Production method of low-cost continuous casting round billet for ultra-supercritical high-pressure boiler tube

Abstract

The invention belongs to the technical field of metallurgy and mainly relates to a production method of a low-cost continuous casting round billet for an ultra-supercritical high-pressure boiler tube.The production method comprises the following steps: primarily smelting molten steel in an electric arc furnace, wherein the phosphorus content and the harmful element content of the molten steel arelow; melting chromium iron, molybdenum iron, tungsten iron and other alloys in an intermediate frequency furnace; after the steel tapping operation in an electric furnace, collecting molten alloy steel from the intermediate frequency furnace, injecting the molten alloy steel into an argon oxygen furnace, and performing the decarburization operation, the desulfurization operation and the oxygen nitridation operation, wherein the top-bottom composite smelting mode is adopted for the argon oxygen furnace; and after the steel tapping operation in the argon oxygen furnace, performing fine alloy adjustment in a ladle refining furnace, performing vacuum degassing in a VD furnace, casting the continuous casting round billet on a vertical continuous casting machine after the vacuum degassing operation in the VD furnace, wherein the inner diameter of the continuous casting round billet reaches 400-800 mm. The continuous casting round billet produced according to the production method provided by the invention is low in production cost, high in composition uniformity and high in macroscopic quality; and the quality and the market competitiveness of an ultra-supercritical high-pressure boilertube billet can be improved.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and in particular relates to a production method for continuous casting round blanks of low-cost ultra-supercritical high-pressure boiler tubes. Background technique [0002] With the rapid development of my country's economy and the continuous improvement of people's living standards, the demand for electricity has increased rapidly, and at the same time, the emphasis on environmental protection issues has also increased. The main development trend of thermal power generation is: to focus on the development of high-efficiency, low-pollution, low-energy consumption, low-cost power generation equipment and new clean coal combustion power generation technology, so large-capacity, high-parameter supercritical and ultra-supercritical generators are composed of The leading trend of thermal power development. The increase of unit operating parameters (temperature, pressure) and unit capacity has pr...

AI Technical Summary

Problems solved by technology

[0003] At present, 10Cr9MoW2VNbBN steel for ultra-supercritical high-pressure boiler tubes in the industry is mostly produced by die-casting steel ingots after pressure processing, and the smelting method is mostly electric arc furnace smelting + ladle refining furnace refining + VD or RH furnace vacuum degassing, which adjusts Cr components. The alloy is low-carbon or micro-carbon ferrochrome, nitrogen alloy is used to adjust the N composition, and ferro-tungsten is added in the ladle refining furnace. Nitrogen is adjusted after gas, on the one hand, the cost of the alloy is high, and on the other hand, the alloy is added after vacuum treatment, which is easy to absorb gas and pollute the molten steel. In addition, the melting point of tungsten and iron is high and the density is high, and the composition uniformity is poor after adding in the ladle refining furnace.

This smelting method has high production costs, poor composition uniformity, and low purity of molten steel

[0004] The existing 10Cr9MoW2VNbBN steel for ultra-supercritical high-pressure boiler tubes is mostly produced by die-casting steel ingots after pressure processing. During die-casting production, even if good protective pouring methods are used, the contact between the nozzle steel flow and the atmosphere will inevitably cause secondary oxidation. The refractory materials of the middle injection pipe and the soup channel system will also pollute the high-purity molten steel refined outside the furnace, and the yield rate of die casting production is low, the production efficiency is low, and the production cost is high

[0005] With the development of continuous casting technology and the intensification of market competition, it will become a trend to produce ultra-supercritical high-pressure boiler tube blanks by continuous casting. There are serious central cracks and chemical composition differences between the inner and outer arc sides of the slab. In order to eliminate such quality defects, downstream users can only use methods such as central drilling to reduce the yield rate, and the production cost is relatively high.