Low-yield-ratio thin-gauge high-strength and acid-resistant pipeline steel hot rolled coil plate and manufacturing method thereof

Abstract

The invention provides a low-yield-ratio thin-gauge high-strength and acid-resistant pipeline steel hot rolled coil plate. The hot rolled coil plate comprises the chemical components, by mass, of 0.04%-0. 065% of C, 0.15%-0.30% of Si, 0.8%-1.15% of Mn, 0.012% of P or the less, 0.0015% of S or the less, 0.006% of N or the less, 0.025%-0.04% of Nb, 0.010%-0.025% of Ti, 0.1%-0.3% of Cr, 0.02%-0.05% of Als and the balance Fe and inevitable impurities. Through combination control over the components and the technique, the high strength, low yield ratio, excellent HIC resistance and excellent SSCC resistance of thin-gauge high-strength and acid-resistant pipeline steel can be achieved, the cost is lower, strength is higher, the thinner gauge can be achieved, control over the smelting and rolling processes is relatively simple, the production efficiency is greatly improved, and control over the process cost is greatly strengthened.

Description

technical field [0001] The invention relates to the field of pipeline steel manufacturing, in particular to a hot-rolled coil of low-yield-ratio thin-gauge high-strength acid-resistant pipeline steel and a manufacturing method thereof. Background technique [0002] At present, the world's dependence on energy is still mainly oil and natural gas. However, with the gradual depletion of easy-to-exploit "sweet gas", rich H 2 The "sour gas" exploitation of S gas is gradually increasing. Due to the high content of C, Mn, P, S and other elements in conventional pipeline steel, hydrogen atom aggregation defects such as banded structure, MA and strip-shaped MnS are easily formed in the finished pipeline steel structure, resulting in hydrogen-induced cracking. Although the acid-resistant pipeline steel can effectively avoid the above-mentioned defects, the yield ratio of the finished steel plate is greatly increased due to the adoption of a low-C and low-Mn composition system, especi...

AI Technical Summary

Problems solved by technology

Due to the high content of C, Mn, P, S and other elements in conventional pipeline steel, it is easy to form banded structure, MA and strip-shaped MnS and other hydrogen atom aggregation defects in the finished pipeline steel structure, resulting in hydrogen-induced cracking

Although the acid-resistant pipeline steel can effectively avoid the above-mentioned defects, the yield ratio of the finished steel plate is greatly increased due to the adoption of a low-C and low-Mn composition system, especially for thin-gauge acid-resistant pipeline steel. more difficult

Although the strength of the steel plate can be improved by adding Cu, Cr, Ni, and Mo alloy elements, the yield and tensile strength increase at the same time, and the yield ratio is still difficult to control at a low level. At the same time, the cost is greatly increased, and the economy is not good.

[0003] In the prior art, the Chinese patent document with the publication number CN104099522A discloses a "copper-nickel-free acid-resistant pipeline steel X52MS and its manufacturing method for hot-rolled coils", the chemical composition of which is mainly C: 0.02-0.06wt %, Si:0.05~0.35wt%, Mn:1.0~1.4wt%, P≤0.018wt%, S≤0.003wt%, Cr:0.10~0.50wt%, Ti:0.005~0.10wt%, Nb:0.005~ 0.10wt%, V: 0-0.05wt%, and the preferred C content in the finished steel plate is 0.035%, which requires that the carbon content should not exceed 0.02% when the converter is tapped. If the requirement is too high, it will seriously damage the converter and reduce the temperature of the furnace. age

At the same time, the thinnest finished steel plate in the embodiment is only 9.4mm, and the yield strength ratio reaches 0.91, and the products with thinner specifications cannot meet the technical requirements

[0004] Another Chinese patent document with the publication number CN102851590A discloses "an acid-resistant low-manganese X70 pipeline steel and its production method". ~1.25%, P: 0~0.019%, S: 0~0.006%, Nb: 0.06~0.09%, Ti: 0.010~0.020%, Mo: 0.20~0.30%, Ni: 0.05~0.30%, Cu: 0.05~ 0.30%, Als: 0.015-0.040%, although the yield ratio of the 8mm steel plate is as low as 0.84, the addition of Cu, Ni, and Mo in this specification reaches 0.20-0.25% at the same time, and the alloy cost is too high

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