Hardened and Tempered Strip Steel

Hardened and tempered strip steel is the basic raw material from which many different components are made. These are mostly spring-type applications ranging from automobile clutch plates to washers, retractor springs and traditional clock springs.

This strip product is normally produced with a normal blue-black (also known as blue-grey) oxidized finish which is fully acceptable in most engineering components. Sheared edges can also be edge dressed and, when required, non-oxidized surfaces produced.

Applications

Hardened and Tempered strip steel is a special type of precision strip that undergoes a series of heat-treating operations to develop high hardness, wear resistance, and tensile strength. The engineering staff at voestalpine Precision Strip WI in Pleasant Prairie has over 60 years of experience in this unique niche of the precision strip industry. The company operates continuous heat-treating furnaces manufactured by EBNER of Austria – the universally acknowledged world-wide leader in this field.

During the hardening process, the strip material is heated to temperatures Quenched and tempered steel strip that are higher than its critical annealing temperature. This allows the strip to achieve a relatively uniform degree of hardness over its entire length. In addition, the tempering process can be controlled in such a manner that the strip will not reach its desired tempering temperature until shortly before it exits the tempering zone.

Tempering reduces the brittleness that results from the initial hardening process, increases toughness, and prevents the strip from becoming too stiff. The resulting product can be used in many applications. Examples include tool production (pliers, wrenches, hammers), spring production, clockwork mechanisms, and automotive components. In these applications, hardened and tempered strip is able to withstand heavy loads and repeated stress. It is also exceptionally durable and reliable, which makes it ideal for construction applications. It is also often used in medical applications such as artificial limbs and prosthetics.

Hardness

As the name suggests this type of steel strip has been heat treated to produce high levels of hardness combined with good tensile and shock resistance properties. This provides the engineering component designer with a route to savings in weight, material and cost without loss of strength.

The process is carried out in continuous production lines at voestalpine Precision Strip WI in Pleasant Priarie using state-of-the-art continuous heat-treating furnaces manufactured by EBNER, Austria. The first of these furnaces heats the strip to temperatures at which it becomes work-hardened, i.e. very hard, but brittle. It is then rapidly cooled, usually in oil or water, to a point below the point at which it would crack. The strip is then tempered (a soak at a lower temperature) to soften it slightly, thereby improving ductility and toughness.

The resulting hardened and tempered strip is generally supplied with sheared edges, with a slightly oxidized blue-black (also known as blue-grey) finish, to allow it to be machined. This is often used in applications such as narrow bandsaw blades where shearing and machining can be performed in-line. However, the Company can provide strip with edge-dressed sheared edges to customer specifications, if required. This eliminates the need for post-heat treatment machining and distortion and allows tolerance on width and thickness to be maintained to a very high level.

Thickness

The thickness of hardened and tempered strip steel plays an important role in the quality of final components in many applications. For example, the tensile strength of the material will vary significantly depending on the strip thickness. The engineering staff at voestalpine Precision Strip WI in Pleasant Prairie, Wisconsin has more than 60 years of combined experience in this particular niche of the strip steel industry and manufactures the hardened and tempered product on state-of-the-art continuous heat-treating furnaces manufactured by EBNER in Austria.

The strip has a standard thickness tolerance of T3 based on the internationally accepted Swedish Tolerance Table. This precise thickness tolerance is crucial to the functionality of parts in many of our customers’ applications and also plays a major role in the process parameters for specialty operations used to manufacture the products.

Hardened and tempered strip steel is a critical engineering material that requires specific heat treatment Tinplate Sheet Manufacturer to achieve its combination of high hardness, strength, and wear resistance. It is commonly used in a variety of applications, including tool manufacturing (pliers, wrenches, and hammers) to support heavy pressures and cutting forces during use. It is also common in the automotive manufacturing industry to make clutch plates, transmission components, and other vehicle components that require a high level of strength and performance. Additionally, the material is frequently used in clockwork mechanisms and other mechanical and timekeeping applications to maintain the elasticity and resilience of springs.

Surface Finish

Surface finish is an important aspect of strip steel production. It affects not only the appearance of the steel, but also its functionality in many applications. It influences the way parts are handled, and how they interact with each other. It can have a direct impact on the performance of specialty operations such as precision stamping and grinding.

Roughness is one of the most commonly specified, measured and analyzed aspects of surface finish. It describes the small, fine irregularities on a metal’s surface caused by manufacturing processes like machining or sanding. This can result in a rougher, more scratched, or duller surface. It can be evaluated using simple visual or tactile techniques or more sophisticated measurement tools such as a surface profilometer.

Waviness is another important aspect of surface finish and refers to the peaks and valleys on a surface. This is typically described using the parameters waviness spacing (Wsm) and waviness height (Wt). Waviness requirements are generally less common than roughness requirements, but can be important in certain applications, such as bearing races.

Tempering is the process of reheating hardened and cooled strip steel to soften it slightly and develop ductility. This can help to prevent the strip from becoming too brittle after being hardened, which can adversely affect its mechanical properties and flatness. The tempering process can be conducted in a continuous line by heating the strip to a high temperature and then cooling it rapidly. According to the invention, the tempering zone is divided into a number of temperature zones, and the strip passes through these zones in such a manner that it only passes through the tempering temperature-producing temperature zone last.