Heat Treatment of Steel Billets and Steels
Steel is a type of metal produced by adding carbon alloy and other elements to iron to make it stronger, more durable, and less vulnerable to rust and corrosion. Hot-rolling is the process of forming of steel billets or steels through the process of heating and cooling, which helps to improve the properties of the steel such as strength, ductility, and wear resistance in addition to making them harder and stronger. In order to produce required properties – sometimes even in the form of complex shapes – heat treatment of steel billets and steels plays a vital role. This heat treatment is essentially a combination of various methods such as heating, cooling, and other possible hardening treatments to alter the chemical, physical and mechanical properties of the steel.
One of the most widely used heat treatment processes for steel billets and steels is annealing. This process involves slowly heating the steel to a desired temperature and then slowly cooling it. This process releases internal stresses in the material, relieves cold-working strain, and removes residual martensite. As a result, the steel is softened and made less brittle. This process further improves the machinability of steel and helps to restore ductility and the formability of the material. It also enhances the corrosion resistance of steels which had been exposed to environmental stresses or has machined surfaces.
Quench and tempering is another important heat treatment process used in steel billets and steels. It is a combination of hardening and tempering, which helps to increase the strength as well as the wear resistance of the steel. The process involves heating the steel to above the critical temperature and then rapidly cooling it with the help of a water or oil bath. It helps to refine the grain structure of the steel and provide it with additional hardness. Tempering is the process of reheating the steel after quenching – sometimes followed by air cooling – to reduce its hardness and increase the strength, ductility, and toughness of the steel. Tempering also increases the malleability of steel, making it easy to be cut, formed, and worked for various applications.
Aging or precipitation hardening is yet another method of heat treatment used to enhance and modulate the strength of steel. It involves slow cooling of certain steels at certain temperatures between 20 ℃ to 100 ℃. During this slow cooling, a series of fine precipitates of other alloys are formed that strengthen and harden the steel. This process increases the strength of the steel without sacrificing too much of its ductility.
Heat treatment is an essential step of metallurgical transformation of steel billets and steels. It is used to manipulate steel properties and make them more suitable for various applications. Heat treatment methods such as annealing, quench and tempering, and aging will be used, depending on the requirements of the metal. The use of these heat treatment processes in steel billets and steels effectively helps to produce desired qualities in their mechanical and chemical properties.
