What Properties Make a Metal Good for Engineering and Construction?

Understanding materials science is vital to creating suitable engineering solutions. The way a metal behaves under load, and over extended service periods should always be a consideration when manufacturing or implementing a component.

In order to quantify the difference between metals, we first need to understand what their measurable properties are. In this article, we’ll go through some of the key features for selecting a metal for engineering or construction projects.

Importance of Correct Material Selection

Materials come in a wide variety of section sizes, thicknesses, grades and states of temper, each with differing strength and durability properties. It’s important to select the correct material for multiple reasons, all surrounding the fine balance between quality and cost.

Safety

One of the first considerations when selecting materials is the ability to withstand the expected loads involved, also factoring in a margin of safety. This is especially important when manufacturing anything that is safety-critical.

Cost

Another important factor when engineering a system or component is cost. Some materials, like mild steel, are cheap and easy to obtain and manufacture. Others, such as Titanium or exotic alloys, are the opposite.

Longevity

Tied to both cost and safety, some materials are more resistant to wear and tear than others, be this through normal usage or corrosion. Where a component needs to last a long time in harsh conditions, corrosion resistance should be a priority in material selection.

The Importance of Durability in Metal Selection

Long-term durability is something that affects performance, cost and safety. A material that is able to withstand the impacts, strain, and wear of heavy service will provide an overall better, more cost-effective solution than one that requires replacement.

Impact and Wear Resistance

Depending on the application, high energy impacts and wear can be a normal condition for a part to withstand. Things like vehicle accessories, tools and anything that gets manipulated or moved by people or machinery will likely receive impact or wear during use.

Wear resistance is something that takes particular care to manage; the length of time a material can withstand abrasion depends on many factors, including the material itself, the substance that is causing the impact, and the conditions of operation.

Thermal and Electrical Conductivity: How These Properties Affect Performance

Thermal and electrical conductivity are closely linked; most materials that are good thermal conductors are also good electrical conductors. This is because the same atomic property affects both; the number of free electrons, allowing energy to move through the metal more easily.

Good thermal conductivity can be both a positive and negative property for a metal, depending on its usage. Parts such as heat shields and turbine blades (that get very hot) need to withstand high temperatures, and not having good conductivity is good in this instance.

However, parts such as cooking pans or heat exchangers need to be able to conduct heat well to function. In this instance, materials such as aluminum and copper are often used to assist with heat transfer.

Thermal conductivity can be a limitation, such as during manufacture. A good example is when welding aluminum, the high thermal conductivity can cause issues with heat input to the material if not properly managed.

Strength to Weight Ratio: Maximizing Efficiency

Strength is a big factor when deciding on a metal to use; some metals, like steel, are renowned for their high strength, whilst others, such as aluminum, are not. Why then is aluminium used in so many high-strength applications such as aerospace and performance vehicles?

Whilst aluminum is only half as strong as steel, it is one-third the weight of it. It is so light that its ratio of strength to weight is higher than steel. This means that whilst you’ll typically need twice as much volume of aluminum compared to steel, to withstand a certain load, the aluminum will still be lighter overall.

With even more exotic materials such as Titanium, the strength-to-weight ratio is even higher. The downside with such materials is that the material and manufacturing costs are higher than those of steel.

In some cases, the extra cost is not justified, in things such as bridges and rail products. However, when weight costs money, such as in aviation, or is the difference between a successful component and an unsuccessful one, such as in racing or sports, the extra strength-to-weight ratio is worthwhile.