the metal to a certain temperature and then deform it by hammering, extrusion or other mechanical forces to obtain the desired shape. Forgings are generally simple in shape, but have high dimensional accuracy and good surface quality. Due to plastic deformation, forgings have higher strength and toughness. It is widely used in the manufacture of high-strength and high-toughness parts, such as shafts, gears, connecting rods, etc.

Further reading: Stainless Steel Forging.

Stainless Steel Casting Suppliers

Choose SteelPRO Group and enjoy timely and professional technical support and after-sales service for stainless steel production.

We have a sound quality control system and all products meet the tolerance range specified by ISO standards. While ensuring quality, we provide you with cost-effective products.

Our factory production capacity has advanced casting processes and equipment and experience in large-scale production, which can meet the quantity and delivery requirements of orders in a timely manner.

Our team is constantly exploring new technologies and new processes to provide customers with better products.

If you have any needs, please contact us as soon as possible and we will help you develop the best casting solution for your industrial application.