ETHYLENE CRACKING FURNACE TUBE HAVING EXCELLENT RESISTANCE TO COKING AND PRODUCTION THEREOF

摘要

PURPOSE:To obtain ethylene cracking furnace tube having high strength at high temperature, excellent processability, welding property, etc., and resistance to coking by including individually specific amounts of Cr and Ni and specific finely pulverized layer. CONSTITUTION:Steel tube containing 15-30wt.% Cr and 15-50wt.% Ni is subjected to cold forming of =20% degree of forming or cold forming from the surface to =50mum depth and resultant tube is heated to =1100 deg.C in an atmosphere containing 5vol.% oxygen and =20vol.% nitrogen to afford the aimed ethylene cracking furnace tube having a finely pulverized layer of No.7 or more particle size of austenite crystal to =30mum depth from the surface.