A kind of less than 300mpa pipeline steel and its production method

Abstract

The invention relates to pipeline steel smaller than 300MPa and a production method thereof. The production method comprises the following steps of: (1), rolling steel billet for 5-6 passes at the first stage in a recrystallization zone with a rolling temperature of 1000 DEG C-1100 DEG C, wherein the deformation at each pass is bigger than 20%; (2), enabling to-be-heated thickness to be 2-5 times of the finished product thickness; (3), rolling for 5-10 passes at the second stage with the rolling temperature not higher than 1030 DEG C, wherein the accumulated deformation is bigger than 50% and the final-rolling temperature is controlled to 780 DEG C-850 DEG C; and (4), uniformly cooling laminar flow after the rolling, wherein the coiling temperature is 530 DEG C-570 DEG C, and the cooling speed is 10 DEG C / second-20 DEG C / second. The production method of the pipeline steel smaller than 300MPa has the advantages that a few micro alloy elements Ti are added and low-cost steel billet is used to roll out the pipeline steel with strength, toughness and plasticity satisfying the 245MPa level by virtue of a controlled rolling and controlled cooling production technology, so that not only can the production cost of the high-strength hot-rolling structural steel be lowered and the continuous casting number be increased, but also the production pace can be improved.

Description

technical field [0001] The invention relates to a pipeline steel less than 300MPa and a production method thereof, in particular to a method for producing low-grade pipeline steel with a thickness specification of 4-12.7mm and a yield strength not greater than 300Mpa. Background technique [0002] At present, large steel mills at home and abroad mostly use low-C and high-Mn components (C: ≤0.10%; Mn: ≥1.0%) to design and produce low-grade pipeline steel. That is, it is produced by thermomechanical rolling process, and the process performance is stable. But there are still following problems: [0003] 1) Due to the use of Mn alloy to improve product strength, the alloy cost is relatively high; [0004] 2) The tensile strength Rm margin is small (20-40MPa); [0005] 3) There are few types of continuous pouring steel, and small batch contracts cannot be ordered. [0006] With the rising cost pressure and the increasing number of small orders (need to increase continuous cas...

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Problems solved by technology

[0005] 3) There are few types of continuous pouring steel, and small batch contracts cannot be ordered

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