High-strength/toughness X90 hot-rolled steel strip for spiral submerged arc welded pipes and production method thereof

Abstract

The invention relates to a high-strength/toughness X90 hot-rolled steel strip for spiral submerged arc welded pipes, which is composed of the following components in percentage by weight: 0.03-0.06% of C, 0.25-0.35% of Si, 1.80-2.10% of Mn, at most 0.012% of P, at most 0.002% of S, 0.10-0.25% of Cr, 0.15-0.35% of Mo, 0.06-0.11% of Nb, 0.009-0.02% of Ti and at most 0.003% of N. CEpcm(%)=C+Si/30+(Cr+Mn+Cu)/20+Mo/15+V/10+Ni/60+5B<=0.2%. The production method comprises the following steps: smelting, and carrying out continuous casting to obtain a blank; heating the casting blank; carrying out hot rolling; carrying out laminar cooling; and coiling. When the included angle between the steel strip test sample direction and the rolling direction is 30 degrees, Rp0.2 is 630-720 MPa, Rm is greater than or equal to 730 MPa, Rp0.2/Rm is less than or equal to 0.90, the elongation percentage A is greater than or equal to 18%, Agt is greater than or equal to 6%, the -15 DEG C DWTT cross-section shearing rate SA is greater than or equal to 95%, HV10 is less than or equal to 265, the ballistic work single value at -20 DEG C is greater than or equal to 285J, and the ballistic work average value at -20 DEG C is greater than or equal to 355J, thereby completely satisfying the requirements of long distance and high efficacy for the spiral submerged arc welded pipe.

Description

technical field [0001] The invention relates to a hot-rolled steel strip for pipelines and a production method, in particular to a high-strength and toughness X90 hot-rolled steel strip for spiral submerged arc welded pipes and a production method. Background technique [0002] With the rapid development of my country's economy, the demand and dependence of the national economy on oil, natural gas and other energy sources are increasing day by day. In view of the unbalanced distribution of natural gas resources and market demand in my country, large-capacity long-distance pipeline transportation has become an important choice for natural gas transportation in my country. [0003] High-strength steel grades, large wall thickness, and high pressure will become an inevitable trend in the future to realize long-distance and efficient pipeline transportation of natural gas. Under the premise of the same pipeline design indicators such as pipe diameter and pipeline pressure, incr...

AI Technical Summary

Problems solved by technology

[0006] The present invention aims at the deficiencies that the prior art cannot be used to prepare high-strength and toughness spiral submerged arc welded pipes, and provides a method with a yield strength R p0.2 At 630~720MPa, the tensile strength R m ≥730MPa, yield ratio R p0.2 / R m ≤0.90, elongation A≥18%, maximum force elongation Agt≥6%, -20℃ impact energy KV 2 ≥300J, -15℃ DWTT section shear rate SA≥95%, hardness value HV 10 ≤265, high-strength and toughness X90 hot-rolled steel for spiral submerged arc welded pipe with a single value of impact energy at -20°C ≥285J, and an average impact energy value of ≥355J, and its production method

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