After Hardening, tempering is necessary to reduce the brittleness of hardening and achieve the requisite mechanical properties. The material is reheated to tempering temperature between 150^C to 750^C. Similarly Stress relieving is carried to relieve the stress in welded /forged parts, between 400^C to 700^C temperature in the same furnaces, Solution annealing is also done in these furnaces. We have forced air circulation furnaces. If tempering is to be carried out above 600^C, then controlled atmosphere furnace may be used and sealed retort furnaces & salt bath are used when required.