Low-yield-ratio high-strength pipeline steel production method

Abstract

The invention relates to a low-yield-ratio high-strength pipeline steel production method. The method includes the working processes of steelmaking-continuous casting, casting blank heating, casting blank control rolling, steel plate control cooling and straightening through a straightening machine; in the working process of rolling, during austenite crystalline region elongation rolling, the single track reduction rate is not lower than 16%, the accumulated valid reduction rate is not lower than 70%, and the austenite crystalline region single track reduction rate is not higher than 18%; and in the working process of control cooling, the austenite crystalline region rolling starting temperature is lower than Ar3 temperature by 20 DEG C to 30 DEG C, the rolling temperature scope is located in an austenite and ferrite coexistence region, the cooling starting temperature is lower than the Ar1 temperature, and large phase change stress is prevented from being generated in the cooling process. A pipeline steel product produced through the process has the high strength, and meanwhile has the good tenacity and the excellent yield ratio scope; and the contradiction of high strength and low yield ratio of the iron and steel industry pipeline steel series products is solved, and the best level of similar enterprises in China is achieved.

Description

technical field

[0001] The invention relates to a production method of high-strength pipeline steel with low yield ratio, belonging to the technical field of metal rolling. Background technique

[0002] As a raw material for pipelines transporting oil and natural gas, pipeline steel is of paramount importance to safety, and the yield ratio is a measure of the deformation ability of the material from initial plastic deformation to final fracture, so the yield ratio is an important mechanical performance index in pipeline steel. The smaller the yield ratio, the greater the deformation capacity of the material and the greater the strength margin; the larger the yield ratio, the smaller the plastic range of the material after yielding, and the easier it is to fracture. Before the steel pipe undergoes internal pressure deformation to rupture, there is a limit value for the circumferential deformation, which decreases as the yield ratio of the steel pipe increases. Therefore, for...

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