Quenched and Tempered Steel Plate
After the hardening process, the steel must be tempered to decrease its hardness and increase its ductility. This is done by reheating the metal to a lower temperature for a specified period of time.
Quenched and tempered plate is commonly used in equipment that must endure harsh working conditions. This article will explore what Q&T steel is, the grades stocked by Leeco Steel and typical applications.
High Strength
In environments where equipment is subject to heavy impact and abrasion, designers and engineers may use high-strength quenched and tempered steel materials. These materials have been heat-treated, a process that intensely heats and cools a material to alter its physical properties, to enable it to withstand severe impact and wear.
In the heat treatment process, the steel is heated to a temperature above its critical point and then quickly cooled in water. This rapid cooling, known as quenching, causes a transformation in the crystalline structure of the steel and leaves it much harder. However, this hardness can make the steel brittle in applications where stress is applied repeatedly and could result in failure.
To reduce the hardness and increase ductility, the Steel is tempered. During tempering, the unstable martensite that forms in quenching decomposes into ferrite and stable cementite, and various stages of a microstructure called tempered martensite form as well. The tempered microstructures are usually laths (strips) or plates, sometimes appearing acicular (needle-like) or lenticular (lens-shaped).
This process also improves the fatigue performance of the Steel. The rearrangement of defects during tempering creates dislocations that prevent the formation of new crystal structures and can reduce crack propagation. This makes the Steel more resilient to stress cycles, increasing its quenching and tempering of steel useful life and reducing maintenance costs. It also has a lower coefficient of expansion, which can help to reduce stresses that occur in areas with a wide range of temperatures.
High Durability
Quenched and tempered steel is a durable material used in applications where abrasion or impact are significant. These include machinery, mining equipment, cranes (mobile and loader), aerial platforms and truck and trailer frames. Its durability is the result of a combination of heat treatment and tempering. This process increases a metal’s hardness and strength while increasing its ductility. It also makes it more resistant to fatigue and cracking.
The steel is heated to 850 to 900 degrees Celsius and then quickly cooled, which is known as quenching. This creates a martensite microstructure and significantly increases the strength of the steel. It also reduces the ability of the dislocations in the microstructure to move, which increases a material’s ductility and toughness.
This process also enables larger cross-sections to be hardened than would be possible in unalloyed steels, which have a limit on their cooling speed. When the cooling speed reaches this limit, the workpiece is no longer able to form fully hardened martensite and only becomes hard across its surface.
The global quenched and tempered steel market is competitive, with manufacturers focusing on production Tinplate steel coils Manufacturer efficiency to lower their cost. They are also embracing advanced technology and automation to streamline their operations and enhance their product quality. Additionally, they are focusing on sustainable practices to reduce their carbon footprint.
High Abrasion Resistance
Quenched and tempered abrasion resistant steel plate (also known as wear plate) is a high strength grade of steel that significantly increases the lifespan of components exposed to abrasive conditions. It’s commonly incorporated into fabrications like excavator buckets, bulldozer blades, abrasion-resistant liners for mine machinery and dump trucks, line pans and tipper truck bodies.
To achieve this level of abrasion resistance, the steel must go through a heat treatment process known as quenching and tempering. This involves heating the metal to a temperature above its melting point, then immediately cooling it. The rapid cooling creates a hardening effect, transforming the original pearlite microstructure into martensite. The increased hardness from this process is due to a higher density of defects in the crystal lattice, which prevent dislocations moving within the material.
After quenching, the steel is tempered to reduce its hardness and increase its toughness. Tempering is a controlled reheating of the metal, which causes the defects in the crystal lattice to rearrange into a lower energy state. This results in a decrease in hardness and an increase in ductility.
Due to its superior tensile and yield strengths, high abrasion resistance and formability, Q&T steel is an ideal choice for applications requiring a combination of strength and durability. Leeco keeps a wide range of grades stocked to meet this demand, including abrasion-resistant Hardox® HiTemp – a cost-effective alternative to traditional quenched and tempered wear plates.
Low Weight
Quenched and tempered steels are often used in equipment that requires high-yield-strength materials, as they’re strong but also lightweight. This allows for weight reduction in fabrications, and increases the lifespan of critical components.
The heat-treated alloys also improve machinability, and their toughness reduces internal stresses that can cause failure under load cycling. This is because of the rearrangement of defects that occurs during tempering.
After the quenching process, steel is too hard and brittle for most applications, so it must be tempered to reduce its hardness and improve its toughness. Tempering involves reheating the martensite to a temperature below its critical point, then allowing it to cool in still air. The exact temperature and heating time will vary depending on the steel’s composition and the desired hardness.
When selecting a quenching and tempering method for your steel, consult a specialist to help you determine the best solution for your project. Different methods can produce significantly different grain structures, and the benefits of each will vary. For example, a fast cooling rate might result in an austenitic structure, while a slower temperature and long cooling time might produce a bainite microstructure. Different cooling times can also make a difference in the toughness of the steel, as well as the ductility. Different grades of alloy steel will respond differently to tempering, so it’s important to choose the right one for your application.
