Steel for nuclear-island seamless steel tube and production method thereof

Abstract

The invention belongs to the field of metallurgical technology, especially relating to steel for a nuclear-island seamless steel tube and a production method thereof. The steel in the invention comprises the following chemical components in percentage by weight: more than 0 and no more than 0.20 percent of C, no less than 0.10 and no more than 0.35 percent of Si, no less than 0.80 and no more than 1.60 percent of Mn, more than 0 and no more than 0.020 percent of P, more than 0 and no more than 0.015 percent of S, more than 0 and no more than 0.25 percent of Cr, more than 0 and no more than 0.50 percent of Ni, more than 0 and no more than 0.18 percent of Cu, more than 0 and no more than 0.10 percent of Mo, more than 0 and no more than 0.06 percent of V, no less than 0.020 and no more than 0.050 percent of Al, more than 0 and no more than 0.030 percent of Sn and the balance of Fe. The steel in the invention has the advantages of meeting the condition that the carbon equivalent is no more than 0.48 (Ceq = C + Mn / 6 + (Cr + Mo + V) / 5 + [(Ni +Cu)+ 15]<=0.48), controlling the contents of the main elements such as carbon and manganese in the steel, stabilizing the tensile property of the steel tube subjected to simulated destressing heat treatment, and simultaneously ensuring the tensile properties of the tube body and a sample subjected to the simulated destressing heat treatment to meet the technical standards. Because a residual element nickel as an alloy element is added, the low-temperature impact toughness of the steel in the invention is improved, and the impact toughness requirements for the steel at the temperatures of 0 DEG C and minus 20 DEG C are met.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, in particular to steel for nuclear island seamless steel tubes and a production method thereof. Background technique [0002] With the development of my country's nuclear power industry, the construction of nuclear power plants is on the rise, and the nuclear power steel materials used in my country's nuclear power plants basically rely on imports. It has become an important strategic step for the development of my country's nuclear power industry to develop domestic steel materials that meet the requirements of nuclear power plant construction as soon as possible. Due to the harsh environment of nuclear island seamless steel pipes used in nuclear power plants, the mechanical properties of the pipes are required to meet the normal temperature performance test, high temperature performance, (0°C, -20°C) low temperature impact performance, and the performance of the sample after heat treatment an...

AI Technical Summary

Problems solved by technology

The selected raw materials are high-quality steel scrap, forging scrap, and pig iron in a ratio of 5:3:2. However, the harmful elements in the raw material scrap, such as As, Sn, Pb, and Sb, are high in content and difficult to remove during the smelting process.

The molten steel of cast steel ingots is easily polluted by the refractory materials of the central column tube and soup brick, forming large non-metallic inclusions, and the cooling of the steel ingot is naturally cooled by air, and the solidification of the molten steel is gradually carried out from the outside of the steel ingot to the inside. According to Based on the principle of liquid steel separation and crystallization, the inclusions with low melting point are finally solidified, so that a large number of non-metallic inclusions in the steel gather in the middle and upper parts of the ingot, which greatly reduces the purity of the steel.

[0004] To sum up, the material of the main steam pipe of the nuclear island has high requirements on steel purity and performance stability. At present, domestic materials cannot meet such standards, so they cannot be widely used in the nuclear island field of nuclear power plants.

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