The influence of microstructural anisotropy on the delamination of dual phase steels

Delamination is a well known phenomenon that occurs in dual-phase steels. This phenomenon is also evident in 3CR12, which has a dual-phase structure after hot rolling, and this often causes problems when thick plates are cut by shearing. Work on dual-phase and low alloy steels ascribed this delamination to the pancake shape of the grains, which is essentially an anisotropy in grain shape. In work on the delamination of 3CR12 it was shown that this grain shape anisotropy also contributes to the delamination. Crystallographic texture measurements on 3CR12 show that the material has a strong, preferred-orientation in the hot-rolled condition. Texture measurements were carried out with an x-ray diffractometer using Mo radiation. It was found that 3CR12 delaminates as a result of anisotropy in grain shape and the presence of bands of orientations of {l brace}100{r brace}(uvw) and {l brace}111{r brace}(uvw) type textures. However, brittle cleavage was found at an angle of 45 degrees to the rolling direction, which indicates an effect from the crystallographic preferred-orientation. At lower temperatures this effect is enhanced by the formation of large brittle areas at angles of 45 degrees to the rolling plane, a result that can only be explained in terms of crystallographic texture. 12 refs., 14 figs., 1 tab.