Quenched and Tempered Steel Plate
Quenched and tempered steel plate is heat-treated to give it the necessary hardness and durability for construction and manufacturing applications that need to withstand severe impact and abrasion. Learn more about this common material type stocked by Leeco Steel.
The quenching process involves heating the steel to an extremely high temperature and cooling it rapidly with water or inert gases like nitrogen. Cooling rates can vary from place to place and can affect the resulting microstructures and mechanical properties.
Hardness
A hardened surface is important for many applications, including tool steels and gear wheels. The workpieces in these cases must be very wear-resistant, which only a hardened microstructure can provide. Quenching and tempering achieves this.
This heat treatment process is often used to make tools, but it also offers advantages for industrial production. It increases the formability and machinability of steel, and it makes the material resistant to stress fatigue. The improved fatigue performance is a result of the rearrangement of defects during tempering.
The hardness of a quenched and tempered steel plate is dependent on its carbon content. The lower the carbon content, the less hard the material will be. However, this can lead to a weaker impact toughness. The quenching and tempering process is able to compensate for this weakness by increasing the hardness of the steel.
To reach a high level of hardness, the cooling rate during quenching must be very fast. However, this can Quenched and tempered steel plate cause thermal stresses in the workpiece. If these are not relieved, the material may become warped.
Tempering is a process that reduces the hardness of the quenched material without affecting its strength. To achieve this, the steel is heated to a temperature below its critical point for a specified time and then cooled in still air. The temperature of the tempering process is determined by the desired hardness and mechanical properties.
Toughness
Quench and tempering is an important step in high-strength steel production. It reduces hardness, increases toughness, and improves weldability. It also creates a stronger, more resistant product to abrasion and impact. It is commonly used in construction equipment, dump trucks, and mining applications.
The toughness of a material depends on its ability to bend under stress. The atoms in a metal can be rearranged to form different crystal structures during the quenching process, which increases toughness and allows the metal to absorb more energy without damage. The process is controlled by the temperature, agitation, and water content in the quenching medium.
A higher level of dislocation density is another factor in toughness, which is a property of the crystal lattice structure. Dislocations prevent plasticity by hindering the movement of atoms through the material. This increase in toughness is also a result of the increased densities of defect particles created during the quenching process.
Tempering is the process of reheating the quenched metal and holding it for a short period of time. This reduces the hardness of the martensite, resulting in a softer, more flexible metal with improved ductility. The reduction in hardness during tempering also results from the rearrangement of defects in the crystal lattice. These changes help to improve the fatigue performance of the material, which is a common failure mode in many types of machinery.
Durability
For equipment that needs to stand up to severe impact and abrasion, project engineers may turn to quenched and tempered steel plate. This heat-treated material is incredibly durable, but also highly machinable and weldable. The process involves bringing the steel to an extremely high temperature and immediately cooling it with water. Leeco carries various grades of this material and keeps them stocked for construction companies and manufacturers who use it to build heavy-duty machinery.
During the quenching process, steel gets heated to its critical (austenitic) temperature and then cooled quickly in water, oil, forced air or inert gases like nitrogen. Various parameters such as heating temperature, cooling method and cooling speed get monitored during this Tinplate Sheet Manufacturer time to ensure the desired hardened state is achieved. Once the steel is quenched, it’s then tempered to attain greater toughness and ductility by decreasing its hardness.
The tempered material is still hard, but it has a much lower stacking-fault energy than martensite or pearlite, and it’s not as brittle as untreated steel. The resulting material is ideal for construction, manufacturing and transportation applications where equipment must withstand severe impact and abrasion. The high yield strength of these materials also means they can be built lighter than conventional, non-heat-treated metals. This reduces the weight of equipment and lowers costs for shipping and installation.
Weldability
Quenching and tempering change the structure of the steel plate, making it very hard and brittle. This makes it difficult to weld. However, it is possible to weld these types of steels if the proper welding techniques are used. These techniques require a low heat input that prevents the formation of a hardened weld zone (HAZ).
Welding a steel that has been quenched and tempered requires special care to prevent the formation of defects in the weld area. These defects can lead to a loss of impact strength in the weld area. To avoid this, the welding process must be carefully controlled and a filler material that is compatible with the steel’s hardness and strength should be used.
The weldability of Q&T steels depends on the alloying elements used in the construction of the plate. Some of these alloying elements are chromium and molybdenum, which increase the strength of the steel plate by changing the way the structure forms upon cooling. These high strength steels have a reputation for being difficult to weld, but this can be overcome with proper welding technology and a matching filler metal.
The heat-treated, high-yield-strength plates stocked by steel plate suppliers like Hansen Steel are ideal for use in applications requiring heavy-duty equipment that must withstand impact working conditions. They are commonly seen in crane manufacturing and the construction of large heavy-load machinery.
