Choosing materials is never a trivial matter. It determines the core performance of parts, including strength, toughness, hardness, corrosion resistance, high-temperature resistance, and the crucial final cost.
If the wrong material is chosen, even the most perfect design and manufacturing process may cause the part to fail prematurely in practical use, leading to greater losses.
In this article, we will focus on introducing several major types of casting alloys that have been widely tested. We will also analyze their characteristics and application scenarios. At the same time, we will share how QD ensures that the material you choose can be perfectly transformed into high-quality products that meet expectations.
Core Considerations for Material Selection
When you evaluate a material, be sure to consider it from the following core dimensions:
Mechanical Properties
- Strength: The ability of a material to resist deformation and fracture. It is usually measured by tensile strength and yield strength. For load-bearing structural parts, this is the primary indicator.
- Toughness: The ability of a material to absorb energy and undergo plastic deformation before fracturing. Opposite to brittleness, it is crucial for parts that bear impact or vibration.
- Hardness: The ability of a material to resist local plastic deformation. It is usually related to wear resistance.
Physical and Chemical Properties
- Corrosion Resistance: The ability of a material to resist erosion from the environment (such as air, water, acids, alkalis, salts, etc.).
- High-Temperature Resistance: The ability of a material to maintain its mechanical properties and chemical stability at high temperatures. It is extremely critical for applications like engine components and turbine disks.
- Thermal/Electrical Conductivity: For specific functional parts such as heat sinks and electrical components, this is an important basis for material selection.
Processability and Economy
- Casting Performance: It includes fluidity, shrinkage rate, hot cracking tendency, etc. It affects the success of the investment casting process and the yield rate. The process experts at QD have rich experience in this aspect.
- Machinability: Whether the castings are easy to conduct subsequent cutting processing.
- Cost: It not only includes the cost of the material itself, but also should comprehensively consider the full-life-cycle costs such as casting difficulty, yield rate, and post-processing cost.
The ideal material selection is to find the optimal cost solution while meeting the minimum requirements for the part’s service conditions. There is no “best” material, only the “most suitable” material.
Material Series 1: Stainless Steel – A Model of Corrosion Resistance and Versatility
Stainless steel is one of the most widely used materials in investment casting. Its main properties come from the passive film formed by the Cr element. We will focus on introducing several common grades:
| Grade | Main Characteristics | Typical Application Scenarios | Remarks |
| 304/304L | Excellent corrosion resistance. Good formability and weldability. | Food processing equipment, architectural decoration, medical devices | The most widely used austenitic stainless steel. Not suitable for chloride ion environments |
| 316/316L | The resistance to pitting and crevice corrosion is better than 304. Suitable for chlorine containing environments. | Marine environment equipment, pharmaceutical equipment, chemical pipelines | Known as “ship steel”. It is a more reliable corrosion resistant choice. |
| Duplex steel 2205 | The yield strength is twice that of 304 and 316. It has extremely high stress corrosion cracking resistance and excellent pitting corrosion resistance. | Oil and natural gas pipelines, pressure vessels, desalination equipment | High strength. Can reduce wall thickness. More economical in some cases. |
QD provides standard stainless steel grades. We can also offer material upgrade or customization suggestions based on your specific corrosion environment. This ensures that your castings can serve for a long time in harsh environments.
Material Series 2: Low-Alloy Steel and Carbon Steel – The Cornerstone of High-Strength Structural Parts
When the core requirements for parts are high strength, high hardness and excellent wear resistance, while the requirement for corrosion resistance is not high, low-alloy steel and carbon steel are cost-effective choices.
Carbon Steel: Its main alloying elements are iron and carbon. Its strength increases as the carbon content rises. But its plasticity and weldability will decrease. It is suitable for structural parts that do not have extreme strength requirements and work in dry environments.
Low-Alloy Steel: Low-alloy steel is made by adding small amounts of elements such as Cr, Ni, and Mo to carbon steel. Through heat treatment, its strength, toughness, and hardenability can be significantly improved. A common casting grade, such as ZG40Cr1, is widely used in:
- Automotive industry: Key safety parts like connecting rods, gears, and steering knuckles.
- Construction machinery: Excavator bucket teeth, track shoes, and hydraulic components.
- Construction accessories: High-strength connectors and anchorage devices.
QD’s advantage lies in our precise control over the heat treatment process of these steels. We can customize heat treatment plans according to your performance indicators. This ensures that every batch of castings achieves stable and uniform mechanical properties.
Material Series 3: Superalloys and Cobalt-Based Alloys – Conquering Extreme Environments
For parts that work in environments with extremely high temperatures (usually over 600°C), high stress, strong oxidation, and severe corrosion, ordinary stainless steel and alloy steel are no longer effective. At this point, we need to use the “ace” in the material field – superalloys.
Such alloys usually take Ni or Co as the matrix, and add a large amount of elements such as Cr, Mo, W, Al, and Ti to achieve the following properties:
- Excellent high-temperature strength: It can still maintain high strength at temperatures close to its melting point.
- Outstanding creep resistance: The ability to resist slow deformation under high temperature and continuous stress.
- Excellent oxidation resistance and corrosion resistance.
| Type | Core Characteristics | Typical Applications |
| Nickel – based superalloy | It has the best comprehensive performance and is the most widely used superalloy. It achieves extremely high high temperature strength through solid solution strengthening and precipitation strengthening. | Turbine blades, guides, casings of aerospace engines; gas turbine blades; nuclear reactor components |
| Cobalt – based superalloy | It has extremely excellent thermal fatigue resistance and wear resistance. It can maintain hardness at higher temperatures. | Engine nozzles; high-temperature molds; wear-resistant valves; artificial joints |
Investment casting is the only feasible process for manufacturing superalloy parts such as complex hollow air-cooled turbine blades. QD has been deeply engaged in this field for many years and owns mature technologies in mold design, shell making, smelting and heat treatment. We provide one-stop solutions from material selection to finished product delivery.
Material Series 4: Aluminum Alloys and Copper Alloys – Representatives of Lightweight and Excellent Functionality
Aluminum Alloys: The biggest features of aluminum alloys are low density and high specific strength. Besides, they also have good thermal conductivity, electrical conductivity and atmospheric corrosion resistance.
- Applications: They are widely used in aerospace, automobiles, electronic communication casings, heat sinks, etc.
- Casting Grades: Such as ZL101A, ZL104, etc. Through investment casting, thin-walled and complex lightweight aluminum parts can be produced. This is hard to achieve with other processes.
Copper Alloys: The most prominent advantage of copper alloys is their excellent thermal conductivity and electrical conductivity. They also have good wear resistance and corrosion resistance.
Main Types:
- Brass: It has good mechanical properties and low cost. It is used for valves, pipe fittings and decorative parts.
- Tin Bronze: It has excellent wear resistance and corrosion resistance. It is often used to make worm gears, bearings and marine accessories.
- Aluminum Bronze: It has high strength, good wear resistance and corrosion resistance. Especially, it can resist seawater erosion. It is used for load-bearing components of heavy machinery.
The choice of non-ferrous metals is usually based on specific functional needs for weight, thermal conductivity or electrical conductivity. QD can accurately control the chemical composition of these alloys to ensure the stability of their physical properties.
QD: Expert Support – A Solid Backing for Quality
Choosing materials is just the first step. How to ensure the composition of the smelted metal liquid fully meets the standards? How to verify that the material of the final casting is qualified? Behind this is the support of a strong quality control system.
At QD Casting Factory, we have invested in advanced direct-reading spectral analyzers for rapid composition analysis before casting. Every batch of molten steel/alloy liquid must be inspected by the spectrometer before pouring. This not only avoids batch waste caused by composition deviations, but also fulfills our commitment to customers.
In addition, we can provide authoritative third-party material inspection reports or standard-compliant material certification certificates at the customer’s request. This provides complete evidence for the quality traceability of your products.
Contact Us
Are you hesitant between several materials? Are you not sure how to balance performance and budget?
Please leave your challenges to us. QD’s team of metallurgical and process engineers is ready to provide support for you at any time.
Tell us about your part information:
- Working Environment: Temperature, contact medium (water, gas, acid, alkali, etc.), and stress conditions.
- Performance Requirements: Key mechanical property indicators (strength, hardness, etc.), and special requirements (wear resistance, thermal conductivity, non-magnetism, etc.).
- Budget and Batch: The cost expectation and production scale of the project.
Based on this information, we will recommend the material and process plan with the best cost-performance ratio for you, helping your investment casting project get off to a winning start.
FAQ
1. Can I provide my own material standards (such as ASTM, DIN, JIS) for casting?
Of course you can. QD is familiar with various international and industry standards. You only need to provide the standard number and specific grade. We will convert them into internal process and composition specifications.
2. Superalloys are very costly. Are there any alternative options?
It depends on the working temperature. If the temperature is not extremely high (such as below 650°C), some high-performance stainless steels (such as 310S) or iron-nickel based alloys may be more cost-effective alternatives. Our experts can conduct substitution evaluations for you.
3. Can you guarantee that the mechanical properties of the castings meet the standard requirements?
Yes. We guarantee this through three strict controls: composition control, heat treatment process control, and performance inspection (with mechanical property testing of cast test bars). The performance reports we provide are credible.
4. Can aluminum alloy castings undergo surface treatments like anodizing?
Yes. Aluminum castings produced by investment casting have high density and good surface quality. They are very suitable for subsequent surface treatments such as anodizing, electroplating, and painting. When selecting materials, we will consider your subsequent surface treatment needs and recommend suitable aluminum grades.
5. Do you accept small batch and multi variety orders?
The process characteristics of investment casting are very suitable for small batch and high complexity orders. QD has the ability of fast and flexible mold making and production response. Whether it is sample parts in the R&D stage or small and medium batch production, we are willing to serve you.