Black Steel and Galvanised Steel

How do black steel and galvanised steel differ? Which suits knock-down houses and office units?

Black steel and galvanised steel may look similar from the outside, but their properties and uses differ more than you might think.

For anyone choosing a knock-down house, knock-down unit, office unit, container office unit or prefabricated building, the structure is one of the important factors not to overlook, because the material chosen affects not only strength but also rust protection, service life, maintenance and long-term cost.

Many people may have heard the terms "black steel" and "galvanised steel" but are not sure how they differ, or wonder:

"If both types of steel can be used for the structure, why choose galvanised steel?"

Especially for prefabricated buildings installed and used in Thailand, with its heat, humidity, rain and varied environments, the choice of structural material should not be based only on the price per square metre or the price of the building, but should also take into account the environment and long-term use.

What is black steel?

Black steel is steel with a black surface, also called structural steel or black structural steel, and sometimes box steel. It is produced by casting or by rolling steel into shape. As for price, black steel is lower-priced than galvanised steel, because black steel does not need the hot-dipping and anti-rust coating steps, which are costly, and it is also easy to find. This has made black steel an important structural material, which is why there are many TIS (มอก.) standards for it to protect consumers.

The properties of black steel are durability and good resistance to wind pressure and friction.

Advantages and limitations of black steel

Understanding the advantages and limitations of black steel will help you decide better whether or not to use it in various jobs. So let's go into the details of the pros and cons of this type of steel.

Advantages : Lightweight, smooth seams, durable and long-lasting, withstands high pressure well, carries heavy loads, lower-priced than galvanised steel, easy to find, widely used in construction

Disadvantages: Rusts easily if not painted with an anti-rust primer

What is galvanised steel?

Galvanised steel is steel that has been coated or plated with zinc to prevent rust. This additional material and production step means galvanised steel is usually more expensive than black steel. However, the properties, advantages and limitations of galvanised steel also differ from those of black steel.

Properties

Note that the production process of galvanised steel differs from that of black steel, giving galvanised steel some interesting properties of its own, such as light weight and rust resistance, and it is widely used in exterior construction such as roof structures and small structures.

Advantages and limitations of galvanised steel

As with black steel, understanding the advantages and limitations of galvanised steel will help you decide better which jobs to use it for.

Advantages : Saves time and is ready to use immediately, because it eliminates the anti-rust painting step

No primer needed

Disadvantages : Carries less load, making it suitable for secondary structures; expensive

To extend the service life of our office units, we use galvanised steel for the main components. For our unit beams, we use black steel because they need to carry heavy loads, and we send that black steel to be galvanised to prevent rust.