Hardening and tempering type anti-acid pipeline steel and manufacturing method thereof

Abstract

The invention discloses hardening and tempering type anti-acid pipeline steel which is prepared from the chemical elements in percentage by mass: 0.025 to 0.090 percent of C, 0.1 to 0.5 percent of Si,0.50 to 1.35 percent of Mn, less than or equal to 0.020 percent of P, less than or equal to 0.003 percent of S, 0.01 to 0.09 percent of Mo, 0.01 to 0.06 percent of Nb, 0.005 to 0.02 percent of Ti, 0.001 to 0.006 percent of Ca, 0.02 to 0.045 percent of Al, larger than 0 and smaller than or equal to 0.010 percent of N, and the balance Fe and other inevitable impurities. A microstructure of the hardening and tempering type anti-acid pipeline steel has tempered bainite with the phase proportion being larger than 90 percent, and has the grain size reaching to more than 11 grades. In addition, theinvention further discloses a manufacturing method of the hardening and tempering type anti-acid pipeline steel. The hardening and tempering type pipeline steel provided by the invention has the yieldstrength being 290 to 550MPa, the tensile strength being 415 to 760MPa, the charpy impact work at minus 40 DEG C being higher than 120J, and the shear fracture area percentage under a drop-weight tear test (DWTT) at minus 25 DEG C being larger than 85 percent.

Description

technical field [0001] The invention relates to a steel grade and a manufacturing method thereof, in particular to a pipeline steel and a manufacturing method thereof. Background technique [0002] Before the emergence of controlled rolling and controlled cooling technology, industrial production used hot rolling forming + heat treatment to produce pipeline steel plates to meet different mechanical property requirements; controlled rolling and controlled cooling technology can reduce production processes, reduce production costs, and obtain both The strength and toughness of pipeline steel gradually replaced the original production process of post-forming heat treatment. Nevertheless, due to the good composition, uniformity and stability of the heat-treated pipeline steel, some pipeline engineering projects require the use of quenched and tempered pipeline steel pipes in the design, and have become the key products of some special pipeline projects. The difficulty mainly li...

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Problems solved by technology

However, the technical solution disclosed in this patent document uses an excessively high addition of Mn element, and does

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