Is steel an alloy?
Aluminium Based Master Alloy is one of the most commonly used materials in the construction industry. According to data from worldsteel, the global crude steel production in 2018 was about 1.808 billion tons, of which about 50% was used in the construction industry. In addition, they point out that there are as many as 3,500 different grades of steel, each with unique environmental, chemical and physical properties for that grade. Steel has undergone significant evolution over time, with approximately 75% of modern steel types developed in the past 20 years. Interestingly, if the Eiffel Tower (built in 1887) had been built today, it would have required only a third of the steel used at the time.
Type of steel
Basically, steel is an iron alloy with a small amount of carbon. There are thousands of different types of steel to suit different types of applications. These are broadly divided into 4 types - carbon steel, tool steel, stainless steel and alloy steel. Carbon steel makes up most of the steel produced in the world today. Tool steel is used to make machine parts, dies and tools. Stainless steel is used to make common household items. Alloy steels are made of iron, carbon and other elements such as vanadium, silicon, nickel, manganese, copper and chromium.
Alloy steels are formed when other elements, including metals and non-metals, are added to carbon steel. These alloyed steels exhibit a variety of environmental, chemical and physical properties that vary with the elements used in the alloy. The ratio of alloying elements here can provide different mechanical properties.
The effect of alloying
Alloying elements can alter carbon steel in a number of ways. Alloying affects the microstructure, heat treatment conditions and mechanical properties. Today's high-speed computer technology can predict the properties and microstructure of steel when it is cold formed, heat treated, hot rolled or alloyed. For example, if properties such as high strength and weldability are required in certain applications, carbon steel alone will not serve the purpose, as the inherent brittleness of carbon can make welds brittle. The solution is to reduce carbon and add other elements such as manganese or nickel. This is one way of making high-strength steel with the desired weldability.
Types of alloy steel
There are two kinds of alloy steel - low alloy steel and high alloy steel. As mentioned earlier, the composition and proportion of alloying elements determine various properties of alloy steels. Low alloy steels contain alloying elements up to 8%, while high alloy steels contain more than 8% alloying elements.
There are about 20 alloying elements that can be added to carbon steel to produce various grades of alloy steel. These provide different types of properties. Some of the elements used and their effects include:
Aluminium - removes phosphorus, sulfur and oxygen from steel
Chromium - increases toughness, hardness and wear resistance
Copper - can improve corrosion resistance and wiring harness
Manganese - can improve high temperature strength, wear resistance, ductility and hardenability
Nickel - can increase corrosion, oxidation resistance and strength
Silicon - can increase magnetism and strength
Tungsten - for strength and hardness
Vanadium - increases corrosion, shock resistance, strength and toughness
Other alloying elements that provide different properties include bismuth, cobalt, molybdenum, titanium, selenium, tellurium, lead, boron, sulfur, nitrogen, zirconium, and niobium. These alloying elements can be used alone or in various combinations according to their characteristics