Production method of large steel ingot

Abstract

The invention discloses a large-sized steel ingot production method which is simple in technology and low in cost, can achieve welding of a plurality of small-sized electroslag remelting steel ingots and obtain a large-sized electroslag remelting steel ingot. The large-sized steel ingot production method comprises the following steps of firstly preparing the small-sized electroslag remelting steel ingots, then determining one end surfaces of the steel ingots are welding surfaces and processing and protecting the welding surfaces; stacking the two small-sized electroslag remelting steel ingots to be heated under high temperature; upsetting the combined steel ingots according to a certain forging ratio and maintaining pressure of the combined steel ingots after heating; returning to a heating furnace to heat under high temperature and preserving the temperature after upsetting; finally obtaining the large-sized steel ingot. According to the large-sized steel ingot production method, welding of the plurality of small-sized electroslag remelting steel ingots is achieved, the large-sized electroslag remelting steel ingot with pure metal, few occluded foreign substances, compact tissues and a smooth surface is obtained, the quality of a large-sized forge piece is improved, the rejection rate is reduced, the technology is simple, and costs are low.

Description

technical field [0001] The invention relates to the field of manufacturing large steel ingots, in particular to a production method for large steel ingots. Background technique [0002] It is known that large forgings are important parts of major technical equipment, and most of them are key parts of mechanical equipment, such as generator rotors, water turbine main shafts, nuclear power pressure vessels, and large rolling mill rolls. Large-scale forgings have the characteristics of high technical content, long processing cycle, and strict quality requirements. They are generally made of special steel and non-ferrous alloy materials through complex processes. The production of high-quality large forgings requires the use of high-quality large steel ingots, but there are a large number of casting defects in large steel ingots produced by traditional methods, such as porosity, segregation, inclusions, etc., and the segregation of steel ingots becomes more serious as the weight...

AI Technical Summary

Problems solved by technology

[0007] 1) When the steel ingot is large, the cross-sectional area of ​​the electroslag remelting furnace crystallizer will inevitably increase, resulting in a very poor water cooling effect of the water-cooled crystallizer on the center of the steel ingot, weakened control sequence solidification, and shrinkage cavity and looseness in the center very difficult to control

[0008] 2) During the remelting process of large steel ingots, electrodes need to be replaced many times, and electrode replacement will cause process fluctuations, so the stability of the final steel ingot quality is poor

[0009] 3) The electrical power of large electroslag remelting steel ingots is greatly increased, and the electrical efficiency is reduced

[0010] 4) The production time of electroslag remelting steel ingot increases with the increase of ingot, resulting in the extension of production time, generally up to 70 hours or more. During such a long remelting process, the deoxidation system reduces the influence of moisture in the air, It is very difficult to develop high-stable slag components to ensure the stability of electroslag; the remelting time of large ingots is as long as several days and nights, and it is difficult to control the change process of slag components and the composition of molten pool

[0011] 5) The contact interface between gas and slag in the remelting of large ingots is as large as several square meters, and the control of hydrogen becomes extremely complicated when remelting in the atmosphere for a long time

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