Method for producing 45# large flat steel ingot by electric furnace

Abstract

The invention discloses a method for producing 45# large flat steel ingot through an electric furnace, and the flat steel ingot has the weight of 30 to 50 tons. The method comprises the steps of EAF furnace primary smelting furnace steel and iron material batching, tapping conditions, tapping material adding control, LF furnace refining recarburization and slagging deoxidation inclusion removal, vacuum treatment and die casting pouring temperature control. The method concretely comprises the steps of EAF furnace primary smelting furnace steel and iron material batching molten iron control, thecontrol of the carbon content of the molten steel during tapping, the use of carburant in LF furnace refining and the adding of a proper amount of slag and a deoxidizing agent, the forming of white slag and the keeping for enough time, the control of vacuum holding time and argon flow in different stages in VD furnace vacuum treatment, and the control of temperature in die casting pouring. According to the 45# steel produced through the method, the usage amount of the deoxidizing agent is small, inclusions in the steel are few, the thickness of a rolled steel plate ranges from 200 mm to 500 mm, the flaw detection percent of pass reaches 98.4% or above, and benefits are remarkable.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and in particular relates to a method for producing 45# steel large-scale flat steel ingots with a weight of 30 to 50 tons in an electric furnace. Background technique [0002] 45# is a high-quality carbon structural steel, which is widely used in mechanical manufacturing, and its composition is simple, but the thicker 45# wide-thick steel plate is one of the steels that are most likely to fail in flaw detection, especially for steel plates with a rolling thickness of 200mm to 500mm. The pass rate is lower. Rolling a steel plate of this thickness requires the use of large steel ingots, which places high demands on the production of steel ingots. The C content of 45# is relatively high, and the C element reaches 0.45%, which causes a large difference between the liquidus line and the solidus line, and the solidification time of the steel ingot is longer; in addition, the thickness of the large...

AI Technical Summary

Problems solved by technology

[0002] 45# is a high-quality carbon structural steel, which is widely used in mechanical manufacturing, and its composition is simple, but the thicker 45# wide-thick steel plate is one of the steels that are most likely to fail in flaw detection, especially for steel plates with a rolling thickness of 200mm to 500mm. Lower pass rate

The C content of 45# is relatively high, and the C element reaches 0.45%, which causes a large difference between the liquidus line and the solidus line, and the solidification time of the steel ingot is longer; in addition, the thickness of the large steel ingot with a weight of 30-50t is large, which increases the ingot. The solidification time causes serious segregation of gas and inclusions; and the compression ratio of the steel plate rolled from 250mm to 500mm is small, and less gas or inclusion defects may cause the steel plate to fail the flaw detection. The pass rate of the wide and thick steel plate rolled in the past is only 80%~92%