X80 hot-rolled steel plate for hot bending elbow parent pipe and manufacturing method thereof

Abstract

The invention provides an X80 hot-rolled steel plate for a hot bending elbow parent pipe. The X80 hot-rolled steel plate comprises the following components of, in percentage by mass, 0.07-0.11% of C,0.10-0.45% of Si, 1.65-1.85% of Mn, 0.020-0.060% of Al, 0.025-0.075% of Nb, 0.010-0.025% of Ti, 0.03-0.06% of V, less than or equal to 0.45% of Cr, less than or equal to 0.35% of Cu, 0.15- 0.45% of Ni, 0.15% -0.40% of Mo, less than or equal to 0.015% of P, less than or equal to 0.005% of S, less than or equal to 0. 0060% of N, less than or equal to 0.0005% of B, and the balance Fe and inevitable impurity elements. The yield strength (Rt0.5)of the obtained X80 hot-rolled steel plate for the hot bending elbow parent pipe is larger than or equal to 580 MPa, the tensile strength (Rm) is larger than or equal to 650 MPa, the yield ratio (Rt0.5/Rm) is less than or equal to 0.90%, the elongation (A) is larger than or equal to 30%, the Sharpy impact energy at minus 30 DEG C is larger than or equalto 220 J, the Sharpy impact energy at minus 60 DEG C is greater than or equal to 200 J, and the hardness is less than or equal to 265 HV10.

Description

technical field [0001] The present application relates to the technical field of pipeline steel rolling, in particular, to an X80 hot-rolled steel plate for hot-simmering and bending parent pipes and a manufacturing method thereof. Background technique [0002] Energy is an important basis for the sustainable development of the national economy. Natural gas is a low-carbon mineral energy. Expanding its proportion in my country's energy structure has important practical significance for ensuring my country's energy and protecting the ecological environment. Major iron and steel enterprises are increasingly Pay more and more attention to the research and development and production of pipeline steel. [0003] X80 hot-rolled coils for pipelines are high-strength pipeline steels developed to meet the requirements of pipeline steels for high pressure resistance and large diameters. X80 hot-rolled coils with a thickness specification of 18.4mm to 22mm are in great demand in the mark...

AI Technical Summary

Problems solved by technology

[0004] The pipe-making process of bent pipe is generally online electromagnetic induction heating bending, water spray quenching, and offline tempering. The formability, weldability and performance of the parent pipe when the pipe is made should also focus on the microstructure evolution and mechanical properties of the steel pipe during hot bending and tempering heat treatment, requiring appropriate alloy content, Nb, V, Mo , Ni and other precious alloys and carbon equivalents have upper and lower limit requirements to improve the heat treatment performance of steel and ensure that the strength and low temperature toughness meet the requirements of pipeline standards; The controlled rolling and controlled cooling process has prominent contradictions in the control of strength and toughness. Some steel plates are tempered to match the strength and toughness after rolling, resulting in waste of cost

Compared with the chemical composition of the existing X80 grade hot-rolled steel plate for hot-simmering and bending parent pipe, the addition of precious metal elements is too sufficient, and the effect of quenching and tempering heat treatment after steel plate making is not fully utilized to reduce the cost of steel plate manufacturing, such as CN102268612B, CN102011064B, and CN108239720A patents The Ni content in the medium is more than 0.50%, and some Cu, Nb, and V contents are not low, and the cost of the alloy is high

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