High-strength pipe steel and method for manufacturing same

Abstract

The invention relates to a method for manufacturing pipe steel. The pipe steel comprises the following components in percentage by weight: 0.02-0.12 percent of C, 0.10-0.35 percent of Si, 1.40-2.00 percent of Mn, no more than 0.015 percent of P, no more than 0. 005 percent of S, 0.021-0.05 percent of Ti, 0.05-0.40 percent of Cr, 0.05-0.30 percent of Mo, 0.10-0.30 percent of Cu, 0.10-0.24 percent of Ni, no more than 0. 008 percent of N, 0.02-0.07 percent of Nb, 0.01-0.08 percent of V and the balance of Fe and inevitable impurities. The method comprises the steps of smelting, external refining, casting, slab reheating, controlled rolling, controlled cooling, quenching and tempering in a converter or an electric furnace. The reheating temperature of the slab is 1100-1250 DEG C. The controlled rolling comprises a recrystallization zone rolling step and a non-recrystallization zone rolling step. The quenching and tempering comprises a quenching step and a tempering step. The pipe steel has the characteristics of high strength, excellent low temperature impact toughness and excellent weldability, and can be used for constructing long-distance petroleum and natural gas transmission pipelines, slurry transmission pipeline, city pipeline networks and the like.

Description

technical field [0001] The invention belongs to the field of low-alloy steel manufacturing, and in particular relates to a steel for thick-gauge high-strength pipe fittings and a manufacturing method thereof. Background technique [0002] Pipe fittings are used to change the direction of the pipeline, change the size of the pipe diameter, branch the pipeline, and locally strengthen it to achieve special connections. It is widely used in various pressure pipelines, such as oil and gas transmission pipelines, urban pipe network pipes, thermal Pipes, slurry pipes, etc. Commonly used pipe fittings include elbows, tees, reducers (big and small heads), pipe caps, pipe joints, pipe collars, nozzles, etc. [0003] Pipe fittings are generally made by steel plate forming, heat treatment, or by direct forging. Pipe fittings are connected to straight pipe sections or valves by welding, and the delivery pressure must be basically the same as that of straight pipe sections. Therefore, t...

AI Technical Summary

Problems solved by technology

However, the steel pipe produced by the invention still has a high C content, which is unfavorable to the welding performance

[0006] It can be seen that similar products in the prior art cannot fully meet the current use and manufacturing requirements, and it is necessary to develop a high-strength and high-toughness steel for pipe fittings

Images