CN107904412B - Preparation method of consumable electrode for electroslag remelting - Google Patents

Preparation method of consumable electrode for electroslag remelting Download PDF

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Publication number
CN107904412B
CN107904412B CN201711308106.8A CN201711308106A CN107904412B CN 107904412 B CN107904412 B CN 107904412B CN 201711308106 A CN201711308106 A CN 201711308106A CN 107904412 B CN107904412 B CN 107904412B
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temperature
consumable electrode
cooling
electrode
furnace
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CN107904412A (en
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党坤会
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Sinosteel Xingtai Machinery and Mill Roll Co Ltd
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Sinosteel Xingtai Machinery and Mill Roll Co Ltd
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    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22BPRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B9/00General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
    • C22B9/16Remelting metals
    • C22B9/18Electroslag remelting
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21DMODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/78Combined heat-treatments not provided for above
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21DMODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00Heat treatment of ferrous alloys
    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21DMODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00Microstructure comprising significant phases
    • C21D2211/009Pearlite

Abstract

The invention discloses a preparation method of a consumable electrode for electroslag remelting, which belongs to the technical field of alloy processing. The invention can ensure that the consumable electrode for the electroslag furnace does not crack in the preparation process, effectively avoids the phenomena of electrode block falling and cracking in the electroslag remelting process, improves the production efficiency and reduces the production cost.

Description

Preparation method of consumable electrode for electroslag remelting
Technical Field
The invention relates to a consumable electrode, in particular to a preparation method of the consumable electrode for electroslag remelting, belonging to the technical field of alloy processing.
Background
Electroslag remelting is a main method for preparing high-quality large alloy ingots, and the diameter of a consumable electrode required by the electroslag remelting of the large alloy ingot is larger.
The high-speed steel belongs to high-carbon and high-alloy special steel, and is applied to cold rolls due to high hardness, high wear resistance and high heat resistance. Before the end of the 20 th century, 80 s, forged high speed steel rolls have been used to manufacture the work and intermediate rolls of multi-roll mills, with smaller roll sizes. In the process of preparing large-size high-speed steel by electroslag remelting, because the alloy content is higher, the tendencies of alloy segregation, cracks and the like are greatly increased along with the increase of the product specification; secondly, with the increase of the alloy content, the thermal conductivity of the material becomes poor, and the high-speed steel is easy to crack in the manufacturing process due to thermal stress caused by the internal and external temperature difference, structural transformation stress in the heating or cooling process, uneven carbide and the like, so that the quality problems seriously restrict the development of high-speed steel preparation.
Patent document CN203316707U proposes a novel consumable electrode for electroslag remelting, which is welded and fixed below a fixed electrode by two or more consumable electrodes with hollow tubular structures, but the consumable electrode with hollow tubular structures has complex preparation process, great difficulty and high cost, and segregation cannot be eliminated in the preparation process.
Patent document CN104372177B mentions a large alloy ingot electroslag remelting tubular consumable electrode, wherein a plurality of columnar consumable electrodes with the same size and solid structure are fixedly connected to the bottom surface of an electrode group collector, the electrode group collector is fixedly connected with a fixed electrode, although a large consumable electrode is replaced by a plurality of small consumable electrodes, the combined action of the small consumable electrodes is still not completely the same as that of the large consumable electrode, the problems of segregation, cracks and the like still exist in the alloy ingot preparation process, and the problems of cracking, chipping and the like of the consumable electrodes in the preparation process still cannot be well solved.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a method for preparing the consumable electrode for electroslag remelting, so that the consumable electrode for the electroslag remelting is not cracked in the preparation process, the phenomena of electrode block falling and cracking in the electroslag remelting process are effectively avoided, the production efficiency is improved, and the production cost is reduced.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
a preparation method of a consumable electrode for electroslag remelting comprises the following steps: and (3) demoulding the steel ingot, then loading the steel ingot into a resistance furnace, carrying out isothermal preheating, then slowly heating, then rapidly cooling, and then slowly cooling.
The technical scheme of the invention is further improved as follows: the diameter of the consumable electrode is 500-750 mm.
The technical scheme of the invention is further improved as follows: the consumable electrode is made of tool and die steel with alloy content more than 8%.
The technical scheme of the invention is further improved as follows: the consumable electrode is made of high-speed steel.
The technical scheme of the invention is further improved as follows: the isothermal preheating temperature is 600-700 ℃, and the temperature is kept for 8-12 h at the temperature.
The technical scheme of the invention is further improved as follows: the temperature rising speed of the slow heating is 25-30 ℃/h, the temperature rises to 850-890 ℃, and then the heat is preserved for 10-20 h.
The technical scheme of the invention is further improved as follows: and the rapid cooling is to open a furnace door for cooling, the cooling speed is 45-55 ℃/h, and the temperature is reduced to 700-750 ℃ and then is kept for 14-20 h.
The technical scheme of the invention is further improved as follows: the slow cooling is that the temperature is firstly reduced to 200-400 ℃ along with the furnace in the resistance furnace, and then the temperature is discharged from the furnace and cooled to room temperature.
The technical scheme of the invention is further improved as follows: and polishing the steel ingot after slow cooling, heating to 400-600 ℃, preserving heat for 8-12 h, and then welding on a false electrode.
The technical scheme of the invention is further improved as follows: the hardness of the consumable electrode is 30-35 HSD.
Due to the adoption of the technical scheme, the invention has the technical progress that:
according to the preparation method of the consumable electrode for electroslag remelting, provided by the invention, the consumable electrode for the electroslag remelting is not cracked in the preparation process, and the phenomena of electrode block falling and cracking in the electroslag remelting process are effectively avoided; the consumable electrode prepared by the method has low hardness, and solves the problem that large-sized forged high-speed steel ingots are easy to crack; the production efficiency is improved and the production cost is reduced.
The preparation method has good stress relieving effect, improves the plasticity of the material, improves the structure state and prevents the cracking phenomenon. The consumable electrode has the advantages that the consumable electrode is large in specification and small in hardness, the diameter of the consumable electrode is 500-750 mm, the hardness is 30-35 HSD, and the requirement for preparing large alloy ingots is met; the invention uses less equipment, only uses one resistance furnace after the steel ingot is demoulded, the resistance furnace is common equipment for electroslag remelting, the cost is lower, the heating and fast cooling processes are all carried out in the resistance furnace, and the process is simple.
According to the invention, the steel ingot is isothermally preheated in the resistance furnace at the temperature of 600-700 ℃ for 8-12 h, so that the internal and external temperatures of the electrode are consistent, temperature preparation is made for subsequent procedures, and the electrode cracking phenomenon caused by high-temperature heating is avoided; the heating and rapid cooling steps improve the tissue state, achieve the effects of reducing hardness, eliminating internal stress and improving strong plasticity, and heat to AC1Keeping the temperature for 10-20 h at the temperature of 850-890 ℃, wherein in the temperature and temperature keeping time range, pearlite is transformed into non-uniform austenite, undissolved carbide is retained, and the mixture is quickly cooled to Ar1Keeping the temperature below (i.e. 700-750 ℃) for 14-20 hours, wherein austenite is transformed into spherical pearlite within the temperature and temperature keeping time range, and the hardness is reduced along with the transformation. Before electroslag remelting, the consumable electrode is heated up, the heating temperature is 400-600 ℃, the heat preservation time is 8-12 hours, and the electrode cracking caused by the fact that the surface temperature of the electrode rises sharply and the temperature difference between the inside and the outside is large when remelting is started is avoided within the range of the heating temperature and the heat preservation time.
The network eutectic carbide in the internal structure of the consumable electrode prepared by the invention is uniform in form and distribution, and does not crack or fall blocks in the using process, so that the whole remelting process can be smoothly carried out; the rejection rate is low, the production efficiency is further improved, and the production cost is reduced.
Detailed Description
The present invention will be described in further detail with reference to the following examples:
a consumable electrode for electroslag remelting is prepared from tool and die steel with alloy content larger than 8%, preferably high-speed steel, through proportioning according to chemical components and content of the steel, refining the steel by an electric arc furnace and an L F/VD refining furnace, bottom pouring to produce a steel ingot (consumable electrode) with the diameter of 500-750 mm, demoulding, placing the steel ingot into a resistance furnace, carrying out isothermal preheating at an isothermal preheating temperature of 600-700 ℃, carrying out heat preservation at the isothermal preheating temperature for 8-12 h, slowly heating at a heating rate of 25-30 ℃/h, heating to 850-890 ℃, carrying out heat preservation at the temperature for 10-20 h, carrying out rapid cooling at a cooling speed of 45-55 ℃/h, cooling to and carrying out heat preservation at the temperature for 14-20 h, naturally cooling to 200-400 ℃ in the resistance furnace, taking out the steel ingot, naturally cooling to room temperature in air, detecting hardness value, polishing to remove oxide skin on the surface of the furnace before use, heating to 600-600 ℃ in the resistance furnace, carrying out heat preservation at the temperature of 14-20 h, and using the consumable electrode as a dummy electrode.
Example 1
A process for preparing the consumable electrode used for electroslag remelting includes such steps as preparing high-speed steel, smelting steel in arc furnace and L F/VD refining furnace, bottom pouring to obtain steel ingot (650 mm in diameter), demoulding, loading it in electric resistance furnace, isothermal preheating at 680 deg.C for 10 hr, slowly heating to 890 deg.C at 30 deg.C/h, holding the temp for 20 hr, quickly cooling to 730 deg.C, holding the temp for 20 hr, naturally cooling to 350 deg.C, taking out the steel ingot, natural cooling to room temp in air, measuring HSD value 32, grinding to remove the oxide skin on the surface of steel ingot, heating to 500 deg.C, holding the temp for 10 hr, and welding it to false electrode.
Examples 2 to 5
Examples 2-5 were prepared similarly to example 1, except as shown in Table 1.
TABLE 1
The consumable electrode prepared in the embodiment 1-5 is used for the cold roll steel electroslag remelting production, the stable production in the whole remelting process can be ensured, and the phenomena of cracks and block falling can be avoided.
Control test
A process for preparing the consumable electrode used for electroslag remelting includes such steps as proportioning the high-speed steel, smelting in arc furnace and L F/VD refining furnace, bottom pouring to obtain steel ingot (consumable electrode) with diameter of 650mm, demoulding, heating in electric resistance furnace to 650 deg.C, holding the temp for 8 hr, discharging, cooling in air to room temp, and welding it to dummy electrode.
In order to illustrate the advantages of the invention, the consumable electrodes prepared in examples 1 to 5 and the comparative test were tested for each technical index in the electroslag remelting process, and the test results are shown in table 2.
TABLE 2
As can be seen from Table 2, the hardness of the consumable electrode prepared in the embodiments 1 to 5 of the invention is 30 to 35HSD, which is much smaller than that of 68HSD in a contrast test; the consumable electrode prepared in the embodiment 1-5 of the invention has no phenomena of chipping and cracking in the electroslag remelting process, and chipping and cracking occur in a contrast test; the detection result of the inclusions in the electroslag ingot shows that the consumable electrodes in the embodiments 1-5 of the invention have no slag inclusion, and the contrast test has slag inclusion; the results of the metallographic structure of the electrode show that all the examples 1 to 5 of the invention are lamellar pearlite, while the comparative test is spot-globular pearlite.

Claims (2)

1. A preparation method of a consumable electrode for electroslag remelting is characterized by comprising the following steps: the steel ingot is demoulded and then is loaded into a resistance furnace, isothermal preheating is carried out firstly, then heating is carried out slowly, then cooling is carried out quickly, and then cooling is carried out slowly;
the consumable electrode is made of tool and die steel with the alloy content of more than 8%;
the isothermal preheating temperature is 600-700 ℃, and the temperature is kept for 8-12 h at the temperature;
the temperature rising speed of the slow heating is 25-30 ℃/h, the temperature rises to 850-890 ℃, and then the temperature is kept for 10-20 h;
the rapid cooling is to open a furnace door for cooling, the cooling speed is 45-55 ℃/h, the temperature is reduced to 700-750 ℃, and then the temperature is kept for 14-20 h;
the slow cooling is that the temperature in the resistance furnace is reduced to 200-400 ℃ along with the furnace, and then the resistance furnace is taken out of the furnace and air-cooled to room temperature;
polishing the steel ingot after slow cooling, heating to 400-600 ℃, preserving heat for 8-12 h, and then welding on a false electrode;
the hardness of the consumable electrode is 30-35 HSD;
the diameter of the consumable electrode is 500-750 mm.
2. The method of claim 1, wherein the consumable electrode is prepared by the following steps: the consumable electrode is made of high-speed steel.
CN201711308106.8A 2017-12-11 2017-12-11 Preparation method of consumable electrode for electroslag remelting Active CN107904412B (en)

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Publication number Priority date Publication date Assignee Title
CN102477518B (en) * 2010-11-24 2014-03-12 宝钢特钢有限公司 Steel used for steam turbine blades and manufacturing method thereof
CN102758144B (en) * 2011-04-28 2014-04-02 宝钢特钢有限公司 Production method for steel ingot of large-sized high-nitrogen retaining ring steel
CN102418042B (en) * 2011-11-16 2013-06-05 抚顺特殊钢股份有限公司 Novel manufacturing process of phi 300 mm-phi 700 mm high-carbon high-chromium cold-working die steel forged round steel
CN102912236B (en) * 2012-11-13 2014-05-07 北京科技大学 High-performance and abrasion-resistant hot work die steel and technology for manufacturing same
CN105755391A (en) * 2016-05-16 2016-07-13 昆山双儒模具科技有限公司 Novel high-speed steel material and preparation process thereof

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