What Are the Different Properties of White Tempered Steel Strip?
A steel product made from pickled hot-rolled strip that has been cold reduced on a single stand cold roll mill, reversing mill or tandem mill to the exact thickness required. It is then tempered to precisely balance the mechanical properties such as hardness ductility and stiffness.
A lamellar structure found in steel which, on cooling, forms a crystalline ferrite matrix with cementite. The result is a very tough substance with good wear resistance and strength.
Hardness
Hardness is a measure of the resistance of a metal to permanent deformation by application of Wiper blade steel coil force such as indentation. The harder the steel, the greater its ability to resist deformation. It is measured by the amount of force required to indent the steel at a predetermined geometric point. The measurement is generally referred to as the Brinell or Rockwell hardness.
The Company has the capability to produce hardened and tempered strip in both martensite and bainite conditions. These grades are mainly used for spring-type applications ranging from automobile clutches to clock springs and coiled springs in general engineering components. The Company has considerable plant development which allows the production of these grade of hardened and tempered strip in gauges of between 0.10mm to 2.00mm.
Hardened and tempered strip is produced by heating the steel above its critical temperature range in a continuous production line. Then a controlled quenching process is applied to obtain the desired level of hardness, typically to a Rockwell hardness of between 380 VPN and 650 VPN. The next furnace in the production line reheats the hardened steel to a lower temperature to achieve a tempering process. This reheating of the hardened steel develops ductility and toughness. The Company’s hardened and tempered strip is typically supplied with a blue-black (or occasionally blue-grey) oxidized finish which is acceptable for the majority of engineering applications. However, this is also capable of being surface dressed to give a smoother finish where necessary, particularly for applications involving human contact or where the sheared edges may damage any coverings that might be applied to the finished product.
Durability
Stainless steel is an extremely versatile material used in the construction of a vast number of items, ranging from automotive components and aircraft to household appliances and kitchen utensils. A wide range of finishes are available, as well as several different grades and alloys. When selecting a particular type of stainless steel strip, it is important to consider its durability and the specific requirements of the application.
The main characteristics of durable steel are its ability to withstand corrosion, mechanical stress and fatigue. These properties are determined by the heat treatments that steel strip undergoes during production. The most common heat treatment for stainless steel is tempering, a process that reheats the quench – hardened metal to lower its hardness and brittleness. This allows the metal to bend elastically before fracturing, which is necessary in many applications such as springs and tools that require resistance to impact and abrasion.
The durable steels produced by the Company are hardened and tempered to a standardized Rockwell hardness of between C40/45 and C50/55. In addition, they are edge-dressed by an in-line machining process to remove the sheared edges that naturally occur during the slitting and blanking of steel strip into individual lengths. This produces a high quality finished product with an excellent tolerance on edge camber, flatness and a smooth surface free from ‘waviness’.
Strength
When it comes to strength, you want the material that is going to be used in your project to have a high yield and tensile strength. It will also need to be tough enough to withstand repeated stress and shocks. In general, higher carbon steels have greater tensile strengths than lower carbon ones, so if you need the extra strength you might want to choose one of these types of materials.
When a strip is hardened, it goes through a process called tempering. This involves heating the strip to above its transformation range and rapidly cooling it. At this point, the steel is very hard but it is also brittle. The purpose of the tempering process is to give the steel a little more ductility and toughness so it will be able to handle repeated stresses without failing.
Depending on the end use for your metal strip, it might need to be annealed or cold worked before it can be tempered. These processes can make the strip easier to work with and more resistant to corrosion. It Hardened & Tempered Steel Strip Supplier may also need to be ground or polished for safety reasons. This is especially important if you are using the strip for applications such as medical devices or prosthetic limbs where you need the strip to be strong but also flexible.
Roughness
An undesirable feature of a surface that consists of peaks and valleys rather than a smooth, uniform appearance. It is determined by measuring the peak-to-valley roughness averaged over a specified sampling length. Roughness is usually given as a number (RA or Rz) in microinches or in micrometers, although some manufacturers use different standards and units of measurement for roughness statistics.
The degree of elongation in a strip during tempering and rolling is an important factor that determines the capability of the steel for various end uses. Elongation increases as the temperature of the strip is raised, with higher temperatures resulting in greater elongation.
When a wet lubricant is used in the cold-rolling process, the strip may experience additional working roll force that can decrease the amount of elongation. By using a dry lubricant, the added working roller force can be eliminated, allowing the strip to be rolled to a narrower gauge and still achieve the desired elongation.
If the lubricant composition contains water, a chilling step is usually required to bring the moving steel strip to a temperature below its decomposition point before application of the lubricant, and above at least the freezing point of water. This allows the water in the lubricant composition to evaporate more quickly. The steel strip can then be coiled, or otherwise manipulated and further processed (e.g., temper rolling) without losing its dry lubrication benefit.
