What are the Mechanical Properties of Metals?
Table of Contents
- Mechanical Properties of Metals
- Strength
- Ductility and Malleability
- Toughness
- Fatigue Resistance
- Hardness
Introduction
In the metal manufacturing and production industry, mechanical properties play a crucial role in selecting the appropriate alloy for any specific task. Throughout casting, machining processes, and determining the service life of metals, the chosen material will be subjected to various external forces. Manufacturers must produce materials that meet customer requirements at every stage. By understanding mechanical properties, industrial experts and manufacturers can make informed choices about materials and processes.
Primary Mechanical Properties of Metals
The way a material reacts to loads or forces is described by its mechanical properties. These properties are not constant and may vary depending on temperature and other external factors. Therefore, metal producers must fully understand the working environment and function of a part before recommending a material. Key mechanical properties of metals include:
- Strength
- Ductility and Malleability
- Toughness
- Fatigue Resistance
- Hardness
Strength
Strength can be measured in various ways but generally represents the amount of force an object can withstand without bending or breaking. The strength-to-weight ratio is a key characteristic of metals, informing manufacturers how much material is needed to meet a specific strength requirement.
Strength is often measured based on how a material responds to stress or forces applied in three configurations: compression, tension, and shear. In compression, forces are directed toward the central point of the material. In tension, forces act in opposite directions, pulling the material apart. Shear forces, on the other hand, act parallel to each other in opposing directions.
Ductility and Malleability
While strength is a good predictor of how metals will perform in real-world applications, manufacturers often need to push metals beyond their limits to create new shapes. Ductility and malleability describe how easily a metal can be manipulated without breaking.
The ductility of metals is widely used in bending processes, such as metal forming or press brakes. This property allows metals to be shaped into the desired form using bending equipment like press brakes.
To learn more about press brakes and how they perform bending operations, click here.
Ductility refers to a metal’s ability to stretch, roll, or extrude without breaking. Malleability, on the other hand, relates to compressive stress, such as flattening. Aluminum’s high malleability makes it a popular choice for manufacturing thin foil sheets.
Since a material’s behavior changes with temperature, a metal may exhibit good ductility or malleability at high temperatures but weaken at room temperature. Centuries ago, blacksmiths understood this variability and heated iron products to make them glow red before starting the forging and shaping process.
Toughness
In materials science and metallurgy, toughness is defined as the ability of a material to absorb energy and undergo plastic deformation before fracturing. Toughness reflects an ideal balance between strength and ductility. The toughest metals are those capable of absorbing the most energy before breaking.
Fatigue Resistance
In real-world applications, metal parts are often subjected to repetitive stresses over extended periods. While no single instance of stress may challenge a part’s strength, ductility, or toughness, repeated stress cycles can lead to material failure. According to the American Society of Metals, approximately 90% of mechanical failures are caused by fatigue due to repetitive stress over time.
Fatigue resistance refers to a part’s ability to endure repeated and cyclical stress without breaking or undergoing permanent deformation. As with other mechanical properties, the fatigue resistance of an alloy depends on the temperature at which stress is applied and other environmental factors.
The fatigue resistance of a component is influenced not only by its material composition but also by any defects or flaws present. Issues such as porosity, cracking, or other manufacturing defects can significantly reduce a part’s fatigue resistance.
Hardness
Hardness in materials can be categorized into components such as resistance to deformation, resistance to abrasion, or resistance to cutting. Metals exhibit a strong correlation between tensile strength and hardness, and it is often possible to increase the hardness of steel by raising its carbon content.
Conclusion
This article has explored the key mechanical properties of metals, including strength, ductility and malleability, toughness, fatigue resistance, and hardness. By understanding and considering these properties, metal and material manufacturers must produce products that meet the expectations and needs of their customers.