Automatic feeding process for Ni3 type electroslag ingots with specification of phi 1000mm
By adopting the automatic replenishment process in electric slag metallurgical, the voltage and current reduction rate is set in installments, and the heat preservation stage is set to solve the problem of low degree of automation process automation, which significantly improves the quality of the port cap of the electric residue. The depth of the shrinking hole.
Patent Information
- Application Number
- CN202411454926.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-17
- Publication Date
- 2025-01-28
AI Technical Summary
In the existing electroslag metallurgy technology, the degree of automation of the replenishment and shrinkage process is low, which makes it difficult to ensure the quality of the cap end of the electroslag ingot, and is prone to abnormal shrinkage holes, affecting the subsequent forging process and product quality.
The use of an automatic shrinking process is used to set the power parameter to divide the complement process into the first three and then three phases. The voltage and current are reduced at different rates at different stages, and finally entered the thermal insulation stage to achieve automated supplementary shrinkage.
Effectively reduce the depth of the port of the ni3 -type electric slag cap, which improves the quality of the port of the electric slag ingot caps, avoids the impact of human factors, and ensures the stability and high quality of the product.
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of electroslag metallurgy, and relates to an automatic shrinkage compensation process for Ni3 electroslag steel with a specification of Φ1000mm, which can ensure the quality of the Ni3 electroslag ingot cap end. Background Art
[0002] Electroslag remelting is a smelting method for secondary refining of steel billets smelted in electric furnaces or converters. Its main working principle is to pass a large current through the steel billet, and the slag produced by the liquid slag pool gradually melts the steel billet. When the molten metal droplets pass through the liquid slag pool, most of the impurities in them are absorbed by the slag pool, and finally they are cooled and solidified by the water-cooled crystallizer to form high-quality electroslag ingots.
[0003] With the development of electroslag remelting technology, the automation level of electroslag smelting has gradually increased, but the automation level of the shrinkage feeding process in electroslag remelting is still lower than that of the normal remelting process, and some shrinkage feeding processes are still manually operated. The control of the shrinkage feeding process is related to the quality of the electroslag ingot cap end. If it is not well controlled, abnormal shrinkage holes (i.e., loose areas) will appear, which will bring quality risks to the subsequent forging process, and in severe cases, it will directly cause the product to be scrapped. Summary of the invention
[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide an automatic shrinkage compensation process for Φ1000mm Ni3 type electroslag steel, which eliminates human interference, reduces the shrinkage hole depth of the cap end of the Φ1000mm Ni3 type electroslag ingot through an automatic shrinkage compensation process, and improves the quality of the cap end of the electroslag ingot.
[0005] To solve the above problems, the purpose of the present invention is achieved as follows: an automatic shrinkage feeding process for Ni3 type electroslag ingots with a specification of Φ1000mm, with the shrinkage feeding time as the center, by setting the power parameters in advance, the whole shrinkage feeding process is divided into three stages: the voltage is kept constant in the early stage, the power is gradually reduced by setting the current parameters, the current and voltage are reduced at different rates in the middle and late stages, and the temperature is kept when they are reduced to the minimum value, so as to achieve automatic shrinkage feeding, as follows: The feeding process lasts for 100-120 minutes, and the feeding weight is set to 550-600kg; the early feeding period lasts for 30-40 minutes, the current decrease rate is relatively fast, the decrease rate is 150-200A / min, and the voltage is constant; the middle feeding period lasts for 15-20 minutes, the current decrease rate is lower than that in the early period, the decrease rate is 100-125A / min, and the voltage is reduced once halfway and at the end of this stage, each time by 0.5-1V; the late feeding period lasts for 55-60 minutes, which is divided into two stages. In the first stage, the power is reduced, the decrease rate is 200-300A / min, and the voltage decrease rate is reduced by 5V every 10 minutes until it is reduced to the minimum value allowed by the equipment. The second stage is heat preservation, and the heat preservation time is ≥20 minutes.
[0006] The present invention adopts a method of reducing both the current and voltage in the middle and late stages. Ni3 is more sensitive to temperature changes. Reducing the voltage in the middle stage effectively avoids the increase in heat released by the molten pool due to the decrease in the current reduction rate in the middle stage, which leads to an increase in the melting rate during this period and affects the shrinkage effect of the molten pool. The current and voltage reduction rates in the late stage are greatly increased, further ensuring the molding of the center position of the molten pool after shrinkage. This shrinkage compensation process not only avoids the influence of human factors, but also ensures the quality of the cap end of the Ni3 electroslag ingot. DETAILED DESCRIPTION
[0007] An automatic shrinkage feeding process for Φ1000mm Ni3 type electroslag steel, the production steel type is 36CrNi3MoV, the crystallizer specification is Φ970 / Φ1040, the electrode billet specification is Φ800 continuous casting billet, the slag system is: CaF2:Al2O3:CaO=65:30:5 full pre-melted slag, the slag amount is: 480kg. The trial production quantity is 4 pieces.
[0008] At the beginning of the feeding stage, the actual voltage and current values are 49.5V and 19100A, the actual melting rate is 12kg / min, and the feeding amount is reserved for 600kg. The setting time for the early stage of feeding is 40min, the current reduction rate is set to 180A / min, and the voltage setting value is the same as the remelting period; the mid-term setting time is 20min in total, divided into 2 stages, each stage is 10min, the current reduction rate is set to 100A / min, and the voltage setting value is reduced by 1V at the end of the two stages; the late setting time is 55min in total, which is also divided into 4 stages, and the time of each stage is 10min, 10min, 10min, and 25min respectively. The first three stages are the power reduction stage, during which the current reduction rate is set to 225A / min, and the minimum current is 4000A. After the current is reduced to the minimum value, it remains constant. The voltage setting value is reduced by 5V at the end of the first three stages, and the minimum voltage is 30V, which remains constant after it is reduced to the minimum value. The fourth stage is the heat preservation stage. During the first three stages, the current and voltage are reduced to the minimum value: 4000A, 30V, and the power is kept constant for 25 minutes.
[0009] The details of the flaw detection of the trial-produced 36CrNi3MoV electroslag ingot after annealing are as follows: Table 1 36CrNi3MoV electroslag ingot flaw detection details Furnace No. Ingot type Flaw detection details 12H24735 Φ970 / 1040mm Cap shrinkage hole 0mm 12H24736 Φ970 / 1040mm Cap shrinkage hole 0mm 12H24737 Φ970 / 1040mm Cap shrinkage hole 170mm 12H24738 Φ970 / 1040mm Cap shrinkage hole 0mm The trial production results show that the shrinkage cavity depth of the 36CrNi3MoV electroslag ingot product produced by the present invention is 42.5mm on average after annealing and the shrinkage cavity depth of the electroslag ingot product produced by the conventional shrinkage feeding process is 180-200mm after annealing. It can be seen that the shrinkage feeding process of the present invention is superior to the conventional shrinkage feeding process.
Claims
1. An automatic shrinkage feeding process for Ni3 type electroslag ingot with a specification of Φ1000mm, characterized by: With the feeding time as the center, the power parameters are set in advance, and the whole feeding process is divided into three stages: the early stage of voltage is kept constant, and the power is gradually reduced by setting the current parameters. In the middle and late stages, the current and voltage are reduced at different rates, and when they are reduced to the minimum value, the temperature is kept, so as to achieve automatic feeding. The details are as follows: The feeding process lasts for 100-120 minutes, and the feeding weight is set to 550-600kg; the early feeding period lasts for 30-40 minutes, the current decrease rate is relatively fast, the decrease rate is 150-200A / min, and the voltage is constant; the middle feeding period lasts for 15-20 minutes, the current decrease rate is lower than that in the early period, the decrease rate is 100-125A / min, and the voltage is reduced once halfway and at the end of this stage, each time by 0.5-1V; the late feeding period lasts for 55-60 minutes, which is divided into two stages. In the first stage, the power is reduced, the decrease rate is 200-300A / min, and the voltage decrease rate is reduced by 5V every 10 minutes until it is reduced to the minimum value allowed by the equipment. The second stage is heat preservation, and the heat preservation time is ≥20 minutes.