Alloys in Action: Choosing the Right Metal Blend for Tough Jobs

The process of alloying can transform a relatively low-strength material into a high-performance alloy with much better physical and chemical properties than the base material.

However, selecting an alloy can be difficult, as there are many different types and grades available, each with its own strengths and weaknesses. In this article, we’ll explain some key properties to be aware of and the deciding factors in alloy selection.

What Are Metal Alloys?

An alloy is a mixture of two or more elements, where at least one is a metal. They are created with the intention of improving the chemical or physical properties of a material from those of the base or main constituent material.

The elements used to make metal alloys can be metals or non-metals; common alloying elements include carbon, nickel, chromium, manganese, silicon, cobalt, and many more.

Types of Alloys Used in Fabrication and Manufacturing

There are thousands of different alloys; they are generally grouped by the base metal:

Steel Alloys

All types of steel are alloys, being that steel is iron with a small amount of carbon; however, additional elements are added to create specific improvements in various physical and chemical properties.

There are many different steel alloys, from low carbon mild steel to high-performance structural alloys, and various other uses:

• Low carbon steel for general use: ASTM A36
• High Strength steel: ASTM A514
• Abrasion resistant wear plate: AR500
• Tool steels for machining, such as M2

A good example of how powerful the act of alloying is: ASTM A514 and A36 both comprise at least 95% iron, but the former is nearly 3x stronger in terms of tensile strength. In the case of tool and knife steels, the higher level of carbon allows them to be heat treated to tightly control hardness, something not possible with low carbon steels.

Aluminum Alloys

Aluminum is almost always used as an alloy, as it is very soft in its pure form. Aluminum is often alloyed with elements such as copper, magnesium, and zinc. Alloying elements are added to aluminum to improve everything from strength to corrosion resistance.

Some common aluminum alloys include:

• 6061 is probably the most commonly used commercial grade, having good strength, workability, and corrosion resistance
• 7000 series aluminum grades, such as 7075, are used for their extremely high strength
• 5052 grade is often considered to be a “marine grade” as it is less susceptible to degradation from saltwater than other grades
• 1000 series aluminum is often considered the economy grade, where cost is the most important factor

Stainless Steels

Stainless steel is yet another material that is an alloy by definition; it is composed of iron, carbon, and at least 11% chromium. In reality, most stainless steel grades also contain nickel, molybdenum and more.

• 300 series is one of the most common groups of stainless steel alloys, with 316 and 304 being the go-to for general fabrication of all things corrosion resistant
• 400 series is often considered a cheaper alternative, and it is less corrosion resistant but in many cases harder wearing than 304 or 316
• 2200 series stainless steels are considered “duplex” grades, as they contain both austenitic and ferritic phases

Key Properties That Make Alloys Work

Some of the key reasons for alloying a metal include:

• Increasing its tensile strength: Minor changes in a material’s metallurgy can increase both its tensile and yield strength dramatically
• Improving its corrosion resistance: Stainless steel is the best example of this, as it is essentially carbon steel with chromium added, achieving excellent corrosion resistance, depending on other alloying elements present
• Making it heat-treatable: Various aluminum and steel alloys can be heat treated to improve properties such as hardness and ductility by modifying their chemical composition
• Making it easier to manufacture with: There are grades of most metal types that have elements added to make them easier to machine, bend or weld

Alloys in Action: Industrial Applications

Almost any metal used in industry will be an alloy, except for certain precious metals. Some notable examples include:

High tensile strength steel

For demanding structures, such as skyscrapers, bridges and other large infrastructure projects, a material such as S690 or similar high tensile steels is essential.

This is because a lesser grade may not have an adequate strength-to-weight ratio for the design in question.

Aeroplane components

Alloys such as aluminum 2024-T3 have incredible fatigue resistance and a high strength-to-weight ratio; these are often used for high strength components in air and spacecraft.

Wear plate

In applications with high abrasion, such as inside materials handling or crushing equipment in quarrying or mining, high wear resistance is essential.

The additional alloying elements in grades such as AR 500, etc., mean the parts can last much longer before needing replacement.

How to Choose the Right Alloy for Tough Jobs

With all these grades and alloys to choose from, it can be difficult to pick which one to use for your application.

Cost

In most projects, the foremost determining factor in material selection is cost. Remember to consider not only the cost of the material itself, but the cost of manufacturing it into an end product.

For instance, with many high-performance alloys, pre and post heat treatment is essential with welding and certain forming processes. Other alloys, such as wear plate, can require more expensive tooling to work.

Availability

The more commonly used a material is, the cheaper it is likely to be, and the easier it will be to obtain promptly. It even serves to check with suppliers directly rather than relying on stock lists.

A particular size and type of material might offer the perfect solution to a part, but if it has a very long lead time, it can be the difference between a successful and unsuccessful project.

Strength

The tensile strength of engineering materials is typically well-documented, especially those commonly used in structural or load-bearing applications.

Manual calculations, software finite element analysis, and even rules of thumb can be used to determine if a material is strong enough. Always consult a structural engineer before manufacturing, testing or implementing load-bearing designs.

Consider Metals Supermarket

Stocking everything from mild steel to tool steel, stainless steel to aluminum and everything in between, Metals Supermarket can supply the alloys you need.

As well as having great prices, nationwide delivery of cut-to-length materials is easily ordered online and in-store. Start your search for the perfect material here.