Effects of Dezincification on Continuous Caster Spray Nozzle Assemblies

摘要

Several instances of "ghost-lines" (surface roughness caused by micro-segregation in cold-rolled and formed automotive sheet product) occurred at a continuous caster at United States Steel Corporation's Gary Works. These incidents were traced to the malfunction of water spray nozzle assemblies (SNAs) in the bender segment. Unusual cracking of some SNAs made of C33000 brass was found to be caused by dezincification, a galvanic corrosion reaction governed by environmental conditions, where zinc leaches away, leaving behind a porous, weak copper-rich material. This paper explores the metallurgy of the dezincification mechanism, and the effects of the SNA cracking on the spray cooling.