A major advantage to investment castings involves the types of metals used to produce parts. Any metal that can be melted can be cast using this process. Investment casting metals come in two categories: nonferrous and ferrous metals. Selecting which metals within these two groups will be based on your application. When determining the differences between metals, the major factor depends on if there is iron present.
Ferrous metals contain iron while non-ferrous metals do not. Due to this iron, metals possess greater levels of conductivity. The metal also possesses a good tensile strength that allows it to experience high levels of stress without breaking. Possessing this great mechanical property along with strength and durability allows customers to use ferrous metals for parts in electrical and high-stress applications.
The one thing to keep in mind is that due to possessing iron, many ferrous metals are prone to corrosion. Applications where there will be an abundance of moisture, humidity, solvents, motor oils, and other caustic substances may wear out the part until it fails. To work around this problem, ferrous metals may have additives such as chromium placed into the melt to provide better corrosion resistance. By enhancing these alloys, the manufacturer may develop investment castings that can be used in such harsh environments.
Types of ferrous metals include steel, cast iron, stainless steel, and carbon steel. Typically, ferrous metals are less expensive than non-ferrous metals as they are often used in a variety of applications including aerospace components.
For non-ferrous metals, the absence of iron makes many of the metals in this group less prone to possible corrosion and rust. These metals are very malleable, light weight and have a low tensile strength. They may also be magnetic or non-magnetic, providing additional options based on the applications.