Discussion on isothermal normalizing of forging steel billet used to make gears of automobiles;

When carburizing automobile pinion parts made of 20CrMoH steel were treated by isothermal normalization,the cooling rates at various sections during the cooling process before isothermal normalizing and after austenitization were in disparity because of complexities of the pinion sections,which lead to diversity of microstructure and non-homogeneity of hardness at different sections.

After analyzes the influence of automobile cemented gear rough,which is adopted the method of utilizing the residual forging heat for normalizing and isothermal normalizing,on it's structure,hardness,and distortion during cementation and quenching,the feasibility and necessity of the way of utilixing the residual forging heat for isothermal normalizing as pre-heat treatment are determined.

Test of isothermal normalization and its application in the part blanks of gear box were investigated in this paper The results show that the part blanks treated by isothermal normalization have a finer grain size,more homogeneous microstructure than these treated by conventional normalization.

This paper introduces automatic production line for isothermal normalization with residual heat from forged steel parts and installed computer distributed control system,(which can be used for heating up gear billet and normalizing isothermally for the second time)developed by our company,which form a complete set with AMP70 hot former made in Switzerland.

A new forge residual heat isothermal normalizing technique to improve the product quality and save energy;