UNDERSTANDING METAL PROPERTIES
Metals are all around us, in the things we use to cook, drive, work, and live. When choosing a metal for a cast product or other specific application, it’s important to make sure that its properties will be suitable for the expected operating conditions.
There’s a big difference between the kind of metal used in a skyscraper and the kind of metal used in a gate valve. Some metals are pure elements, like iron (Fe) and aluminum (Al), but most products are made from alloys, or mixtures of metals. Manufacturers must consider many variables before deciding which alloy to use for a particular product.
Factors that go into choosing the right metal alloy include:
- Performance, as well as the interrelations between these four factors.
Mechanical Properties, Physical Properties and Chemical Properties
In large part, the ways of distinguishing metals can be broken down into three categories: mechanical properties, physical properties and chemical properties.
Physical properties refer to observable characteristics of a material. Examples of physical properties include color, melting point and density. Mechanical Properties describe how a material reacts to external forces like pushing, pulling or twisting. Strength, hardness and elasticity are examples of mechanical properties.
Chemical properties explain how a material interacts with other materials in a given environment. These properties determine how the material will behave on a molecular level. Chemical properties are the basis for physical and mechanical properties.
Neither physical nor mechanical properties are constant; they change according to the environment. For example, elasticity (mechanical property) and density (physical property) are dependent on material temperature.
Common metal properties
Metals also have a number of shared properties, which help to define them as metals and separate them from non-metal materials. Metal elements like iron, aluminum, copper, magnesium, lead, tin, and zinc, as well as alloys like steel, brass, and bronze, display the properties of:
- Luster: when free of surface contaminants, metals are shiny.
- High thermal conductivity: compared to non-metals, metals are good conductors of heat.
- High electrical conductivity: metals are also good conductors of electricity.
- Ductility: more than most non-metal materials, metals can be bent, stretched and otherwise deformed without easily breaking.
- Magnetism: not all metals are magnetic, but many alloys containing iron, nickel or cobalt will exhibit degrees of magnetic behavior.
Physical and mechanical properties both determine how a metal will behave in the real world. For manufacturers, understanding these properties is an important step in choosing the right materials for their products.
Casting professionals must have a thorough understanding of metal properties in both solid and liquid phases. At the Eagle Group, we have trained metallurgists who work with customers to determine the optimal material chemistry, processing and treatments for each product.
To learn more about the Alloys we use for casting and machining, check out this blog post.
Written by Jason Bergman
Jason Bergman is Senior Quality Engineer and Metallurgist at Eagle Alloy. He has been with the company since 2013.