Understanding Mild steel : A technical guide

Mild steel is low-carbon steel made from iron and carbon. It is an inexpensive steel category with properties suitable for most general engineering applications. Due to its high iron content, mild steel has excellent magnetic properties; it is therefore defined as being 'ferromagnetic'.

The carbon content in mild steel ranges between 0.16% and 0.29 % and has a relatively higher melting point between 1450°C to 1520°C. This melting point means that mild steel is more ductile when heated, making it especially suitable for drilling, cutting, forging, and welding, thus easy to fabricate. Register with us to ensure you get the best mild steel for all your fabrication requirements.

However, mild steel is not that suitable for hardening. Only in some instances can it be hardened by heating it, adding a chemically reactive carbon source to it, and the subsequent quench cycle will harden the surface layer. 

Mild steel does not have good corrosion resistance in an untreated form, which, however, can be improved to a significant extent by applying an appropriate surface protection product to the exposed parts of the project. Several options are available in the market to enhance the appearance of mild steel and protect it from rust and corrosion, like red oxide primers, metal paint, metal spray paint, and zinc treatments.

This category of steel is graded as per its chemical composition, the way it is produced, and its properties, so you will have many options of mild steel to choose from basis your requirements. This article will discuss the three most widely used types of Mild steel.

1. Carbon steel - Carbon steel is the most commonly used type of mild steel, given its high strength-to-weight ratio. Carbon steel is divided into four types based on the amount of carbon content present in it: 

· Class C (0.3% or less)

· Class M (0.3% – 0.6%)

· Class S (0.6% – 1%)

· Class P (1%-1.5%). 

Class C is used for most applications because it provides high tensile strength. However, class C carbon steel can be susceptible to corrosion when exposed to moisture for an extended duration without proper protection.

2. High-Strength Low Alloy Steel - Compared to normal carbon steel, high-strength low alloy (HSLA) steel delivers more strength without compromising ductility, weldability, or toughness. Due to its resistance to corrosion, fatigue cracking, and heat damage, HSLA is frequently utilised in applications where durability is crucial, such as bridge construction or military equipment. Due to its lower carbon content than other steels, HSLA is also less expensive than other varieties of mild steel, enabling more effective production methods.

3. Alloyed Mild Steel - Alloyed mild steel contains additional elements such as manganese and silicon, which enhance its strength while maintaining malleability and ductility properties similar to those found in regular carbon steels. Alloyed mild steels are particularly popular with manufacturers because they provide an inexpensive way to strengthen parts while retaining their resilience under loads compared to harder alloys such as aluminum or stainless steel.

Advantages of Mild Steel

• Cost – Both hot-rolled and cold-rolled mild steels are cost-effective for many applications.

• Range – Mild steel products come in vast shapes and sizes, from sheet and plate to bar and sections.

• Recyclable – Mild steel can be effectively melted down to be recycled and reused.

• Weldable – Mild steel is super easy to weld 

• Ductile – Mild steel is ideal for deep-drawing procedures because it can be stretched and shaped easily

Disadvantages of Mild Steel

• Mild steel has poor corrosion resistance, which is its principal drawback. It, therefore, requires an additional finishing procedure to increase its longevity and offer long-term protection. 

• Due to its low carbon content and low tensile strength, it is unsuitable for load-bearing applications, such as buildings or other civil engineering projects.

How to finish mild steel fabrications

Since mild steel has low corrosion resistance, it needs to undergo a final finishing process to give the finished product long-term protection and longevity. The most typical finishing procedures are:

• Powder Coating: The steel's surface is covered with a dry powder, which is then baked on. This results in a tough, long-lasting finish impervious to mechanical and chemical harm.

• Wet Painting: To shield the steel from the weather, a coat of paint is given to the surface.

• Hot dip galvanising involves dipping the steel in molten zinc and letting it cool. This creates a shield of defence against corrosion and rust. 

Many other finishes can be used, but these are the most common. 

Summary

Due to its adaptability and affordability, mild steel plays a crucial role in many industries worldwide. Depending on your requirements, various types of Mild steel are available, including carbon steels, HSLA steels, and mild alloyed steels, each of which has its advantages over materials like stainless steel or aluminium alloys. Regardless of the type of steel you select, you need to ensure that you get a high-quality product that will last for years.

JSW One MSME specialises in supplying high-quality mild steel. Reach out to us for more information.