Cause analysis and improvement of edge crack in hot continuous rolling high carbon strip steel 65Mn
High carbon steel 65Mn is prone to edge cracking defects in hot rolling production due to its high carbon content and high hardness.In order to completely solve the edge crack problem of high carbon steel 65Mn,the cause of edge crack defect in hot-rolled high carbon steel 65Mn was analyzed by means of fractography,metallography and hardness examination.Thermal simulation test was also carried out to study the effect of cooling rate on the trans-formation behavior of 65Mn.The results show that cooling rate significantly affects the phase transformation process of 65Mn steel,and martensitic transformation occurs when the cooling rate is greater than 25 ℃/s.Mar-tensite has high hardness and poor deformation ability.During hot rolling,the edges of strip with martensite micro-structure due to a high-rate cooling tend to form cracks under the effect of coiling tension.Improvement measures,such as reducing laminar cooling intensity,increasing coiling temperature and reducing side water spraying,can ef-fectively prevent the edges from overcooling,thereby avoiding edge cracks and improving the uniformity of micro-structure and hardness.
high carbon steel65Mnedge crackcoiling temperaturelaminar cooling
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