Quenched and Tempered Steel Strip
Quenched and tempered steel is a heat-treated material that offers higher toughness than untreated grades. Typical applications include construction and manufacturing equipment that encounters high impact or abrasion.
Carbon-steel heat-treating behavior can vary significantly depending on alloying elements. Alloys help to avoid the formation of martensite by hindering carbon diffusion during lattice transformation.
Hardening
The process of hardening (also known as quenching) can produce a very high level of mechanical properties. However, such high levels of strength and ductility come at a price: quenching causes large thermal stresses which can cause distortion of components that cannot be corrected by subsequent straightening or machining operations. For this reason, component designers need to consider the impact of quenching on their design early in the development stages.
The main objective of the heat treatment is to obtain a tough material with a high degree of wear resistance. This is Special quenched and tempered spring steel belt for saw blades achieved by quenching and tempering the steel.
A hard, wear-resistant material is essential in applications such as drills and gears where the parts are constantly rubbing against one another. The hardness of the materials is directly related to their strength. In order to achieve this, the steel is hardened through a quenching process at very high temperatures. The high temperature in this case is referred to as the “quenching temperature”.
During the quenching process, the steel’s lattice structure is strongly distorted. This is a result of the formation of martensite, which has much higher hardness than ferrite and cementite. The distorted lattice structure also blocks dislocation movement, which reduces deformation and makes the steel very hard.
The hardening process can be performed in an open furnace (in air) or, for a more controlled treatment, in a protective environment (gaseous atmosphere, molten salt or vacuum). It is possible to further control the treatment by selecting different quenching mediums and tempering temperatures. For example, a martempering treatment can be used on certain alloy steels to avoid scale and decarburisation, while at the same time increasing hardening depth.
For most application, it is sufficient to use a quenching temperature of around 1050 degC. In this temperature range, the steel can be tempered to a hardness between Rockwell C 50 and Rockwell C 72. The precise hardening temperature is determined by the composition of the steel and its section size, as well as the desired mechanical properties.
In order to ensure that the steel has the required mechanical properties, it is important that the section size of the work-piece is accurately measured and the geometry of the part is carefully designed. This will help to avoid stress-raising features such as sudden changes in the section, deep slots or cutouts. In addition, the design of the part should take into account the effect of the temperature and quenching process on the mechanical properties of the steel. This is especially crucial in applications with a high load-carrying capacity.
Tempering
In many cases, a high degree of hardness or strength is required. For example, a file blade needs to be very hard so that it can effectively remove the material from the workpiece without becoming itself blunt or damaged in the process. The same applies to gear wheels, which must be extremely hard at the contact points. These types of Tinplate steel coils Manufacturer applications are often served by tempering, which is a further thermal treatment that adjusts the mechanical properties of the steel.
The general procedure is as follows: the steel is heated to a temperature slightly lower than the hardening point. This is maintained for a predetermined dwell time to allow the transformation of the martensite into austenite to occur. The higher the temperature, the harder the material will be but the tougher it will also become.
Tempering is a heat treatment that takes place after the hardening process in order to reduce the hardness and improve the toughness of the material. This is achieved by reheating the steel to a temperature below its critical point (its transformation temperature) and cooling it quickly.
For the tempering process, a furnace with several different temperature zones is used. The strip is guided through these temperature zones at a speed that depends on the desired hardening temperature and corresponding tempering temperature.
During tempering, the defects that resulted from the quenching process rearrange themselves into a more stable state, thereby lowering the density of these defects and reducing the hardness of the material. The process can also be performed on a smaller scale, for example on individual strips that have been cut from a larger sheet.
Typical applications for tempered steel include tools, automotive components and structural materials. In addition, it is often used in mining and earthmoving industries for products such as cutting edges, crushers, earthmoving buckets and dump truck wear liners. In these areas, the steel needs to be very hard in order to withstand large loads and impact forces. For more information, please contact a Clifton Steel specialist. We’ll be happy to help you find the right product for your application. We supply a wide range of grades, sizes and quantities to suit any requirement. Contact us today to learn more about our tempered steel products.
