Cr-containing thick-wall pipeline steel and coiled sheet controlled rolling and controlled cooling method thereof

Abstract

The invention provides a Cr-containing thick-wall pipeline steel which includes chemical components with the following weight percentage (%): 0.54 to 0.90 of Cr, 0.03 to 0.09 of C, 0.24 to 0.35 of Si,1.23 to 1.30 of Mn, less than or equal to 0.015 of P, less than or equal to 0.005 of S, less than or equal to 0.0045 of N, 0.018 to 0.030 of Ti, 0.046 to 0.08 of Nb, 0.23 to 0.30 of Cu, 0.10 to 0.40 of Ni, 0.015 to 0.060 of AIs, and the balance of iron and residual elements. A coiled sheet controlled rolling and controlled cooling method is realized by that: the heating temperature of billet steelis 1150 to 1175 DEG C, the rough rolling start temperature is 1130 to 1155 DEG C, the finish rolling start temperature is 1020 to 1030 DEG C, the final rolling temperature is 800 to 850 DEG C, the coiling temperature is 450 to 540 DEG C, the total pressing rate is not less than 85 percent, and the cooling speed is controlled to be 15 to 20 DEG C per second.

Description

technical field [0001] The invention belongs to the field of pipeline steel, and in particular relates to a thick-walled pipeline steel and a coil controlled rolling and controlled cooling method thereof. Background technique [0002] The oil and gas industry is the main energy source for industrial development. Oil and gas pipeline transportation has the characteristics of high efficiency, safety, and economy, and is the main form of long-distance oil and gas transportation. With the gradual changes in the international energy structure, the proportion of natural gas in energy will increase dramatically in the next few decades. Natural gas transmission pipelines tend to develop in the direction of large diameter, high pressure and thick wall. The service conditions of pipelines are becoming more and more harsh, such as the increase of conveying pressure, the conveying medium is complex, and many pipelines need to pass through severe cold regions, swamps, deserts or densely...

AI Technical Summary

Problems solved by technology

[0004] The technical problem to be solved by the present invention is to provide a thick-walled pipeline steel with strong tear resistance in the range of 20-25.4mm and its plate coil controlled rolling and controlled cooling method, by adding Cr to ensure the toughness and fine grain requirements at the same time Appropriately increase the wall thickness to solve the problem of insufficient safety of oil and gas pipelines caused by insufficient wall thickness due to certain strength and toughness. use needs