A kind of steel for 620mpa level nuclear first-level equipment and its manufacturing method

Abstract

The invention provides a steel for 620 MPa level nuclear first grade equipment and a manufacturing method thereof. The steel is composed of the following components in percentage by weight: 0.14% to 0.25% of C, 0.15% to 0.40% of Si, 1.15% to 1.60% of Mn, not more than 0.015% of P, not more than 0.010% of S, 0.40% to 0.70% of Ni, 0.45% to 0.60% of Mo, 0.05% to 0.30% of Cr, 0.020% to 0.050% of Alt, 0.002% to 0.03% of V, 0.002% to 0.03% of Ti, and the balance being Fe. The manufacturing method comprises the following steps: (1) smelting: subjecting the steel plates with a thickness less than or equal to 80 mm to a continuous casting treatment in a converter or to a mould casting treatment in an electric furnace, subjecting the steel plates with a thickness more than 80 mm to a mould casting treatment in an electric furnace, adopting an external refining and vacuum degassing treatment; (2) rolling: subjecting the continuous casting slabs to a two-sectional rolling treatment, wherein the heating temperature is higher than or equal to 1150 DEG C, the finish rolling temperature in the recrystallization area is higher than or equal to 1000 DEG C, the finish rolling temperature in the non-recrystallization area is 830 DEG C to 870 DEG C, the accumulated deformation is more than or equal to 50%, and the heating temperature of the mould casting steel ingots is higher than or equal to 1150 DEG C; (3) hardening and tempering: controlling the quenching temperature in a range of 880 DEG C to 900 DEG C, maintaining the temperature for 2-3 min / mm; controlling the tempering temperature in a range of 630 DEG C to 650 DEG C, and maintaining the temperature for 2-4 min / mm. Each performance index of the steel plate prepared by the manufacturing method can meet the requirements of the nuclear first grade equipment.

Description

technical field [0001] The invention belongs to the technical field of ferrous metal materials, and in particular relates to a steel for nuclear primary equipment and a manufacturing method thereof. Background technique [0002] With the rapid economic development of all countries in the world, nuclear energy, as a clean, safe and stable energy source, has been paid more and more attention by all countries. It has become a trend to use nuclear energy safely and vigorously develop nuclear power. In addition, great progress has been made in the application of nuclear power technology. It has developed from the original "second generation" technology to the current "second generation plus", "third generation" and "fourth generation" technologies, which has made greater safety performance improve. [0003] Among the many nuclear power units built with different nuclear power technologies, the steel used for nuclear first-level equipment is used as the shell material of key equi...

AI Technical Summary

Problems solved by technology

[0008] From the perspective of the three processes, the strength of the steel plate after quenching and tempering treatment fully meets the index requirements, and has a large margin, and the performance of the 1 / 4 and 1 / 2 of the plate thickness is basically the same; The strength drops significantly, especially the tensile strength of 1 / 2 is only slightly higher than the index requirement; under the high temperature condition of 350 ℃, the yield strength of the steel plate can still meet the index requirement, but the tensile strength drops significantly, especially at 1 / 2 The performance can no longer meet the needs of the construction of nuclear first-class equipment

Images