Nizhniy Tagil Iron and Steel Works — “EVRAZ NTMK” JSC (Nizhniy Tagil, Russia):

I. K. Galimyanov, Leading Engineer of Technical Department, Head of the Technological Office of the Heavy-section Shop, e-mail: Ilyas.Galimyanov@evraz.com

The data and results of the study of the effect of the bar macrostructure on the quality of grinding balls have been presented. In the manufacture of grinding balls, the round bar is used. When rolling on a ball rolling mill (BRM), metal deformation occurs in rolls with helical grooves at the two grinding balls production areas: at the BRM of a heavy-section shop (HSS) and at the BRM of a rail and beam shop (RBS). Descriptions and differences in the composition of main equipment and the technological production process at different areas have been given. The aim of the study is to research the infl uence of the bar macrostructure on the quality and performance of grinding balls. When producing grinding balls from continuously cast billets (CCB) without degassing at the HSS BRM, there were no cracks and splits. When producing grinding balls from CCBs without degassing at the RBS BRM, cracks and splits of the balls were detected during impact testing of the balls. Flakes were detected in the macrostructure of balls and their bar. When passing balls through a quenching unit and after complete cooling, the martensitic structure of the metal in the presence of flakes results to an increase of internal cracks and cracking of the balls. The technological parameters of the production of grinding balls have been given.

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