Effect of Ferrite/Pearlite Band Structure on Impact Property of L360N Seamless Steel Linepipe

Analyzed are the microstructures and mechanical properties of the L360N seamless steel linepipe with different heat treatment conditions, i.e., as-hot rolled, 1 hour-normalized at a temperature of 920 ℃, 3 hour-uniform annealed at a temperature of 1 150 ℃, and the combination of the latter two. The band areas and the non-band areas under the four different heat treatment conditions are compared. As a result, it is identified that the band structure of the L360N linepipe-purpose steel can be eliminated by means of long-time uniform annealing treatment at an elevated temperature, and that the band structure of the steel produces little influence on its tensile property, but strongly influences its impact property.