Novel electroslag furnace base protection plate for nickel-based alloy

Abstract

The invention discloses a novel electroslag furnace base protection plate for a nickel-based alloy, and aims to solve the problem that residual iron elements at the bottom cushion end of a steel ingot rise and exceed the standard due to melting of an iron base protection plate in the smelting process of a nickel-based alloy large-specification electroslag ingot. According to the specific technical scheme, the novel electroslag furnace base protection plate universal for two groups of nickel-based alloys is invented, and the protection plate is made of an intermediate alloy of N -Cr-Fe and an intermediate alloy of N -Cr; the intermediate alloy is smelted by adopting a non-vacuum induction + LF + VOD process, and is forged and rolled into a hot-rolled plate; and the intermediate alloy hot-rolled plate is cut into the protection plate according to the actual ingot type requirement. The intermediate alloy protection plate has the beneficial effects that the component formula of the intermediate alloy protection plate is highly matched with that of nickel-based alloy, the production process is simple, and manufacturing is easy; the problems that in the nickel-based alloy large-specification electroslag ingot smelting process, due to the fact that an iron base protection plate is melted, residual iron elements at the bottom cushion end of a steel ingot rise and exceed the standard are solved.

Description

Technical Field

[0001] The invention belongs to the field of electroslag smelting of nickel-based corrosion-resistant and high-temperature alloy materials, and in particular relates to a novel electroslag furnace base protection plate for nickel-based alloys. Background Art

[0002] Nickel-based corrosion-resistant and high-temperature alloys are smelted by electroslag remelting, which can effectively remove large non-metallic inclusions and impurity sulfur in the consumable electrode. The molten metal is forced to cool and solidify in a water-cooled crystallizer to obtain a dense crystalline structure with slight macro-segregation and a smooth ingot surface. At present, the mainstream electroslag furnace for smelting nickel-based corrosion-resistant and high-temperature alloys in China is generally a single-arm constant melting rate electroslag furnace (protective atmosphere and non-protective atmosphere), with an electroslag furnace tonnage of 3t to 30t; whether it is domestic or imported single-arm constant melting rate electroslag furnace, in the process design, it is required to use a corresponding conductive guard plate on the base of the electroslag furnace, the thickness of the guard plate is 10mm to 25mm, and the material is Q235. Through production practice, it is found that when using this type of electroslag furnace to smelt nickel-based corrosion-resistant and high-temperature alloys, due to the low original iron content requirements in the alloy (such as: GH3128, N06625, N10276, N06600, etc.), the electroslag furnace base protection plate made of Q235 material in the early stage of smelting will partially melt and enter the bottom pad end of the steel ingot, resulting in an increase in the iron element at the bottom pad end of the electroslag ingot or even exceeding the standard, which seriously affects the utilization rate of the steel ingot. At the same time, as the size of the steel ingot increases, the loss rate of each furnace steel ingot due to excessive iron content will reach 10% to 32%. Due to the high cost of nickel-based alloys, it will bring great economic losses to the company.

[0003] Taking N06600 as an example, the alloy contains 6% to 10% iron. When the iron composition of the electrode billet is controlled at 8% on the center line, during the electroslag remelting process, the melting of the Q235 base protection plate will cause the iron content in the 150mm length range of the bottom pad end of the Φ610mm (3.7 tons) steel ingot to exceed the standard, and the steel ingot utilization rate will be lost by 10% to 11%; the iron content in the 220mm length range of the bottom pad end of the Φ750mm (5.5 tons) steel ingot exceeds the standard, and the steel ingot utilization rate loses by 14% to 15%; the iron content in the 310mm length range of the bottom pad end of the Φ930mm (10-12 tons) steel ingot exceeds the standard, and the steel ingot utilization rate loses by 30% to 32%.

[0004] At present, the demand for super-large size (over 3t) nickel-based alloy electroslag ingots is increasing, and it is urgent to solve the problem of smelting iron increase of nickel-based alloy electroslag furnace base protection plate, especially the iron (Q235) electroslag furnace base protection plate. Summary of the invention

[0005] The invention discloses a novel electroslag furnace base protection plate for nickel-based alloys, aiming to solve the problem of increase and excessive residual iron element at the bottom pad end of the ingot due to melting of the iron base protection plate during the smelting process of large-size electroslag ingots of nickel-based alloys.

[0006] Specific technical solutions adopted:

[0007] According to the characteristics of the proportion of nickel-based alloy components, and combined with the change law of the increase of residual iron elements at the bottom pad end of the steel ingot caused by the melting of the iron base guard plate, two sets of new electroslag furnace base protection plates for nickel-based alloys were invented. The protection plate material is "Ni-Cr-Fe" and "Ni-Cr" intermediate alloys, and the chemical composition meets the requirements of Table 1; the intermediate alloy is smelted by "non-vacuum induction + LF + VOD" process and "forged + rolled" into hot-rolled plates; the intermediate alloy hot-rolled plates are cut into protection plates according to the actual ingot shape requirements, and the effective size range is shown in Table 2.

[0008] Table 1

[0009]

[0010] Table 2

[0011] Nominal thickness(mm) Diameter(mm) 25±0.5 700～1100±3

[0012] The invention points:

[0013] ⑴ The material of the new type of electroslag furnace base protection plate is "Ni-Cr-Fe" and "Ni-Cr" intermediate alloys. The main elements of nickel and chromium are the main beneficial elements in high-temperature alloys. After melting, entering the molten steel is equivalent to slightly adjusting the alloying elements, which has no effect on the main element control target in subsequent production; ⑵ For nickel-based alloys where the lower the iron content, the better the residual control, the O# intermediate alloy is designed. Its iron element control below 0.3% can ensure that the iron element increase brought by the protection plate entering the molten steel after melting is only below 0.03%, which will not affect the product quality control level; ⑶ For nickel-based alloys with a clear control range of iron content, the 1# intermediate alloy is designed. Its 8% to 10% iron element control can further reduce the manufacturing cost relative to the 0# intermediate alloy on the premise of ensuring that the iron element increase brought by the protection plate entering the molten steel after melting does not exceed 0.2%; ⑷ The control requirements of harmful elements (lead, arsenic, tin, antimony, bismuth, selenium) and gas elements (oxygen, nitrogen) of nickel-based alloys are optimized and designed, which can significantly improve the "Ni-Cr-Fe" and "Ni-Cr-Fe" i-Cr" alloy thermoplasticity, avoiding the risk of cracking during plate processing, and preventing the excessive harmful elements and gases in high-temperature alloy steel liquid during use, affecting the plasticity of the final product; ⑸ Considering the high value of "Ni-Cr-Fe" and "Ni-Cr" alloy raw materials, the design adopts "non-vacuum induction

[0014] +LF+VOD” process is used for smelting and direct casting of steel ingots to reduce metal loss during smelting and casting.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] The composition formula of the intermediate alloy protection plate of the present invention is highly matched with the nickel-based alloy, the production process is simple and easy to manufacture; it solves the problem of increase and excessive residual iron elements at the bottom pad end of the steel ingot caused by melting of the iron base protection plate during the smelting process of large-sized nickel-based alloy electroslag ingots. DETAILED DESCRIPTION

[0017] The present invention is further described in detail with reference to specific embodiments.

[0018] Embodiment 1:

[0019] Table 3 shows the chemical composition comparison before and after smelting N06625 alloy Φ750mm electroslag ingot using 0# master alloy electroslag furnace base protection plate.

[0020] Table 3

[0021]

[0022] Embodiment 2:

[0023] Table 4 shows the chemical composition comparison before and after smelting N06690 alloy Φ930mm electroslag ingot using 1# master alloy electroslag furnace base protection plate.

[0024] Table 4

[0025]

Claims

1. A new type of electroslag furnace base protection plate for nickel-based alloy, characterized in that: The protective plates are divided into two groups, and the materials are 1 # Master alloy "Ni-Cr-Fe" and 0 # Master alloy "Ni-Cr" master alloy, chemical composition conforms to the provisions of Table 1; Table 1 The intermediate alloy is smelted by "non-vacuum induction + LF + VOD" process and is made into hot-rolled plates by "forging + rolling". The intermediate alloy hot-rolled plates are cut into protective plates according to the actual ingot shape requirements, with a nominal thickness of 25mm±0.5mm and a diameter of (700~1100)mm±3mm.

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