Ultra High Strength Steels Hot Rolled and Cold Rolled Hot Dip Galvanized

摘要

This paper shows the strong influence that the production parameters have in the manufacture of ultra high strength steels, and describes how using only one chemical composition, three different hot-rolled grades (S 600 MC, S 650 MC, S 700 MC) and two cold-rolled grades (DP 900 and DP 1100), both hot dip galvanized, were produced. This result is very interesting, not only for the grades developed but also in view of reducing the number of grades produced in the steelplant, thus achieving substantial savings in terms of time and costs. varying this composition the strength of the steel is reduced, improving its forming properties and obtaining the characteristics of grade DP 600 GI. This study is mainly focussed on the influence of the hot-rolled strip thickness and coiling temperature and of the annealing cycle undergone by the cold-rolled and HDG material. Based on laboratory research, the above-mentioned grades were industrially produced. Moreover, the steel grades manufactured were characterized, not only with tensile testing but also with other tests such as fatigue resistance, forming limit curves and welding tests, all of which yielded very good results.