As a factory specializing in stainless steel investment casting, Shandong Manek Casting Co., Ltd. has experience in producing various stainless steel investment castings. In this article, we will introduce stainless steel investment casting from multiple aspects, including the process of stainless steel investment casting, stainless steel grades, application fields of stainless steel, and its advantages.
What is Stainless Steel Investment Casting?
Stainless steel investment casting is a precision casting process that creates complex shapes of stainless steel parts by using a soluble wax model. The process involves the creation of a wax model, followed by coating it with refractory materials, then melting the wax and replacing it with stainless steel, and finally heat treatment and finishing. This method can produce castings with precise dimensions and excellent surface quality, widely used in aerospace, medical, and industrial applications.
Stainless Steel Precision Casting Process
Stainless steel investment casting is a precision casting method suitable for producing complex shapes and parts with high accuracy. Below is the main process of stainless steel investment casting:
- Model Making: Creating an accurate model of the required casting using soluble wax material, typically identical in shape to the final casting.
- Wax Treeing: Connecting the wax model to a wax gating system to facilitate the flow of metal into the model.
- Slurry Coating: Dipping the wax model in liquid gypsum slurry and then coating with refractory sand. Repeated dipping and coating forms a solid shell.
- Dewaxing: Heating the shell with the wax model, melting the wax and allowing it to flow out, leaving a cavity. At this stage, the shape inside the shell is identical to the required casting.
- Preheating and Pouring: Preheating the shell to enhance its strength and prepare for casting. Pouring the melted stainless steel into the preheated shell.
- Solidification and Shell Removal: Allowing the metal to cool and solidify inside the shell. Once solidified, the shell can be broken and removed, revealing the casting.
- Post-processing: Subsequent operations such as cutting the gate, grinding, heat treatment, etc., to meet specific dimensional and surface quality requirements.
Stainless steel is a steel material with chromium as the main alloying element, containing at least 10.5% chromium, forming a protective oxide film. This characteristic gives stainless steel excellent corrosion resistance, making it favored in many industrial and household applications. Depending on the alloy composition and microstructure, stainless steel can be divided into austenitic, ferritic, martensitic, and duplex types, each with unique mechanical properties and corrosion resistance characteristics to meet various usage requirements.
Common Stainless Steel Alloys
Grade | Classification | Features and Applications |
304 | Austenitic Stainless Steel | Good corrosion resistance, common in food processing, household applications |
304L | Austenitic Stainless Steel | Better welding properties, used in chemical, food industry, etc. |
316 | Austenitic Stainless Steel | Enhanced corrosion resistance, especially to chlorides, used in marine, chemical equipment |
316L | Austenitic Stainless Steel | Improved weldability, high corrosion resistance, used in marine, chemical industry, etc. |
430 | Ferritic Stainless Steel | Moderate corrosion resistance, cost-effective, used in interiors, kitchen utensils |
420 | Martensitic Stainless Steel | Hardenable by heat treatment, used in tools, surgical instruments |
2205 | Duplex Stainless Steel | Good corrosion resistance and strength, used in marine equipment, chemical industry |
17-4 | Martensitic Stainless Steel | Various strengths and hardness achievable by heat treatment, used in aerospace, petroleum, chemical |
Common Chemical Elements of Stainless Steel Alloys
Grade | Cr | Ni | Mo | Cu | C | Mn | Si | P | S | Fe |
304 | 18-20% | 8-10% | – | – | ≤0.08% | ≤2.0% | ≤1.0% | ≤0.045% | ≤0.03% | Balance |
304L | 18-20% | 8-12% | – | – | ≤0.03% | ≤2.0% | ≤1.0% | ≤0.045% | ≤0.03% | Balance |
316 | 16-18% | 10-14% | 2-3% | – | ≤0.08% | ≤2.0% | ≤1.0% | ≤0.045% | ≤0.03% | Balance |
316L | 16-18% | 10-14% | 2-3% | – | ≤0.03% | ≤2.0% | ≤1.0% | ≤0.045% | ≤0.03% | Balance |
430 | 16-18% | – | – | – | ≤0.12% | ≤1.0% | ≤1.0% | ≤0.040% | ≤0.03% | Balance |
420 | 12-14% | – | – | – | ≤0.15% | ≤1.0% | ≤1.0% | ≤0.040% | ≤0.03% | Balance |
2205 | 22-23% | 4.5-6.5% | 3-3.5% | – | ≤0.03% | ≤2.0% | ≤1.0% | ≤0.030% | ≤0.02% | Balance |
17-4 | 15-17.5% | 3-5% | – | 3-5% | ≤0.07% | ≤1.0% | ≤1.0% | ≤0.040% | ≤0.03% | Balance |
Differences Between 304 VS 304L, and 316 VS 316L
304 and 304L, and 316 and 316L are common stainless steel alloys. Their differences mainly reflect in chemical composition and certain performance characteristics. The differences between 304 and 304L, and 316 and 316L mainly lie in carbon content and specific environmental corrosion resistance.
The selection of appropriate materials should be determined according to specific application requirements. Below is a comparison table for 304, 304L, 316, and 316L stainless steel:
Feature | 304 Stainless Steel | 304L Stainless Steel | 316 Stainless Steel | 316L Stainless Steel |
Chemical Composition | Contains 18% chromium and 8% nickel, with small amounts of carbon, manganese, etc. | Contains 18% chromium and 8% nickel, with carbon content below 0.03% | Contains 16-18% chromium, 10-14% nickel, 2-3% molybdenum, along with small amounts of carbon, manganese, etc. | Contains 16-18% chromium, 10-14% nickel, 2-3% molybdenum, with carbon content below 0.03% |
Corrosion Resistance | Good, performs well in most corrosive environments | Similar to 304, less susceptible to intergranular corrosion during welding | Higher, excellent performance in chloride environments | Similar to 316, less susceptible to intergranular corrosion during welding |
Machinability | Good | Good | Good | Good |
High-Temperature Performance | Fair | Fair | Good | Good |
Application Areas | Food processing, chemical industry, medical devices, etc. | Welded structures, environments with high corrosion resistance requirements | Marine environments, chemical industry, etc. | Welded structures, marine environments, chemical industry, etc. |
Advantages of Stainless Steel Investment Casting
Stainless steel investment casting is a widely used process with many unique advantages. Below are some core benefits of stainless steel investment casting:
- Corrosion Resistance: Stainless steel is praised for its excellent corrosion resistance. Combined with the precision of investment casting, it ensures integrity and functionality in many extreme environments, such as chemical processing and marine engineering.
- Strength and Durability: Stainless steel has high strength and hardness, and investment casting allows these characteristics to be retained in complex geometries. This means you can create more detailed, precise parts while maintaining the robustness and durability of stainless steel.
- Hygiene and Cleanliness: Stainless steel’s antibacterial properties make it an ideal choice for food and beverage, medical, and pharmaceutical industries. The precision and smooth surface of investment casting, combined with these properties, further enhances its applicability in these applications.
- Temperature and Pressure Tolerance: Stainless steel can operate under extreme temperatures and pressures, and investment casting ensures precise dimensions and shapes even under these conditions. This makes it extremely useful in high-pressure and high-temperature environments like energy, oil, and natural gas.
- Aesthetics: Stainless steel has an elegant natural shine, and combined with the superior surface quality of investment casting, it can achieve an attractive appearance without additional polishing or treatment. This is a welcome feature in home decor, automotive, and many consumer goods.
- Cost-effectiveness: Although the cost of stainless steel material itself may be higher, its durability and low maintenance requirements make the overall ownership cost relatively lower. Combined with the production efficiency of investment casting, it offers an economical and effective solution for many applications.
- Environmental Sustainability: Stainless steel is recyclable, and combined with the precision and material efficiency of investment casting, provides a more sustainable production method.
- Customization and Flexibility: Stainless steel investment casting allows extensive customization and design flexibility to meet specific performance requirements and aesthetic goals.
In summary, stainless steel investment casting combines the various inherent advantages of stainless steel with the flexibility and precision of investment casting. Whether in terms of durability, functionality, or aesthetics, this combination offers unique advantages to designers and engineers, widely applicable to various industrial and consumer goods applications.
Stainless Steel Investment Casting Applications
The numerous advantages of stainless steel investment casting make it the preferred choice in many industrial and commercial sectors. From large structural components to small precision parts, this process enables accurate manufacturing and efficient production.
Aerospace Industry
Stainless steel investment casting plays a crucial role in the aerospace industry. The precision casting process used to manufacture turbines, engine parts, attachments, and other key components is highly favored due to its high corrosion resistance and strength requirements. Through this process, aerospace engineers can create key components with complex geometric shapes and precise dimensions.
Medical Devices
In the medical field, stainless steel investment casting is used to produce surgical instruments, prosthetics, and implants. Precise size control and excellent biocompatibility make this process an ideal choice in medical device manufacturing.
Automotive Industry
The automotive industry widely utilizes stainless steel investment casting to manufacture engine parts, chassis components, sensor seats, etc. This method helps save weight, thereby improving fuel efficiency in cars, while meeting strength and durability demands.
Energy Industry
Stainless steel investment casting also plays a key role in the energy industry, particularly in producing drilling tools, turbines, and other energy transmission and conversion components. These parts must withstand high temperatures and corrosive environments, hence strict requirements on materials and processes.
Marine Industry
In the marine industry, stainless steel investment casting is used to manufacture ship components like valves, pumps, and hydraulic systems. The seawater environment imposes strict requirements on material corrosion resistance, and this casting process meets these needs.
Chemical and Petroleum Industry: In the chemical and petroleum industry, this casting method is used to produce complex valves, pipe fittings, and pressure vessels to meet high corrosion and temperature resistance, ensuring safe and efficient chemical processing.
Food and Beverage Industry
The food and beverage industry uses stainless steel investment casting to manufacture components in contact with food, such as pumps, valves, and filters. This process meets the strict requirements of the food industry for cleanliness and hygiene.
Tools and Hardware Products
Stainless steel investment casting is also used to produce complex tools and hardware accessories like wrenches, screwdrivers, and gardening tools to meet high strength and wear resistance requirements.
Art and Decorations
Moreover, this process is widely used in the manufacture of art and decorations, such as sculptures and jewelry. High surface quality and fine detail representation make stainless steel investment casting an ideal choice for artists and designers.
Stainless Steel Investment Casting Surface Treatment Methods
Surface treatment not only enhances the mechanical and chemical properties of the castings but also improves their appearance and feel. Through appropriate surface treatments, stainless steel investment casting components can meet various complex and strict application requirements. Below are some commonly used surface treatment methods:
- Polishing and Grinding: By mechanical or manual grinding to remove surface defects and enhance appearance. This treatment is widely used for applications requiring smooth and glossy surfaces.
- Pickling and Passivation: By soaking in acidic solutions to remove surface oxidation and stains. Passivation increases stainless steel’s corrosion resistance by forming a corrosion-resistant surface oxide film.
- Shot Blasting and Sandblasting: By high-speed projectile of small particles to clear surface oxidation, sprues, and other defects. This method enhances surface fatigue strength and adhesion.
- Electroplating and Chemical Plating: By electrochemical or chemical reactions to deposit metals or other materials on the casting surface. This treatment is commonly used to enhance wear resistance, corrosion resistance, or change appearance.
- Heat Treatment: By heating and cooling to alter the casting’s microstructure, thus improving strength, hardness, toughness, and corrosion resistance.
- Painting and Coatings: By painting or coating special materials to improve appearance, corrosion resistance, and wear resistance. These coatings can be paints, plastics, rubber, or special ceramic and metal coatings.
- Anodizing: By anodizing to form an oxide film on the casting surface, increasing wear and corrosion resistance. Although commonly used with aluminum alloys, special applications can be found on stainless steel castings.
As an investment casting manufacturer, we can offer various surface treatment methods for stainless steel investment casting. If you have any surface treatment requirements, please feel free to contact our technicians.
Stainless Steel Investment Casting Company and Foundry
Shandong Manek Casting Co., Ltd., one of China’s largest stainless steel investment casting enterprises and mechanical manufacturing companies. We can produce customized stainless steel castings ranging from 5 g to 100 kg and provide CNC machining service as well as surface treatment for stainless steel castings. If you have any stainless steel casting needs, please contact our technicians.
