CN-121976048-A - Stable arcing method in electroslag remelting process

Abstract

The invention relates to the technical field of electroslag remelting, in particular to a stable arcing method in an electroslag remelting process, which sequentially comprises the following steps of a) preparing an arc striking slag agent in a pretreatment stage, uniformly adding the arc striking slag agent into the bottom of a crystallizer, b) pre-arcing, namely applying initial current to keep the distance between the lower end of a consumable electrode and the surface of the arc striking slag agent at 5-10 mm, adding bulk slag into the crystallizer in batches, lifting the consumable electrode at the same time, wherein the surface temperature of a slag pool reaches 1200-1300 ℃, C) stabilizing the arc striking stage, namely stepwise lifting current to 70-80% of rated remelting current, stabilizing the voltage of the slag pool at 80-150V, keeping the arc length at 15-20 mm, d) in a transition stage, lifting current to rated remelting current, micro-stirring, controlling the temperature of the slag pool at 1600-1800 ℃, and converting into a normal electroslag remelting mode when the melting rate is more than or equal to 95%. The invention has stable arcing, small thermal shock, shortened arcing time and improved production efficiency.

Inventors

• LI DEJUN
• ZHAO LIANG
• JIA JIXIANG
• HUANG YUPING
• YANG JI
• LI BOYANG
• WANG HAIWEI
• SUN SHEN

Assignees

• 鞍钢股份有限公司

Dates

Publication Date

20260505

Application Date

20260209

Claims (5)

1. 1. The stable arcing method for the electroslag remelting process is characterized by comprising the following stages in sequence: a) The pretreatment stage comprises the steps of preparing an arc striking slag agent, wherein the arc striking slag agent comprises 2-5% of CaF 2 ：65%～75%、Al 2 O 3 ：20%～30%、Li 2 O by mass percent, and the addition amount of the arc striking slag agent is 5-15% of the total slag amount; uniformly adding an arc striking slag agent into the bottom of a crystallizer, processing the bottom end of a consumable electrode into an arc surface, and controlling the filling ratio of the diameter of the consumable electrode to the inner diameter of the crystallizer to be 70% -85%; b) Applying an initial current which is 30% -50% of rated remelting current, wherein the feeding speed of a consumable electrode is 0.2-0.5 mm/min, so that the distance between the lower end of the consumable electrode and the surface of an arc striking slag agent is kept at 5-10 mm, adding bulk slag into a crystallizer in batches after 10-20 min, lifting the consumable electrode, and keeping the distance between the consumable electrode and the slag surface at 5-10 mm all the time, and continuing 10-15 min after all the bulk slag is added into the crystallizer, so that the surface temperature of a slag pool reaches 1200-1300 ℃; c) The stable arcing stage comprises the steps of step-lifting current to 70-80% of rated remelting current at a rate of 50-80A/min, stabilizing the slag bath voltage to 80-150V through voltage feedback, and adjusting the feeding speed of a consumable electrode to 0.5-1.0 mm/min when the voltage fluctuation exceeds +/-5V so as to maintain the arc length to 15-20 mm; d) And in the transition stage, current is increased to rated remelting current at the speed of 80-100A/min, micro stirring is carried out, the temperature of the slag pool is controlled to 1600-1800 ℃, the melting rate of the slag pool is detected in real time, and the normal electroslag remelting mode is converted when the melting rate is more than or equal to 95%.
2. 2. The stable arcing method for the electroslag remelting process according to claim 1, wherein in the pretreatment stage, the thickness of the arc striking slag agent added into the bottom of a crystallizer is controlled to be 10-30 mm, and the height of the cambered surface of the consumable electrode is controlled to be 5-10 mm.
3. 3. The method for stabilizing and arcing during electroslag remelting according to claim 1, wherein in the pretreatment stage, the arc striking slag is dried before being added into the crystallizer, so that the water content of the slag is reduced to below 0.5%.
4. 4. The stable arcing method for the electroslag remelting process according to claim 1, wherein in the stable arcing stage, the acquisition frequency of the voltage sensor is 1-5 Hz.
5. 5. The stable arcing method for the electroslag remelting process according to claim 1, wherein in the transition stage, micro-stirring is performed by controlling the current fluctuation frequency to be 1-2 Hz.

Description

Stable arcing method in electroslag remelting process Technical Field The invention belongs to the technical field of electroslag remelting, and particularly relates to a stable arcing method in an electroslag remelting process. Background The electroslag remelting technology is a key process for improving the material performance by heating a slag pool through an electric arc and removing impurities and uniform components in steel by utilizing the metallurgical effect of Wen Zhachi. The arcing stage is used as an initial link of electroslag remelting, and the stability of the arcing stage directly determines the quality and production efficiency of subsequent remelting. The existing arcing method has the following defects that the direct arcing method is unreasonable in initial current setting, if the current is too large, local overheating of a slag pool is easy to occur, the service life of a bottom water tank is reduced, if the current is too small, stable electric arcs cannot be formed, frequent arc breaking (the arc breaking rate can reach 15% -20%), the arcing time is long, the production efficiency is affected, slag inclusion and component segregation defects occur in cast ingots, the arcing difficulty is reduced by adding an arcing agent such as carbon powder and iron powder, impurities (such as C, S, P) in the arcing agent can be fused into molten steel, the purity of the molten steel is reduced (the impurity content is increased by 0.003% -0.005%), in addition, the arcing instability also easily causes nitrogen increase in the process, and the production requirements of high-quality alloy materials cannot be met. And the current peak value can be caused by unstable arcing, damage to equipment, especially a bottom water tank, is easy to cause, the service life of the equipment is reduced, and the equipment cost is increased. The existing method mostly adopts fixed current and feed speed, does not combine with real-time parameter adjustment of slag bath temperature, voltage and the like, and when the slag bath components and the ambient temperature change, the arcing stability is obviously reduced. Therefore, there is a need for an electroslag remelting arcing method that combines arcing stability, molten steel purity and parameter adaptability. Patent CN201010599689.6 discloses an electroslag remelting arc striking agent and an arc striking method thereof, and the method is characterized in that the arc striking agent is formed by crushing waste graphite electrodes into particles with the mass of 80-140 g. When arcing, firstly, the arc striking agent is put into an electroslag remelting furnace, the initial voltage is manually adjusted to 25V and gradually increased to 35V, the current is gradually increased from 0 ampere to 5 kiloampere, and the automatic control is carried out after the current is stable. Although the arc striking agent is prepared by the waste graphite electrode, the problems of high cost, titanium-containing pollution and the like of the traditional arc striking agent are solved, but the arc striking agent still has obvious defects from the aspects of technical practicality, suitability and industrialized application. Firstly, the quality control and the carburetion risk balance of the arc striking agent particles are difficult, the particle quality is limited to 80-140 g, and although the condition that the particle quality exceeds 140 g can cause carburetion of molten steel is pointed out, the requirement of different steel types on the difference of carbon content is not considered. Secondly, the arcing process is influenced by various factors, other related factors are not considered, the patent only focuses on the arcing stage, and the influences of parameters such as the filling ratio between the electrode and the crystallizer, the baking slag agent and the like are not related. Disclosure of Invention The invention aims to solve the technical problem of providing a stable arcing method in an electroslag remelting process, which is suitable for electroslag remelting production of high-quality special steel and alloy materials, and can particularly solve the problems of arc interruption, current fluctuation and affected molten steel purity in the arcing stage. In order to achieve the above purpose, the invention adopts the following technical scheme: The stable arcing method in the electroslag remelting process sequentially comprises the following stages: a) The pretreatment stage comprises the steps of preparing an arc striking slag agent, wherein the arc striking slag agent comprises 2-5% of CaF 2：65%～75%、Al2O3：20%～30%、Li2 O by mass percent, and the addition amount of the arc striking slag agent is 5-15% of the total slag amount; uniformly adding an arc striking slag agent into the bottom of a crystallizer, processing the bottom end of a consumable electrode into an arc surface, and controlling the filling ratio of the diameter of the consumable electrode to the inner d