Industrial development of wide and thick plate X65 pipeline steel

The 20.62mm thick X65 trial was carried out on the production line of wide and thick plate. The microstructures, inclusions and mechanical properties were studied by scanning electron microscopy and optical microscopy, low magnification and impact were shown that: (1) The wide plate X65 slab center area is severe and the degree to C level.(2) Inclusions in the finished product is mainly alumina oxide, silicate and composite inclusions, large-scale abnormal non-metallic inclusions were not found.(3) After the first rolling with the microstructure is relatively uniform and small acicular ferrite, grain size acts as 12 grades while the thickness has the center of a slight negative segregation zone, the mechanical properties are to meet the standard requirements but less margin.(4) After adjustment about the second time on the Mn, V composition and rolling process, Compared with the first batch of steel, the yield strength is more than 20 MPa, which fully meets the requirements of X65.