Forging ring as a typical forged part, the normalizing process is indispensable, and the so-called normalizing process is to heat the steel piece to Ac3 (or Acm) above 30~50 °C for a suitable period of time and cools in still air. The normalizing fire in which the steel piece is heated to above Ac3 and 100~150 °C is called high temperature normalizing.
For the forged ring, the purpose of the normalizing process is to refine the structure. Compared with the annealing, the pearlite layer is finer after the normalizing, the ferrite grains are also finer and the strength and hardness are higher; the hardness is improved by normalizing. It can improve the cutting performance and can be used to replace the quenching and tempering to simplify the heat treatment process in some cases.
Large forgings must be tempered at high temperature after normalizing to eliminate the internal stress generated during normalizing. Some alloy steels produce partial martensite transformation during forging to form hard structures. In order to eliminate this bad structure, the fire temperature is about 20 °C high and heat is maintained for normalizing. The normalizing process of the forged ring is relatively simple, which is beneficial to the use of forging waste heat normalizing, which can save energy and shorten the production cycle.www.morayshaft.com