Visually identifying different types of steel and other metals isn’t necessarily that hard to do. Once you have read this article, you should be able to distinguish between common metals, understand basic metalworking processes and recognise different shop materials (such as tubing, flanges, elbows and channels) as well as  structural members (like I-beams, trusses and girders).

 

This article only covers the basics of visually identifying different types of steel and other metals. With more experience it is also possible to identify unmarked metals using a spark test or magnet. Another useful way to identify steel and other metals is through a stock classification number system that is typically labelled on supply bins.

 

Below are visual ways of identifying some of the most common types of steel and other metals. However, if you need expert assistance, we recommend contacting your local steel supplier to discuss your steel needs.

 

Carbon Steel

 

Carbon steel is an affordable metal used in a variety of commercial industries ranging from mining to construction. Some example of it’s use include the building of bridges, infrastructure, buildings and pipelines. There are varying grades of carbon steel. The higher the carbon content, then the harder and more brittle the steel. If more ductility is needed them then lower amounts of carbon are required. Lower carbon steel is primarily used in the production of structural steel products. Higher carbon steel is used to produce cutting tools.

 

Unlike lower carbon, which can be welded easily, higher carbon content steel is very sensitive to heat. It will often require treatment before or after the heating process to avoid damage to the structure of the steel.

 

Steel rusts very easily and is often needed to coated or painted in order to protect it. Freshly ground carbon steel is shiny and metallic, but most carbon steel has dark dull tone to it. Steel produces many sparks when put under a grinder.

 

There are four main types of carbon steel. They are hard to discern visually, but you can typically tell which type is used depending on the object. Some examples are listed below:

 

Type Objects Carbon Content

Mild Steel Pipes, steel framing 0.05% – 0.3%

Medium Carbon Forged parts, Vehicles 0.3% – 0.6%

High Carbon Springs, Wires 0.6% – 1%

Tool Steel Cutting tools, Drills 1% – 2%

 

The iron content can also affect the type of steel it is. When the iron content exceeds 2%, then the metal is considered cast iron steel. This type of steel is very rigid and hard to handle, weld or manipulate.

 

Stainless Steel

 

Stainless steel is essentially carbon steel, but with 10%+ chromium added to the chemical makeup of the steel. The addition of chromium helps prevent the steel from rusting. This type of steel can be found in laboratories and kitchen around the world, as it is excellent for sealing liquids and chemicals. The texture of stainless steel is grainy and will have a silver sheen to it. There are other alloys present within stainless steel – these may include nickel or even molybdenum.

 

There are five main types of stainless steel. It is not possible to tell the difference between them, however it is possible to tell austenitic, unlike other types of steel, is not magnetic. Below are the three types of stainless steel:

 

Austenitic

 

This is the most common type of stainless steel and is composed of 18% chromium and 8% nickel. It is prized for it’s resistance to corrosion and can commonly be found to be used to contain chemicals and for structural applications.

 

Ferritic

 

This type of stainless only contains chromium alloy and is used typically for cooking utensils and for the trim on vehicles.

 

Martensitic

 

This magnetic type of stainless steel is used on pump shafts, turbines and fasteners.

 

Precipitation Hardening

 

This type of steel is prepared through a special heat treatment that is made to prepare valves and gears for petrochemical equipment.

 

Duplex

 

This type of steel combines three different alloys together: nickel, molybdenum and chromium. This type of steel is primarily used for pipelines.

 

Aluminum

 

Aluminium is extracted from an ore known as ‘bauxite’ and then processed through a extended process of electrolysis. Aluminium is a specialty type of metal that has become highly popular in the past century. You can find aluminium in everything from cars to electronics. It is not ferrous and is instantly recognisable for it’s lack of rust and incredible shine (unless matted of course!). Aluminium produces no sparks when placed on a grinder.

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