cooling procedure
1.With 40CrNi and 30CrMnSiA steels, as specimens, the rules and the mechanism concerning both the tempering embrittlement caused by slow-cooling applied to high tempering and long duration iso- thermal procedure after high temperature austenization as well as those of eliminating such kinds of embrittlement by intercritical heat treatment (IHT) are discovered in our research work.
2.This paper emphatically described several current process for cold treatment of roll and further described the cold treatment procedure of roll which is based on the adiabatic expansion cooling of compressed air in our group company,the data of deep cold treatment test using this procedure were provided.
3.After 12 h cooling, radiochemical separation is preformed and 17 more elements (Pr, Er, Gd, Nd, Ce, Tm, Cs, Rb, Sb, Zn, Zr, Sr, Ba, Ga, Ta, U and Th) are determined. The separation procedure consist of ion exchange, solvent extraction and reverse phase chromatography, resulting in the separation of 36 elements into 12 groups. A CANBERRA SCORPIO-3000 system is used for γ-ray spectrum measurements and data processing.
4.By employing the procedure of heating atlower temperatures,and rolling in an optimizing process followed by an interupted cooling with acooling rate of 17℃ per second between 780～600℃,the increased yield strength and decreased tr-ansition temperature of 13mm thick 06MnNb steel plates as well as a complex microstructure,cont-aning very fine acicular ferrite(d<4μm),fine M/A inlands and a small amount of granular bainite,were obtained.
