REDUCTION OF SURFACE DEFECTS AND OPTIMIZATION OF CONTINUOUS CASTING OF 70MnVS4 STEEL

摘要

High-strength steel 70MnVS4 is often used for forging connecting rods in the automotive industry. Connecting rod performance depends also on surface quality. Several defects, including surface defects, originate from the continuous casting process. The paper presents the monitoring of the most influential parameters (casting temperature, type of mould steel jacket, casting speed, water flux in the mould and the difference between input and output water temperature in the mould) during continuous casting of 70MnVS4 steel. Also the results of surface control of the rolled material (automatic control line) were collected. Using the gathered data, the model for predicting the ratio between material with surface defects and the examined material was developed using linear regression and genetic programming. Based on modelling results, only one type of mould steel jacket was used, while casting speed and mould water flow were increased from 1.13 m/min to 1.18 m/min and from 1300 l/min to 1500 l/min, respectively. In the period from January 2015 to October 2018 the scrap rate of 70MnVS4 and overall scrap rate was reduced by 22.29 % and 18.04 %, respectively.