Hardened Spring Steel Strip

Spring steel is a name given to a wide range of steels used in the manufacture of springs, prominently in automotive and industrial suspension applications. These steels are generally low-alloy manganese, medium-carbon steel or high-carbon steel with a very high yield strength. This allows objects made of sprung steel to return to their original shape despite significant deflection or twisting.

Cold Rolled Spring Steel Strip

cold rolled strip is a steel product that is produced from a hot rolled strip that has been pickled. The coil is then reduced by a single stand cold roll steel mill straight away or reversing mill or in a tandem mill consisting of several single stands in a series. The strip is reduced to approximately final thickness by cold-rolling directly, or with the inclusion of an annealing operation at some intermediate thickness to facilitate further cold reduction or to obtain mechanical properties desired in the finished product. High carbon strip steel requires additional annealing and cold reduction operations. The coil is then slit to the desired width through the process of roll slitting.

Controlled Atmospheres Annealed (Bright Annealed)

The high temperature of annealing may result in oxidation of the metal's surface, resulting in scale. If scale must be avoided, annealing is carried out in a special atmosphere, such as with endothermic gas (a mixture of carbon monoxide, hydrogen gas, and nitrogen gas). Annealing is also done in forming gas, a mixture of hydrogen and nitrogen.

Water Quench Harden Spring Steel Strip

Quench hardening is a mechanical process in which steel and cast iron alloys are strengthened and hardened. These metals consist of ferrous metals and alloys. This is done by heating the material to a certain temperature, depending on the material. This produces a harder material by either surface hardening or through-hardening varying on the rate at which the material is cooled. The material is then often tempered to reduce the brittleness that may increase from the quench hardening process.

Patented Harden Spring Steel Strip

Spring Strip of high-carbon steel with a carbon content of approx. 0.76%C designed for hoisting ropes to be used in the mining industry should have the proper tensile strength,i.e.1800+100 MPa. The intermediate strip must therefore undergo the patenting process to eliminate the cold work effects and to obtain a material structure susceptible to large plastic deformations of up to 95%, consisting of fine pearlite with a high scattering of dispersion cementite. Patenting consists in two-stage heat treatment. At the first stage,the process of wire annealing is conducted at the temperature above Ac3,i.e. in the temperature range from 850 to 1050C.The next stage of the patenting process is an isothermal cooling at the temperature of approx.450-550C in a lead bath tank or in a fluidized-bed furnace.

Applications

• Applications include piano wire (also known as music wire) such as ASTM A228 (0.80–0.95% carbon), spring clamps, antennas, springs, and vehicle coil springs, leaf springs, and s-tines.
• Spring steel is also commonly used in the manufacture of metal swords for stage combat due to its resistance to bending, snapping or shattering.
• Spring steel is one of the most popular materials used in the fabrication of lockpicks due to its pliability and resilience.
• Tubular spring steel is used in the landing gear of some small aircraft due to its ability to absorb the impact of landing.
• It is also commonly used in the making of knives, especially for the Nepalese kukri.
• It is used in binder clips.
• Used extensively in shims due to its resistance to deformation in low thicknesses.

All Grades Comparison

Quality Standard

DIN 17222 Cold Rolled Steel Strips for Springs Technical Conditions of Delivery

BS EN 10132 Cold rolled narrow steel strip for heat treatment. Technical delivery conditions

Chemical Composition(%)

Mechanical Properties(Quenched and Tempered Condition)(T=20°C if not differently stated)

Delivery condition

Cold rolled narrow steel strip covered by EN 10132-4 shall be supplied in one of the following delivery conditions:

-annealed or annealed and skin passed(+A or+LC);

-cold rolled(+CR);

-quenched and tempered(+QT).

NOTE The delivery condition-annealed to achieve spheroidized carbides(+AC)-may be agreed.In such cases,limits on spheroidization and mechanical properties may also be agreed at the time of enquiry and order.

Decarburization

For silicon alloyed steels,decarburization shall not exceed 3 % of the material thickness per side,for non-silicon alloyed steels,decarburization shall not exceed 2% of the material thickness per side when measured at a distance of 5 mm from the strip edge (see also EN 10132-1).

Surface finish

The surface finish of cold rolled narrow steel strip shall be bright as produced by rolling and annealing in a controlled atmosphere.

The surface finishes of quenched and tempered cold rolled strip are as follows:

-grey/blue oxide finish:unpolished;

-brigth tempered:unpolished;

-polished:obtained by fine grinding,abrasive brushing or other processes;

-polished and coloured:blue or yellow colour obtained by oxidization by heat treatment.

Heat Treatment

Mill′s test certificate:

EN 10204/3.1 with all relevant data reg. chem. composition, mech. properties and results of testing