Study On Process, Tecture And Fish-scale-resistance Of DC05EK Cold Rolled Ultra Low Carbon Enamel Sheet

The high quality enameled steel need to have good forming property and fish-scaling resistance. These qualities are closely related to the microstructure, texture and the second-phase particles. High volume fraction of near{111} components is essential for good forming property. Large quantities and dispersion distribution of the second-phase particles is good for fish-scaling resistance.In this paper, texture evolution during hot rolling, cold rolling and annealing of the steel is systematically investigated by means of the X-Ray diffraction and EBSD analysis. The change law of annealing process to mechanical properties and texture and the effective of second-phase particles to hydrogen storage trap is explained by microstructure observation and transmission electron microscope (TEM). The main results are as follows:1) The hot-rolled steel has no orientation, the a-fiber has high volume in cold-rolled steel, annealing is beneficial to the y-fiber. The density and the strength of the orientations are developed with the raise of the anneal temperature and the prolonging of anneal time. When the anneal temperature arrive at850℃and stay at this temperature for60s, the density of y-fiber is the most uniformity.2) The alteration of r (the representation of deep drawability) is equal with y-fiber:it goup with the ascension of strength and uniformity of y-fiber. Both of he raise of the anneal temperature and the prolonging of anneal time can develop the alteration of r of experiment steel. It’s also approved that the cooling speed has no effect on microstructure and properties.3) The hydrogen permeation time reduced with the raise of annealing temperature. When the annealing temperature increased from730℃to850℃, the hydrogen permeation time reduced from about16min to12min; but when the annealing temperature arrived at870℃, the small and diffuse second-phase particles Ti(C,N) dissolved, so the hydrogen permeation time gown to3min sharply.4) When the annealing time is longer than a special time, the hydrogen permeation time will be stable. When the annealing time increased from60s to180s, the heat preservation time is long enough to make the small separation Ti(C,N) grow up together, the hydrogen storage trap reduced, and the hydrogen permeation time gown down rapidly-from12min to4.4min. But when the annealing time go on increasing, the hydrogen permeation time no longer changed.5) The optimum annealing process is annealing at850℃and60s. On this process, the yielding strength is the lowest. Not only the tensile strength and r, but also the y-fiber got to the highest, so the forming property is the best. At the same time, the hydrogen permeation time is the longest and the fish-scale-resistance is the best under this process.