The invention relates to an X70 pipeline steel
hot rolled coil and a manufacture method thereof. The coil comprises the following ingredients in percentage by weight: 0.02 to 0.05 percent of C, 0.10 to 0.30 percent of Si, 1.00 to 1.40 percent of Mn, at most 0.015 percent of P, at most 0.002 percent of S, 0.015 to 0.05 percent of Alt, 0.05 to 0.08 percent of Nb, 0.02 to 0.035 percent of V, 0.01 to 0.02 percent of Ti, 0.10 to 0.50 percent of Cr, at most 0.006 percent of Ca, 0.10 to 0.30 percent of Ni and 0.10 to 0.30 percent of Cu. The manufacture method is mainly characterized in that a, the
laser fused (LF) refining is carried out outside a furnace: desulfurization is carried out until the weight percent of S is less than or equal to 0.0015 percent; b, the RH refining is carried out outside the furnace: Ca-Si lines are added before the vacuum
smelting and steel outlet; c, the
continuous casting temperature is 1553+ / -15DEG C; d, the
continuous casting pulling speed is higher than or equal to 1.0 m / min; e, the plate blank
heating temperature is lower than or equal to 1200 DEG C; f, the rough rolling terminating temperature is 930 to 1030 DEG C; g, the finish rolling terminating temperature is 780 to 850 DEG C; h, the steel band coiling temperature is 450 to 580 DEG C; and l, the
cooling speed of the layer flow cooling is higher than or equal to 5 DEG C / s. The X70 pipeline steel
hot rolled coil simultaneously meets the requirements of high
toughness and
hydrogen sulphide
corrosion resistance of X70 pipeline steel.