Annealing
Annealing is a generic term denoting a thermal process of heating to and at a suitable temperature followed by cooling at an appropriate rate primarily for purpose of softening the metallic materials. . Annealing is carried out for further cold work, machining or to improve electrical properties. The choice of process , cycle and furnace equipment depends upon material, chemical composition, prior thermal history, property and surface quality requirements after processing. In practice, there are different thermal cycles for steel to achieve various goals of annealing. These cycles fall into different categories that can be classified according to the temperature temperature to which the steel is heated and method cooling is used. Few common annealing practices are 'Full annealing', 'Subcritical annealing', 'Spheroidised annealing', 'Intercritical annealing', 'Isothermal Annealing' Annealing' and special processes like Decarburisation annealing etc.

Stress Relieving
Stress Relieving treatment is used to remove stresses residual from other manufacturing steps. The treatment involves controlled heating to a temperature below lower critical temperature, holding for sufficient time and cooling slowly to avoid the introduction of thermal stresses. . It should be noted that the residual stresses couldn't be totally eliminated and reduced to zero. Higher residual stresses and rapid heating during subsequent heat-treating operations (such as hardening) can lead to distortion of the parts.

Normalising
Normailising is a heat treatment process involving heating a ferrous alloy to the austenitising temperature and air cooling to a temperature significantly below the transformation range. Normailising is mainly applied to unalloyed or low alloyed steels. This process refines the grains of the steel that has become coarse in the prior thermal cycling such as hot forging and welding. This grain refinement improves machinability and enhances better response in subsequent heat treatment . In normalising process cooling rate after austenisation is an important factor. Plain unalloyed low carbon steel may be transformed to fine pearlite and ferrite structure after normalising process under certain cooling rate. But low alloyed steels may have bainite and fine pearlite that increases hardness and reduces machinability. Controlled atmosphere heating with controlled cooling can be done in continuous normalising furnace with specially designed various cool section after hot zone, the hardness of the normalised parts designed can be maintained within a close band that improve productivity in machining and consistency of machined part dimensions.

Case Hardening
A generic term covering various processes that are applicable to the steel that changes the chemical composition of the surface by thermo-chemical diffusion processes forming a case. . The diffusion process sets up a chemical gradient that reflects as a hardness gradient. The processes commonly used are 'Carburising', 'Nitriding', 'Carbonitriding', 'Cyaniding', 'Nitrocarburising'. The depth of the case depth upon the process completion time, environment concatenation levels like carbon potential, Nitrogen potential etc. and the material's chemical composition.

Ferritic Nitrocarburising
This process is a thermochemical treatment that involves diffusional addition of nitrogen and carbon. This process is generally done at temperatures below 580°C (1076°F) and usually for 3 hours. It is also called 'short nitriding process'. The essential difference between nitriding and nitrocarburising is that in nitro carburising, the surface compound layer contributes for improved properties while the diffused nitrogen layer is important in nitriding process. All ferrous alloys can be ferritic nitro carburised while only nitrodable steels containing Al, Cr, Mo can be used for nitriding process. The process is done in an atmosphere containing NH3 and a carbon donor such as LP gas, CO2 or Propane at temperatures below 580°C (1076°F). The ferrous material after nitrocarburising need not be quenched if surface hardness is the only consideration. However if the steel after the process is quenched in oil or water, nitrogen is retained in solution in the diffusion zone which contribute for improved fatigue life.
Hardness after Ferritic Nitrocarburising of few ferrous alloys is as follows.

Nitriding
Nitriding is the process of saturating the surface of the steel with nitrogen. Saturation is accomplished in an atmosphere of ammonia gas (NH3) at temperatures ranging 480°C (896°F) to 580°C (1076°F). Ammonia dissociate to nascent nitrogen and hydrogen when in contact with the hot jobs 2NH3®2N + 3H2. Atomic nitrogen formed diffuses into alpha iron and saturate the metal.
Nitrided steel acquire high hardness and retain the hardness even after subsequent heating to 600°C (1112°F). Nitriding increases wear resistance, fatigue and corrosion resistance. Nitriding is usually applied to medium carbon and alloy steels containing carbon and alloy steels containing aluminium, chromine, molybdenum and other elements that are capable of forming nitrides since the process is done at lower temperature, the time cycle will be longer than the caburising cycle. It is preferable to harden and temper the parts prior to nitriding to achieve best properties. The tempering temperature should be minimum of 20°C (68°F) to 30°C (86°F) more thus the nitriding temperature to retain the core properties. The nitrided depth usually between 0.2mm to 0.4mm. No quenching is required as high hardness is obtained directly after this process.

Carbonitriding
In Carbonitriding, ammonia (NH3) is introduced into the carburising atmosphere Ammonia decomposes at carburising temperatures and the steel absorbs the atomic nitrogen. In this process both carbon and nitrogen are diffused together. The essential advantage of nitrogen diffusion is that the case has better hardenability Nitrogen as an austenite stabiliser, reduces the diffusion controlled transformation of austenite to ferrite and pearlite. This higher hardenability allows better control on hardness profiles, use of milder quenchants with lesser distortion. Further this martensite containing Carbon-Nitrogen has better tempering behaviour.
Carbonitriding is generally performed at lower temperatures in the range of 815°C
(1499°F)-900°C (1652°F). Carbonitriding at higher temperatures (more than 900°C (1652°F)) can cause increased retained austenite and even porosity at skin due to higher nitrogen activity. This process is generally restricted to produce case depths below 0.7 mm.

Vacuum Heat treatment
The Vacuum Heat Treatment Process is an advanced, energy-efficient and environmentally friendly. The furnace is equipped with Low Pressure Carburising facility. Digitally controlled flowmeters enable precise carburising gases to be released for accurate carbon diffusion and boost cycles. A variety of chromium, vanadium and Molybdenum alloy steels are most suitably hardened and tempered in a high pressure gas quench chamber of the furnace. A fully automatic sequencing amnd control of the process results in a highly uniform surface hardness and microstructure. It is proven that distortion of jobs is far less in a vacumm heatreatment furnace than in any conventional heattreatment processes.Our furnace is a proven vacuum heat treatment equipment from SecoWarwick Allied with guaranteed process technology.