Fusion casting method for reducing TA1 cold rolling wrinkle defect of VAR blank

Abstract

The invention relates to a casting method for reducing TA1 cold rolling wrinkle defects of a VAR blank, which comprises the following steps: S1, carrying out color sorting on sponge titanium required by smelting, and removing the sponge titanium with abnormal color; s2, pressing an electrode block through a vertical / horizontal press, and welding the electrode block into a primary smelting electrode by adopting a vacuum arc or a vacuum electron beam; s3, yellow and blue oxides at the welding seam of the primary smelting electrode are thoroughly polished; s4, primary smelting; s5, a titanium ingot obtained after primary smelting is used as a secondary smelting electrode after volatile matter at an ingot body and a dead head and yellow and blued oxide layers are thoroughly removed; s6, secondary smelting is conducted; wherein the direction of the secondary smelting electrode is consistent with the direction of the primary smelting electrode. According to the method, melting removal of low-density inclusions can be effectively promoted, center segregation of the inclusions is reduced, and therefore the occurrence rate of wrinkle defects in the VAR blank cold rolling process is reduced, and the cold rolling quality and the yield are improved.

Description

Technical Field

[0001] The invention relates to the technical field of titanium and titanium alloy smelting, and in particular to a smelting and casting method for reducing cold-rolled wrinkle defects of VAR billet TA1. Background Art

[0002] Titanium is a strong and light metal with the unique advantages of high specific strength, good high and low temperature resistance and strong corrosion resistance. Its application volume and the level of development of the titanium industry have become important indicators of a country's comprehensive strength. With the increasing demand for high-end materials in the manufacturing industry, the application of titanium in military, civilian and other fields has become more and more extensive. As a high-value-added product of titanium coils, cold-rolled titanium coils have attracted much attention from titanium companies. The quality of cold-rolled titanium coils is a comprehensive reflection of the company's full-process control level.

[0003] TA1 cold rolled coil has been widely used in civilian products and daily life due to its excellent plasticity, biocompatibility and deep drawing performance. Except for a few enterprises that can produce billets suitable for cold rolling through EB furnace smelting, TA1 cold rolled coil is mainly obtained by hot rolling and cold rolling of VAR forging billets.

[0004] However, wrinkle defects often occur during cold rolling of VAR billets, which seriously reduce the yield of cold-rolled coils. Statistical analysis shows that wrinkle defects mostly occur in the center of the width direction of the cold-rolled coil and appear intermittently along the rolling direction. Microscopic analysis of wrinkle defects shows that there is an oxygen-rich hard α phase region at the defect, and its hardness is much higher than that of the matrix. After analysis, the cause of wrinkle defects is directly related to the failure to completely remove low-density titanium oxide inclusions during VAR smelting and their segregation to the core of the molten pool. Clean production, smelting process and dynamic conditions in the molten pool during VAR production are also crucial to the movement and removal behavior of inclusions. Summary of the invention

[0005] In view of the above problems, the object of the present invention is to provide a melting and casting method for reducing the wrinkle defects of VAR billet TA1 cold rolling, which can effectively promote the introduction, melting removal and dispersion distribution of low-density inclusions, reduce the central concentration of inclusions, thereby reducing the incidence of wrinkle defects in the cold rolling process of VAR billet, and improving the cold rolling quality and yield.

[0006] The technical solution adopted by the present invention is as follows:

[0007] The present invention proposes a melting and casting method for reducing the cold-rolled wrinkle defects of VAR billet TA1, which specifically comprises the following steps:

[0008] S1. Color sorting of titanium sponge required for smelting to remove titanium sponge with abnormal color;

[0009] S2. Pressing the electrode block by a vertical / horizontal press, and welding the electrode block into a primary melting electrode by a vacuum arc or a vacuum electron beam;

[0010] S3. Thoroughly grind the yellow and blue oxides at the welding seam of the melting electrode;

[0011] S4, primary smelting;

[0012] S5. The titanium ingot obtained after the primary smelting is used as a secondary smelting electrode after the volatiles in the ingot body and the riser and the yellow and blue oxide layers are completely removed;

[0013] S6. Secondary smelting; wherein the direction of the secondary smelting electrode is consistent with the direction of the primary smelting electrode.

[0014] Furthermore, in step S1, the titanium sponge with abnormal color is yellow, dark and bluish titanium sponge.

[0015] Furthermore, in step S4, an AC arc stabilization process is used for primary smelting, with a smelting voltage of 32-36V, a smelting current of 15-30kA, an arc stabilization magnetic field of 2-4mT, a stirring frequency of 20-40s, and a smelting power density per unit area of ​​the smelting electrode of 1.0-1.5W / mm2.

[0016] Furthermore, in step S6, the secondary smelting adopts an AC stable arc process, with a smelting voltage of 34-40V, a smelting current of 35-42kA, an arc-stabilizing magnetic field of 3-5mT, a stirring frequency of 15-50s, and a smelting power density per unit area of ​​the smelting electrode of 1.4-1.8W / mm 2 .

[0017] Furthermore, before the primary smelting, the primary smelting electrode is dried in an oven at 130-250° C. for 3-5 hours, and the smelting crucible is cleaned to ensure that there is no impurity.

[0018] Furthermore, before the secondary smelting, the secondary smelting electrode is dried in an oven at 130-250° C. for 2-5 hours.

[0019] Furthermore, the diameter of the primary smelting electrode is 800-1050 mm; the diameter of the secondary smelting electrode is 850-1150 mm.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention proposes a melting and casting method for reducing the wrinkle defects of VAR billet TA1 cold rolling, which can effectively promote the melting and removal of low-density inclusions, make the inclusions in the VAR molten pool dispersed, effectively reduce the center segregation behavior of the inclusions, thereby effectively reducing the probability of wrinkle defects in the cold rolling process of the VAR billet and improving the cold rolling quality and yield rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the distribution of inclusions in the molten pool of the existing smelting and casting method VAR;

[0023] Figure 2 Schematic diagram of the distribution of inclusions in the VAR molten pool after the melting and casting method of the present invention is adopted.

[0024] Among them, the figure numbers are: 1-VAR melt pool; 2-inclusion distribution trend of existing melting and casting method; 3-inclusion distribution trend of the present invention. DETAILED DESCRIPTION

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] See attached Figure 1 The present invention proposes a melting and casting method for reducing the cold rolling wrinkle defects of VAR billet TA1, which specifically comprises the following steps:

[0027] S1. Color sorting is performed on the titanium sponge required for smelting to remove titanium sponge with abnormal color; wherein, titanium sponge with abnormal color is yellow, dark and blue titanium sponge.

[0028] S2. Pressing the electrode block by a vertical / horizontal press, and welding the electrode block into a primary melting electrode by a vacuum arc or a vacuum electron beam; the diameter of the primary melting electrode is 800-1050 mm.

[0029] S3. Thoroughly grind the yellow and blue oxides at the welding seam of the melting electrode;

[0030] S4, primary smelting;

[0031] First, before the first smelting, dry the first smelting electrode in a 130-250℃ oven for 3-5h, clean the smelting crucible, and make sure there is no impurities before the first smelting;

[0032] The primary smelting adopts AC stable arc process, the smelting voltage is 32-36V, the smelting current is 15-30kA, the arc stable magnetic field is between 2-4mT, the stirring frequency is 20-40s, and the smelting power density per unit area of ​​the smelting electrode is 1.0-1.5W / mm 2 .

[0033] S5. The titanium ingot obtained after the primary smelting is used as a secondary smelting electrode after the volatiles in the ingot body and the riser and the yellow and blue oxide layers are completely removed; the diameter of the secondary smelting electrode is 850-1150mm.

[0034] S6, secondary smelting;

[0035] First, before the secondary smelting, the secondary smelting electrode is dried in an oven at 130-250°C for 2-5 hours;

[0036] The direction of the secondary smelting electrode remains consistent with the direction of the primary smelting electrode;

[0037] The secondary smelting adopts AC stable arc process, the smelting voltage is 34-40V, the smelting current is 35-42kA, the stable arc magnetic field is between 3-5mT, the stirring frequency is 15-50s, and the smelting power density per unit area of ​​the smelting electrode is 1.4-1.8W / mm 2 .

[0038] The technical solution of the present invention is further described below by means of specific examples:

[0039] Example 1

[0040] For a 10t VAR furnace, in actual production, 9t heavy cold-rolled TA1 billet is melted, the primary ingot electrode diameter is 900mm, and the secondary ingot electrode diameter is 980mm; the primary melting voltage is 32V, the melting current is 25kA, the primary melting arc magnetic field intensity is 3mT, the stirring cycle is 30s, and the power density of the primary melting is 1.258W / mm 2 The secondary melting voltage is 34V, the melting current is 38kA, the secondary arc stabilizing magnetic field strength is 3.5mT, the stirring cycle is 20s, and the power density of the secondary melting is 1.714W / mm 2 The smelted VAR billet is forged, hot rolled and cold rolled to a 1.0 mm cold rolled coil, and no wrinkle defects appear in the whole coil.

[0041] Example 2

[0042] For a 15t VAR furnace, in actual production, 10t of TA1 billet for heavy cold rolling is melted, the diameter of the primary ingot electrode is 980mm, and the diameter of the secondary ingot electrode is 1050mm; the primary melting voltage is 35V, the melting current is 28kA, the primary melting arc stabilizing magnetic field strength is 3.5mT, the stirring cycle is 30s, and the power density of the primary melting is 1.258W / mm2. The secondary melting voltage is 37V, the melting current is 40kA, the secondary arc stabilizing magnetic field strength is 4.3mT, the stirring cycle is 15s, and the power density of the secondary melting is 1.71W / mm2. The smelted VAR billet is forged, hot rolled and cold rolled, and then rolled to a 0.5mm specification cold rolled coil, and no wrinkle defects appear in the whole coil.

[0043] The working principle of the present invention is:

[0044] (1) Improve the smelting power density and promote the dissolution of low-density inclusions;

[0045] (2) Use AC stirring to promote the dispersion of inclusions;

[0046] (3) Removing yellow, dark, and bluish sponge titanium, grinding the primary and secondary melting electrodes, removing the yellow / bluish oxide layer, and adopting drying measures can effectively reduce the introduction of low-density inclusions, thereby reducing the impact of inclusions on cold rolling quality.

[0047] Matters not described in detail in the present invention are all known technologies.

[0048] The embodiments described above are merely descriptions of preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A casting method for reducing cold-rolled wrinkle defects of VAR billet TA1, characterized in that: The method comprises the following steps: S1. Color sorting of titanium sponge required for smelting to remove titanium sponge with abnormal color; S2. Pressing the electrode block by a vertical / horizontal press, and welding the electrode block into a primary melting electrode by a vacuum arc or a vacuum electron beam; S3. Thoroughly grind the yellow and blue oxides at the welding seam of the melting electrode; S4, primary smelting; S5. The titanium ingot obtained after the primary smelting is used as a secondary smelting electrode after the volatiles in the ingot body and the riser and the yellow and blue oxide layers are completely removed; S6. Secondary smelting; wherein the direction of the secondary smelting electrode is consistent with the direction of the primary smelting electrode.

2. A melting and casting method for reducing cold rolling wrinkle defects of VAR billet TA1 according to claim 1, characterized in that: In the step S1, the titanium sponge with abnormal color is yellow, dark and blue titanium sponge.

3. A melting and casting method for reducing cold rolling wrinkle defects of VAR billet TA1 according to claim 1, characterized in that: In step S4, the first smelting adopts an AC stable arc process, the smelting voltage is 32-36V, the smelting current is 15-30kA, the arc stable magnetic field is between 2-4mT, the stirring frequency is 20-40s, and the smelting power density per unit area of ​​the smelting electrode is 1.0-1.5W / mm 2 .

4. A melting and casting method for reducing cold rolling wrinkle defects of VAR billet TA1 according to claim 1, characterized in that: In step S6, the secondary smelting adopts an AC stable arc process, with a smelting voltage of 34-40V, a smelting current of 35-42kA, an arc stable magnetic field of 3-5mT, a stirring frequency of 15-50s, and a smelting power density per unit area of ​​the smelting electrode of 1.4-1.8W / mm 2 .

5. A melting and casting method for reducing cold rolling wrinkle defects of VAR billet TA1 according to claim 1, characterized in that: Before the primary smelting, the primary smelting electrode is dried in an oven at 130-250° C. for 3-5 hours, and the smelting crucible is cleaned to ensure that there is no impurity.

6. A melting and casting method for reducing cold rolling wrinkle defects of VAR billet TA1 according to claim 1, characterized in that: Before the secondary smelting, the secondary smelting electrode is dried in an oven at 130-250° C. for 2-5 hours.

7. A melting and casting method for reducing cold rolling wrinkle defects of VAR billet TA1 according to claim 1, characterized in that: The diameter of the primary smelting electrode is 800-1050 mm; the diameter of the secondary smelting electrode is 850-1150 mm.

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