Casting alloys are an integral part of the overall castings, which determines the casting’s mechanical and physical properties. It has an incomparable impact on different casting processes and target applications. However, we are already familiar with various metal casting processes. We mentioned in those guides that choosing suitable casting alloys is crucial. Therefore, we made this article to decide it on the table.
It is crucial that choosing the perfect casting alloys suit the definite metal casting process – as well as the target applications of that specific casting. This article describes those essential factors you should consider before choosing the appropriate casting alloys. In addition, at the end of this article, we will also discuss some of the most popular cast alloys used in most foundries.
What is an alloy?
Casting alloys combine metals with other materials that change the final product’s mechanical and physical properties. The purpose of the cast metal alloys is to make them more robust and lighter and prepare them for the required application. The substances used to combine with the primary metal are called alloying agents. The most common example of casting alloys is stainless steel. Furthermore, steels differ based on various added substances with the base metal. The benefit of using cast alloys is in the following.
- Casting alloys are usually robust and more stable than any other pure metal. This property makes them suitable for any high-strength applications.
- The alloying process improves the corrosion resistance properties of the final product. An alloy such as stainless steel casting has a high corrosion resistance level that prevents corroding. This property of the alloy makes them suitable for different applications where corrosion is a threat.
- Cast alloys have high-temperature resistivity, which makes them suitable for high-heat applications.
- Some cast metal alloys are magnetic, making them suitable for applications requiring magnets, such as generators
How to choose the best alloy for metal casting?
Choosing the suitable cast alloys for your application is not difficult if you know the fundamental factors that alter that alloy’s physical and mechanical properties. Therefore, it is crucial to discuss these factors when choosing the ideal casting alloys for your final application. Besides, most foundries also confirm these factors before the final production. In addition, foundries should provide the customer with documents for factors such as tensile strength, corrosion resistance, wear resistance, weight, temperature, etc.
The most crucial standard used to evaluate many structural materials is tensile strength. Tensile strength refers to the alloy’s capacity to withstand a certain amount of force without snapping. Typically, casting alloys are more robust than pure metals. It is important to note that alloying process reduces the electricity and thermal conductivity. Therefore, cast alloys are famous for most engineering constructions.
While choosing casting alloys, you should know the highest load of the projected system. Later, you can determine the tensile strength band that would be perfect based on the factors in the following.
Is weight a consideration in your project? It would be best if you considered switching existing casting alloys to magnesium, titanium, or aluminium. These casting alloys are incredibly lightweight and can withstand high force. As a result, you can deduct some of the unnecessary bulk weight from the system. Besides you can also choose heavy casting alloys such as steel, nickel, or aluminium accordingly.
On the other hand, stainless steel casting, carbon steel casting, and alloy steel casting could be suitable for heavy machinery. Therefore, cast alloys’ weight must play a significant role in the overall structure of a machine. So, before choosing the cast metal alloys for the final application, it is necessary to go through weight determination.
Cost analysis consists of two sub-factors impacting the overall product cost: alloy cost and process cost. Alloy costs differ according to the market condition. On the other hand, process cost refers to the cost required for the respective metal casting process. Both of these cost factors influence the overall product price.
In addition to the process cost, it is essential to note that the type of metal casting process depends on the complexity of the design and the kind of cast alloy used. The different metal casting processes offer different prices, resulting in cost variations.
The casting alloys might go through extreme heat and moisture based on your target application. Corrosion is a threat in any manufacturing process. Even in typical machines, corrosion is the most critical threat to consider. Therefore, you should know the respective alloy’s corrosion resistance properties before choosing ideal casting alloys.
The difference in corrosion resistance may vary in most alloys, particularly in aluminium and magnesium. It is important to note that you can improve the corrosion resistance property as required with a cost-effective surface treatment process.
Wear is usually a surface failure from a dynamic contact between two surfaces. It is one of the most common causes of component failure in machinery. When corrosion occurs, the specific component surface particle work against the mating surface, resulting in serious galling and seizing. Finally, it causes the machine to stop moving or freeze up.
High-performance casting alloys (HP cast metal alloys) offer high wear resistance properties. As a result, these casting alloys ensure the machines’ stability and durability. Besides, highly resistant cast metal alloys require less maintenance. Therefore, it is essential to consider the wear resistance property of casting alloys.
Another vital factor to consider when you attend to find the best cast metal alloy for your project is the heat resistivity property. Heat-resistive casting alloys are helpful for many applications where high temperature is regular. However, heat-resistive cast alloys that work above 1200 degrees Celcius are usually based on iron, nickel, or cobalt elements.
Therefore, your cast alloy may be exposed to high heat depending on your applications. Consequently, choosing the best cast alloy that can endure such temperatures and resist rust and wear.
It is the last but not least factor that you should consider while attempting to choose the ideal cast alloy for the application you require. Some casting alloys are unsuitable for welding, which means you can not weld any other components on the surface of these alloys. On the other hand, some alloys are ideal for welding. In this situation, you should be clever enough to get the best for your required application.
Types of Alloys in metal casting
As mentioned, casting alloys combine a pure base metal and other elements that alter the composition and mechanical properties. Depending on various combinations, the type of alloy varies, and this number of variations is nearly endless. However, in the following, we will discuss some of the most common casting alloys and their respective applications.
1. Stainless steel casting
Stainless steel casting is an alloy of iron as the base metal and carbon as an alloying agent. Besides, various types of stainless steel casting contain different carbon content amounts, which can not exceed 1.7%. Other than carbon content, another element, such as chromium, may also be present in some types of stainless steel casting. These types of stainless steel castings are usually shiny and corrosion-resistant.
Stainless steel casting is ideal for different applications where corrosion creates issues. However, stainless steel casting is widely popular in the food, beverage, chemical, and medical industries. Kitchen appliances, cookware, cutlery, and various machine components are famous examples of stainless steel casting applications.
2. Aluminium alloys
Aluminium alloys are not as robust as stainless steel casting but lightweight with improved durability. Although adding other elements such as iron, copper, or zinc increases the strength and durability. On the other hand, the alloying process makes aluminium alloys ductile, non-toxic, reflective, non-magnetic, and non-combustible.
Aluminium casting alloys are widely popular in electric module packaging, electronics, automotive body parts, and the wind and solar industries. In the aerospace industry, lightweight and robust elements are necessary. Aluminium alloys are ideal for such applications.
3. Nickel Alloys
Nickel is also one of the most versatile metals in the periodic table. These casting alloys usually combine nickel, iron, copper, molybdenum, or chromium. Monel, Nichrome, and Incolen are the three most common nickel alloys we might find. Monel is a combination of 70% nickel and 30% copper. In addition, Nichrome is a combination of 80% nickel and 20% chromium. Finally, Incolen combines 80% nickel, 14% chromium, and 6% iron.
These alloys are highly corrosion resistive, which makes them ideal for various applications. It can work perfectly under mineral acids, organic acids, and alkaline. Besides, nickel alloys have excellent mechanical strength, flexibility, and wear resistance. The marine piping system, hydraulic valves, and shafts are the most famous example of nickel alloy components.
4. Bronze Alloys
Bronze alloys contain bronze as the base material and copper and other additives as alloying agents. Other additives might include tin, silicon, manganese, aluminium, phosphorus, etc. However, these casting alloys are extremely strong and highly corrosion resistive. As a result, bronze alloys can be seen in ships and other nautical applications. Besides, bronze alloys are also popular in making medals, sculptures, and musical instruments.
Casting alloys combine metals with other materials that change the final product’s mechanical properties. These alloys are found in various applications in manufacturing industries. However, different applications require specific properties of the alloy. You already know the above factors, but if you still get confused about choosing the ideal alloy, don’t worry! Contact us immediately. Our expert engineers are waiting to provide you with the best solution.