Analysis and improvement measures of rewinding broken tape of cold rolled carbon steel
In view of the brittle fracture problem of 65 Mn hot rolled steel strip for cold rolling base material in the process of slitting and rewinding during the production of a saw blade enterprise,the failure reasons were comprehensively analyzed by means of composition analysis,metallographic observation and Brinell hardness test.The results showed that the chemi-cal composition and tensile properties of the brittle fracture steel strip could meet the standard requirements.The Brinell hardness was 244-271HBW with large local fluctuations.The structure was mainly in pearlite with grain size of grade 6.5-7.There was a network or semi network ferrite wrapped pearlite phenomenon,leading to the decrease of grain boundary energy,which was the main cause of brittle fracture.By fully slow cooling or annealing hot rolled coils,the phenomenon of brittle fracture could be significantly improved.Pre-annealing was performed before cold rolling of subsequent steel strips to reduce deformation resistance.The rolling force was stabilized at 10-14 MN,which could significantly improve the cold rolling efficiency and performance stability.
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