Steel is everywhere in our daily lives. It can be found in the stainless steel utensils in our kitchens, the steel bars in construction, and the parts and components in mechanical equipment. It is deeply integrated into our lives. Let’s learn more about this ubiquitous guy – steel – in this article.

What is Steel?

Steel is really a mixture of iron and carbon. If you know the iron-carbon phase diagram, you know that metals with carbon contents between 0.0218% and 0.211% are collectively referred to as steel. Of course, the steel we use in our daily lives also contains other elements, such as nickel, chromium or manganese, to change the properties of the steel to meet specific usage requirements.

EVERGREEN customers like to use steel for products such as server racks, fasteners, gears and propellers because of its properties: high strength, good plasticity and toughness. Steel is also an environmentally friendly material with a recycling rate of up to 60%.

How is Steel Made?

Currently, there are two main methods of steelmaking: the traditional blast furnace-converter (BF-BOF) and the electric arc furnace (EAF). The essential difference between these two methods is the type of raw materials and energy used.

Blast Furnace-Converter（BF-BOF）

BF-BOF is a two-step process. First, iron ore, coke and other materials are fed into a blast furnace, where iron is extracted from the iron ore through a high-temperature reaction to produce industrial-grade iron.

This method mainly uses coal as an energy source, and the process is relatively cumbersome and causes relatively high environmental pollution. However, due to its high production efficiency, 70% of the steel on the market is currently produced by this method.

Electric Arc Furnace（EAF）

EAF This process is relatively simple. Its raw materials are mainly recycled steel scrap, which is melted at high temperatures in an electric arc. Some metallic elements can be added during the process to adjust its properties.

Since it is heated by an electric arc, there is no waste gas, so the EAF steelmaking process is more environmentally friendly. However, its steelmaking efficiency is relatively low, with only about 30% of steel being produced by this method.

Properties

Next, let’s take a look at the properties of steel. There are roughly three properties of steel, which will be introduced in detail below, with examples of the most representative models.

Strength

The strength of steel represents how much load and pressure it can withstand, and the higher the strength, the greater the load capacity. The strength of steel is measured by its tensile strength (the maximum stress that steel can withstand when subjected to tensile force), yield strength (the minimum stress at which plastic deformation of steel begins), and hardness. The higher the value of these three items, the higher the strength.

High-strength steel includes Q355, which is a type of HSLA (high-strength low-alloy) steel. Q355 is hard because manganese is added during the refining process, which is why it is also called manganese steel. Most of this type of steel is used in industries that require high strength, such as construction, bridges, automobiles and ships.

Ductility

The ductility of steel refers to the fact that steel will deform under the action of external forces without breaking. Similarly, steel with high ductility also has good plasticity (the ability of steel to be pressed or forged into the desired shape) and can be processed into the desired shape by forging, stretching or bending.

Ordinary carbon steel has very good ductility, such as Q235, which is very suitable for making frames and some structural parts.

Corrosion Resistance

Corrosion resistance refers to the situation where steel is not prone to oxidation and rusting when exposed to the natural environment or in contact with some corrosive liquids for a long time. In order to improve the corrosion resistance of steel, metal elements such as chromium and nickel are generally added during steelmaking, or parts are surface-treated by painting or galvanizing.
The most representative examples are the stainless steels we are very familiar with, such as 304 and 316. They can be found in kitchens, hospitals and food processing plants.

Advantages of Steel

First and foremost, steel has the most advantageous benefit: sustainability. It can be said that steel is the metal with the highest recycling rate in the world. Since it does not lose any of its previous properties during recycling (for example, if it was previously Q355 steel, it will remain Q355 after recycling, and you do not need to adjust it), it can be recycled indefinitely.
Another prominent feature is that steel is sturdy and durable, and it can be used in a wide range of applications. It can be found everywhere in our daily lives, and it is a metal material with excellent cost performance.

Disadvantage of Steel

First of all, a prominent disadvantage of steel is its weight. Steel is much heavier than some other alloys for the same volume. This means that steel is inferior to those lightweight alloys in some applications, such as the aerospace and automotive industries, where lightweight designs are required.
Another major disadvantage is that, with the exception of stainless steel, all other types of steel are prone to rusting, as they contain more than 99.7% iron, which readily reacts with oxygen in the air. However, this can be improved by surface treatments such as galvanizing or painting, which however also increase the cost.

Steel Types

If you have read this far, you must be very interested in steel. There are many subcategories of steel, which can be classified according to different uses or alloy compositions.

Stainless Steel

Stainless steel is often used in places with harsh environments or in beverage and beer processing plants. One of the purposes of using stainless steel is to prevent corrosion. Due to the addition of about 10% chromium and nickel, its properties are very stable and it is not easily eroded.
Another is that stainless steel is non-toxic and non-polluting, so many medical instruments and equipment are made of stainless steel.

Carbon Steel

Carbon steel is a relatively simple alloy containing only iron and carbon, with no other unnecessary elements. The carbon content ranges from 0.2% to 2%, and can be divided into low carbon steel, medium carbon steel, and high carbon steel according to the carbon content.

The carbon content directly determines its strength, hardness and other properties. The higher the carbon content, the higher the hardness and strength, but it will be brittle and break easily. The lower the carbon content, the opposite is true.

Alloy Steel

Alloy steel is steel to which one or more other elements are added to change some of its properties for different purposes. The proportion of these elements added is between 1% and 50%. If the proportion of other elements is less than 8%, it is called low-alloy steel, and if it is more than 8%, it is called high-alloy steel.
Alloy steel can be used for various purposes, but its manufacturing cost is high. The following examples of tool steel, weathering steel, electrical steel and high-speed steel are all types of alloy steel.

Tool Steel

Tool steel is mainly used to make tools such as drill bits, cutting tools and molds, so its strength and hardness need to be very high. It has a high carbon content and a small amount of manganese is also added to greatly increase its hardness.
However, tool steel has poor plasticity, is prone to breaking, and places high demands on the heat treatment process and equipment.

Weathering Steel

Weathering steel was originally manufactured for outdoor use, so that it can remain stable and free from rust in harsh natural environments for a long time. This is thanks to the addition of elements such as chromium, nickel and copper, which can form a strong oxide layer.
Some equipment that is exposed to the elements for a long time, such as railway tracks, bridges, wind power towers, etc., will use weathering steel.

What are The Uses of Steel?

It can be said that steel is involved in almost all fields, and each field uses some of the characteristics of steel to meet specific needs. The most important characteristics are: strength, hardness, impact resistance, wear resistance, plasticity and corrosion resistance.
Industries such as construction, automobiles, machinery manufacturing, energy, tools and equipment, aerospace and daily necessities all rely on steel.

Let Evergreen Make The Steel Parts for You

You can try asking Evergreen to make steel parts for you. We have four production workshops: a casting foundry (sand casting, precision casting, die casting, etc.), a machining workshop, a sheet metal welding workshop and a forging workshop. We can process all kinds of steel parts for you to meet any of your needs. We can also provide surface treatment processes such as galvanizing, powder coating and painting.

Summary

Overall, steel is an indispensable material in our daily lives, permeating every aspect of our lives. I hope that this article will give you a concrete understanding of steel, provide some convenience in your future life, and also add a guarantee to your project.