라인파이프용 고강도 열연강판의 기계적 성질

Mechanical Properties of High Strength Hot Strips For Line Pipe Application

The purpose of this study was to investigate the effects of alloying and rolling condition on the mechanical properties and to develop high strength line pipe steels with good toughness. Tests were carried out by the laboratory experiments followed by mill trials and mass production. It was found that a small addition of microalloying elements, such as Nb, V with Mo or Ti remarkably increased the strength and toughness of hot strips. The optimum condition of thermomechanical rolling on low carbon microalloyed steel improved the toughness through the formation of a fine and uniform microstructure. Based on this mill trials following the fundamental research, the production technology of line pipe steels, grade X70∼X100 with high toughness, has been established. These grade steels exhibit excellent low temperature toughness (vTs= under -80$^{\circ}C$) and sufficient strength in both the base metal and the ERW seam weld position, respectively.