22nd November, 2017

Processes - Normalising, Annealing

Open furnace facilities are available for the annealing, normalising, hardening, tempering and also stress relieving of components. The range of equipment is tailored to the needs of the foundries, precision casters, forgers and fabricators. Electric or gas fired furnaces are available to undertake any of the above operations. A brief synopsis of some of the main treatments offered are given below:

Full Annealing: By correct selection of a heat treatment steel and be softened such that it can be fabricated easily. The characteristics of full annealing are that the temperature employed is above the critical temperature and is then cooled using a very slow rate usually in the furnace.

Normalising: The process is similar to annealing except the steel is cooled at a much faster rate. A fan cooling system is available which exacerbates the cooling rate, refining the grain size and improving machinabilty.

Stress Relieving is the heating of steel to a temperature (usually in the range of 600 - 650°C) primarily to relieve internal stress and thereby prevent distortion or cracking during machining. Additionally post-weld heat treatments using a combination of rampup/hold/cool down temperature rates which can be undertaken by the implementation of programmable temperature controllers into the furnace instrumentation.

Open furnace treatments are accompanied by scaling due to the presence of air in the furnace. Several furnaces are equipped with a nitrogen additions which can be utilised to reduce scaling rates.

Next Page: Rapid Quenching
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