Reason Analysis and Technology Improvement on the Cold Drawing Fracture of 55 Round Bar
Through the macroscopic examination,HRB hardness analysis,metallographic analysis,electron microscope analysis of fracture,drawing strength calculation etc.of the guide rail,the reason of the cold drawing fracture of 55 Steel was analyzed.The analysis showed the core crack emerged caused the drawing fracture in the steel due to the shrinkage cavity in the billet which was not rolled down completely.Against the problem of the shrinkage cavity,the continuous casting light pressure was used in the billet production.When the billet of the technology improved was rolled to Φ70 mm size round bar,the inernal quality of the products fully met level A requirement of UT and customer use showed the products also met the use requirements of the customer which achieved the good economic and social benefits.xperience of rapid recovery of furnace condition,and describes in detail the measures to prevent nodulation in blast furnace.