22．22mm极限规格X70级热轧卷板的开发

通过适当的控轧控冷工艺，太钢在2250热连轧机组上成功开发了极限规格22．22mm×1550mm×C的X70级热轧卷板，所开发的管线钢30°方向屈服强度达到520MPa，-20℃冲击功达到280J，0℃平均落锤撕裂面积为90％，性能均达到了试制目标，可用于制造大直径、大壁厚的螺旋埋弧焊管，可承载10MPa以上的高压输气。

Development of Limit Thickness 22.22mm X70 Grade Hot Rolled Coil

Through appropriate process of control rolling and cooling,the X70 grade pipeline steel of limit thickness 22.22 mm × 1 550 mm × C was developed by TISCO. The yield strength of the coil（ 30° to the rolling direction） is 520 MPa, the charpy V-notch impact absorbed energy reaches 280 J at -20 ℃ ;the average shear area of DWTI＇ is 90% at 0 ℃. The property of pipeline steel has reached trial production target ,and this steel can be made into large SSAW pipe to transport high pressure gas over 10 MPa.