A kind of X70 pipeline steel with high HIC performance and its preparation method

Abstract

The invention relates to X70-grade pipeline steel with high HIC (hydrogen induced cracking) resistance as well as a preparation method thereof. The chemical components of the pipeline steel are as follows: 0.04 to 0.05 weight percent of C, 0.2 to 0.3 weight percent of Si, 1.1 to 1.2 weight percent of Mn, 0.006 to 0.008 weight percent of P, 0.0008 to 0.0015 weight percent of S, 0.08 to 0.10 weightpercent of Cu, 0.2 to 0.25 weight percent of Cr, 0.09 to 0.10 weight percent of Ni, 0.1 to 0.12 weight percent of Mo, 0.03 to 0.04 weight percent of Nb, 0.02 to 0.03 weight percent of V, 0.002 to 0.005 weight percent of Ti, 0.002 to 0.005 weight percent of Mg and the balance of Fe and unavoidable impurities. The rolling temperature of the pipeline steel is as follows: the temperature of rough-rolling finishing rolling is 950 to 1050 DEG C; the temperature of precision-rolling open rolling is 920 to 950 DEG C; the temperature of precision-rolling finishing rolling is 860 to 890 DEG C; the temperature of relaxation terminating is 730 to 740 DEG C; and the temperature of plate blank re-reddening is 400 to 430 DEG C. The process is simple; and the prepared product has high HIC resistance.

Description

technical field [0001] The invention belongs to the technical field of X70 pipeline steel. In particular, it relates to an X70 grade pipeline steel with high HIC resistance and a preparation method thereof. Background technique [0002] Hydrogen induced cracking (HIC) is one of the main forms of corrosion failure of pipeline steel in acidic environment. Pipeline steel in wet H 2 Hydrogen-induced cracking occurs in the S environment, mainly due to the S 2- and HS - Acts as a poisoning agent, promoting the solution to generate adsorbed hydrogen atoms H on the metal surface ads , adsorbed hydrogen atom H ads Gradually penetrate into the steel to become dissolved hydrogen atoms H abs , dissolved hydrogen atoms H abs Hydrogen traps in steel such as inclusion / matrix interface, band structure, dislocation, grain boundary, etc. gather to form H 2 Hydrogen pressure is generated. As the number of accumulated H atoms increases, when the hydrogen pressure exceeds a certain criti...

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Problems solved by technology

[0006] "Pipeline steel with excellent HIC resistance and pipeline pipe made of the steel" (CN1914341) patent technology discloses a method for improving the HIC resistance of the material by controlling the size of TiN precipitates in the steel. The technology adds Cu and Ni and other elements to prevent the entry of hydrogen atoms, but the addition of Cu elements will cause the segregation of Cu atoms at the grain boundaries, which will adversely affect the HIC resistance of the material