Bi:metallic steel barrel for continuous casting roller - having external layer of tempered martensite structure stainless steel and inner layer of low carbon manganese molybdenum- niobium steel

摘要

Bimetallic steel barrel for continuous casting roller has an external layer of stainless steel with a tempered martensite structure and an internal layer of a low carbon, manganese-molybdenum-niobium type steel (in which niobium can be replaced by vanadium or tantalum) or a 12 CSDV 7 type steel with a ferrite-rich two phase structure. Barrel is produced by subjecting a bimetallic steel tube to heat treatment at 1050 deg. C for 1 hr, cooling in still air and tempering at 600-650 deg. C for 2-4 hrs. Pref. the original tube is made by centrifugal casting. External layer retards the formation of cracks and the internal layer prevents crack propagation. External layer has a tensile strength of at least 70 daN/sq.mm, a yield strength of at least 50 daN/sq.mm and higher wear resistance than Cr-Mo steels. Internal layer has a tensile strength of greater than 50 daN/sq.mm., a yield strength of at least 40 daN/sq.mm and high ductility.