A kind of high plasticity thick gauge pipeline steel plate and its manufacturing method

Abstract

A high plasticity and thick specification pipeline steel and a manufacturing method thereof, the weight percentages of which are: C 0.03-0.10%, Si 0.1-0.5%, Mn 1.51-1.85%, P≤0.015%, S≤0.002%, Cr 0.05- 0.3%, Mo 0.05~0.20%, Cu0.06~0.3%, Ni 0.17~0.50%, Nb 0.05~0.10%, Ti 0.005~0.02%, Ca 0.001~0.005%, Al 0.02~0.045%, N≤0.006% , B≤0.0002%, O≤0.005%, remaining Fe and inevitable inclusions; and, 0.06≤J c×Mn ≤0.14, carbon manganese product parameter J C×Mn =C*Mn*10 4 . The high-plasticity thick specification pipeline steel has a yield strength of 450-635 MPa, a tensile strength of 520-780 MPa, a low-temperature impact energy at -20°C higher than 275J, a full-wall thickness DWTT shear fracture area percentage at -20°C greater than 85%, and a uniform elongation. More than 8%, it can be used for the construction of submarine pipelines, crossing pipelines and polar pipelines, mainly for long-distance transportation of natural gas.

Description

technical field [0001] The invention relates to pipeline steel, in particular to a high-plasticity thick-specification pipeline steel and a manufacturing method thereof. Background technique [0002] With the increasing demand for energy such as oil and natural gas in the global consumer market, the pipeline transportation of oil and natural gas tends to develop from land to ocean and from small to large transportation, which puts forward high requirements for pipeline safety. The construction of submarine pipelines is usually carried out in the J-type or S-type way. During the service process, it is necessary to cross ravines and overcome harsh environments such as fluid movement. Therefore, in addition to high strength and high toughness, submarine pipelines are often required to be thick and thick. Wall pipes to improve structural stability, while requiring high plastic deformation capacity to ensure service safety. [0003] Judging from the existing literature research,...

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Problems solved by technology

The representative process directions include the ferrite + lower bainite duplex structure obtained by the hesitation + controlled cooling process adopted by Chinese companies, and the MA component + bainite duplex structure obtained by the online heat treatment HOP process adopted by JFE in Japan , these two microstructure types can obtain high uniform elongation, but due to the existence of the dual-phase interface, the low-temperature impact toughness of the steel is significantly reduced, which is not conducive to the safety of the crack arrest of the steel

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