Development of Dual-Phase Steel Using Non-Peritectic Carbon Chemistry for Thin-Slab Continuous Casting Compact Strip Production (CSP) Steel Mill

摘要

Conventionally advanced high strength steel grades are processed by casting thick (200-250 mm) ingots/slabs of peritectic steel grades with carbon content between 0.09 wt.% and 0.16 wt.%. However, as the worlds steel making technology moves closer to the CSP steel making, this process requires the steel to be continuously casted into thin 65 mm slabs before hot rolling. Continuous casting of peritectic steels to produce thin slabs is often difficult and critical as it may lead to bad surface quality, cracks, breakouts, etc. The current study focuses on developing dual phase steels using grades with non-peritectic carbon content (C<0.08 wt.%) and microalloy addition. The mechanical behavior of such steels is to a large extent a function of the microstructure. The microstructure is in turn a result of the chemical composition and the process parameters during its production. The connection between microstructure and mechanical properties is studied, with focus on the microstructure development after hot rolling and during annealing in a continuous galvanizing line. In-line plant trials have been carried out in order to investigate the impact of alloying elements and process parameters on the microstructure.