INFLUENCE OF ROTARY CCM CASTING WHEEL WORKING SURFACE CONDITION ON STEEL PRODUCT QUALITY

Abstract

The paper presents the results obtained when studying how the condition of the casting wheel working surface in the rotary continuous casting machine (CCM) influences the quality of copper metal products on the Southwire modern high-tech continuous casting and rolling line at PJSC «Artemovsk Non-Ferrous Metals Processing Works». Industrial research identified the main defects occurred on the casting wheel working surface during its operation: transverse cracks located on the working surface in planes perpendicular to the casting direction – both at the trapezoid base and on its side faces (10–45 mm long cracks located 7–40 mm apart); dents, longitudinal dimples and scratches along the direction of billet movement mainly in the obtuse angles of the trapezoid and in areas adjacent thereto; deformed wheel profile in the corners of the working channel, primarily due to friction wear. It was found that the main causes of surface and internal cracks in the wheel are challenging temperature modes of operation associated with the technology of copper casting on the rotary CCM. Alternating cycles of heating and cooling of individual sections of the casting wheel cause two-dimensional tensile stresses in its internal layers resulting in cracks. An equally important factor in crack formation is further excessive secondary cooling of the wheel with water as it is followed by reheating of the billet surface. However, a lowered temperature gradient of the wheel surface between the cooling areas will reduce the degree of surface deformation, increase the service life and improve the quality of continuously cast billets and finished steel.