Influence of cooling velocity after coiling on the structure of high strength steel

The characteristics of property nonuniformity and the cooling velocity after coiling of 700 MPa hot rolled steel plates were investigated by means of tensile test, SEM, TEM, energy spectrum analysis and hardness test, and the reasons that cause these characteristics were analyzed. The results show that the strength of the coil intermediate is the highest, but that of the outside is the lowest. There is significant difference in metallurgical structure and precipitation behavior of earbonitrides in the coil intermediate and outside samples, which is the main reason that causes property nonuniformity. The cooling velocity after coiling is an important factor that affects the metallurgical structure and precipitation behavior of carbonitrides.