Tempering

Tempering is a low temperature (below A1) heat treatment process normally performed after neutral hardening, double hardening, atmospheric carburizing, carbonitriding or induction hardening in order to reach a desired hardness/toughness ratio.

Benefits

The maximum hardness of a steel grade, which is obtained by Induction Hardening in Faridabad , gives the material a low toughness. Tempering reduces the hardness in the material and increases the toughness. Through tempering you can adapt materials properties (hardness/toughness ratio) to a specified application.

Application & materials

Tempering can be divided into three main groups:

• Low temperature (160-300°C): used for case hardening components and cold working tool steels. Typically, hardness requirement is around 60 HRC.
• Tempering of spring steels (300-500°C): used for spring steels or similar applications. Typically, hardness requirement is around 45 HRC.
• High temperature (500°C or higher): used for quenched and tempered steels, hot working tool steels and high speed steel. The hardness will vary from 300HB to 65HRC dependent on the material.

Process details

The tempering temperature may vary, depending on the requirements and the steel grade, from 160°C to 500°C or higher. Tempering is normally performed in furnaces which can be equipped with a protective gas option. Protective gas will prevent the surface from oxidation during the process and is mainly used for higher temperatures. For some types of steels the holding time at the tempering temperature is of great importance; an extended holding time will correspond to a higher temperature. Depending on the steel grade a phenomenon known as temper brittleness can occur in certain temperature intervals. Tempering inside this temperature interval should normally be avoided. These areas are shown in the steel suppliers steel catalogues, as well as the most suitable temperature depending on hardness requirements.

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What's the difference between single shot hardening and traverse hardening?

There are two methods of heating when using induction: eddy current heating and hysteretic heating. When it comes to hardening, however, the two main types are known as single shot hardening and traverse Induction Hardening in Faridabad. Single shot hardening systems employ the use of rotated components in the induction coil, and the entire area is heated at the same time for a pre-determined amount of time using either a drop quench system or a flood quench system. Single shot hardening is typically used in applications in which no other method will reach the intended result, for example, hardening the flat face of hammers and producing small gears.

Traverse hardening, on the other hand, uses an induction coil for the workpiece to pass through progressively. A following quench spray or ring is used, This process is often used in the manufacturing of shaft type components, including axle shafts, steering components, drive shafts, excavator bucket pins, and power tool shafts. The workpiece is passed through a ring type inductor, which usually features a single turn.

Traverse hardening applications are also used in the manufacturing of certain edge components, including paper knives, lawnmower bottom blades, hacksaw blades, and leather knives.

Ultimately, understanding the processes and details of various induction hardening methods is the key to determining which heat treatment type is best suited for your application needs. For more information about induction heating accessories and other induction equipment for sale, contact Inductwell pvt Ltd

Advantages, Disadvantages of Induction Heat Treatment

The process works on the simple principle that when an electrical current is passed through a conductor, an electro-magnetic field is created around the conductor. The conductor is generally (not in all cases) a coiled copper conductor through which a high-frequency magnetic field is induced to flow through the coil. This sets up a magnetic field around the coil and within the coil. If a steel bar is inserted into the coil, the magnetic flux that is generated will create eddy currents within the surface of the steel bar, which creates heat within the immediate surface of the inserted bar within the conductance coil.

The depth of the heated and hardened surface will be dependent on the carbon content of the steel bar, induction frequency, induction power, residence time within the coil and quench medium.

The steels that can be used for an induction heat-treatment procedure will generally contain approximately 0.3-0.5% carbon. Care needs to be taken with the higher carbon grades for the potential risk of cracking. Chromium can be added to the steel (generally 0.25-0.35%) to interact with the carbon content of the steel and produce surface chromium carbides of Induction Hardening in Faridabad.

It is at this point that the decision should be made if the system will quench with water or a poly-alkaline glycol mixture to reduce the risk of cracking. The Induction Hardening Job Work coil can be designed to accommodate any geometric shape that will allow access to the contour to be heat treated and quenched accordingly.

The following will show some of the advantages and disadvantages of induction heat treatment.

Advantages

•  Localized areas can be heat treated

•  Very short surface heat-up times

• Steel can be pre-heat treated to obtain prior core hardness values

•  Very minimal surface decarburization

•  Very minimal surface oxidation

• Slight deformation (bending); this can occur due to internal residual machining stresses

•  Straightening can be carried out on a deformed bar/shaft; however, care must be exercised

•  Increased fatigue strength

•  Can be incorporated into cell manufacture

•  Low operating costs

Disadvantages

•    High capital investment (however, the investment will be dependent on the degree of automation built into the equipment)

•     Only certain steels can be induction hardened

•     The method is restricted to components having a shape that is suitable for Induction Hardening.