Welding molybdenum plate and preparation method thereof

Abstract

The invention discloses a welding molybdenum plate and a preparation method thereof, and belongs to the technical field of metal material processing. The preparation method comprises the following steps: carrying out vacuum annealing treatment, multi-pass hot rolling treatment and cold rolling treatment on a high-purity molybdenum blank to obtain a raw material molybdenum plate; and the raw material molybdenum plate is sequentially subjected to cleaning, preheating and inert atmosphere gas supply treatment, then welding is conducted in a low-frequency pulse welding mode under the conditions that the current range is 140-160 A and the welding speed is 3-5 mm / s, and the welded molybdenum plate is obtained. The welding seam of the obtained welding molybdenum plate is uniform, smooth and free of cracks and macroscopic pores, and the high-end application requirement is met.

Description

Technical Field

[0001] This invention relates to the technical field of metal material processing, and in particular to a method for welding molybdenum plates. Background Technology

[0002] Molybdenum, as an important refractory metal material, is widely used in aerospace, nuclear industry and electronic devices. Its welding quality directly affects the performance and reliability of products. At present, the existing technology for welding molybdenum plates has obvious defects, including: (1) macroscopic pores are easily formed at the weld, which destroys the joint density and mechanical properties; (2) the uniformity of the welding temperature field distribution is not good, which easily leads to the instability of the molten pool and causes unevenness in weld width, penetration depth and surface ripples; (3) the welding thermal cycle easily coarsens the grains in the heat-affected zone and generates hot cracks and cold cracks during the cooling process, especially at the junction of the weld and the base material; (4) oxide inclusions are easily generated during the welding process, and the traditional process often separates the material preparation and welding process, without considering the influence of the preceding processes such as rolling and heat treatment on the welding performance, which makes it difficult to systematically control the weld quality.

[0003] With the increasing demands for molybdenum products in high-end applications, it is desirable to obtain welded molybdenum plates with welds that are completely free of macroscopic porosity, have a uniform and smooth surface, are free of cracks and defects, and have joint mechanical properties that are no less than 90% of those of the base material. However, existing technologies can no longer meet these requirements. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a new method for welding molybdenum plates, which systematically integrates material preparation and welding process, and achieves high-quality welding of molybdenum plates with no macroscopic pores, uniform smoothness and no cracks, thus meeting the needs of high-end applications.

[0005] The technical solution of the present invention is as follows: A method for preparing a welded molybdenum plate, comprising: (1) Using molybdenum billets with a molybdenum content greater than 99wt% as raw materials, vacuum annealing them at 900-1100℃ is performed to obtain annealed molybdenum billets; (2) The annealed molybdenum billet is subjected to multiple hot rolling processes with one pass each until its thickness reaches 1.5-3 mm to obtain a hot-rolled molybdenum billet; wherein the heating temperature of the first pass, i.e. the billet opening temperature, is 1200-1400℃, the rolling deformation rate of the first pass is 20-25%, the rolling deformation rate of each subsequent pass is 15-20%, the heating temperature of each pass is 900-1100℃, and the heating is carried out in a reducing atmosphere; (3) The hot-rolled molybdenum billet is subjected to cold rolling treatment to make its cold rolling deformation rate reach 30-40% to obtain raw molybdenum plate; (4) Welding the raw material molybdenum plate, the welding includes: cleaning the raw material molybdenum plate to obtain a clean molybdenum plate; preheating the clean molybdenum plate to obtain a preheated molybdenum plate; setting a clean, uncontaminated tungsten electrode in the shape of a needle tip at a distance of 1.5-2.5 mm perpendicular to the preheated molybdenum plate, and then supplying gas to the welding area using an inert atmosphere at a flow rate of 5-15 L / min; then welding is performed using a low-frequency pulse welding method under conditions of a current range of 140-160 A and a welding speed of 3-5 mm / s; thus obtaining a welded molybdenum plate.

[0006] According to some preferred embodiments of the present invention, the heating in step (2) is carried out in a hydrogen heating furnace.

[0007] According to some preferred embodiments of the present invention, the cleaning includes cleaning the raw molybdenum plate sequentially with a cleaning agent and alcohol.

[0008] According to some preferred embodiments of the present invention, the temperature of the preheating treatment is 100-120°C.

[0009] According to some preferred embodiments of the present invention, the inert atmosphere is argon.

[0010] According to some preferred embodiments of the present invention, the current exchange frequency of the low-frequency pulse welding method is 0.5-0.7Hz.

[0011] According to some preferred embodiments of the present invention, the welding speed is 3.5 mm / s.

[0012] The present invention further provides a welded molybdenum plate prepared according to the above preparation method.

[0013] The weld of the molybdenum plate is uniform, smooth, crack-free, and free of macroscopic pores.

[0014] The beneficial effects of this invention include: This invention obtains a molybdenum plate with a uniform and dense structure that is conducive to welding by vacuum annealing, optimized hot rolling and cold rolling of high-purity molybdenum billets; subsequently, by combining cleaning, preheating, the formation of local oxygen-free zones and a low-frequency pulse welding mode, the weld pool and thermal process are precisely controlled, and the material preparation and welding process are synergistically integrated to obtain a welded molybdenum plate with uniform, smooth, crack-free and macro-porosity-free weld, which meets the requirements of high-end applications. Attached Figure Description

[0015] Figure 1 This is a physical image of the welded molybdenum plate obtained in Example 1; Figure 2 This is a physical image of the welded molybdenum plate obtained in Example 2; Figure 3 This is a physical image of the welded molybdenum plate obtained in Example 3; Figure 4 The image shows the actual welded molybdenum plate obtained in Comparative Example 1. Figure 5 The image shows the actual welded molybdenum plate obtained in Comparative Example 2. Figure 6 The image shows the actual welded molybdenum plate obtained in Comparative Example 3. Figure 7 This is a physical image of the welded molybdenum plate obtained in Comparative Example 4. Detailed Implementation

[0016] The present invention will be further described in detail below through specific embodiments, but it should not be construed as limiting the scope of the invention to the following examples. Various substitutions or modifications made based on ordinary technical knowledge and conventional methods in the art without departing from the above-described methodological spirit of the invention should be included within the scope of the invention.

[0017] Example 1 The welded molybdenum plate is prepared by the following steps: (1) A molybdenum billet with a thickness of 35 mm (T35) and a molybdenum content greater than 99% is subjected to vacuum annealing at 900℃ to obtain an annealed molybdenum billet; (2) The annealed molybdenum billet is hot rolled by a rolling mill until its thickness reaches 1.7 mm (T1.7). The billet temperature during the process is 1400℃, the deformation amount of the first pass is 20%, the deformation amount of each subsequent pass is controlled at 15%, the heating temperature of each pass is 1100℃, the heating is carried out by a hydrogen heating furnace, and the rolling is carried out in one pass to obtain the hot-rolled molybdenum billet; (3) The obtained hot-rolled molybdenum billet is subjected to multiple cold rolling processes until its total deformation reaches 40% to obtain raw molybdenum plate; (4) Weld the obtained raw material molybdenum plate. The welding process includes: using a cleaning agent to remove the oxide on the surface of the raw material molybdenum plate and wiping it with alcohol. Then, fix it on the workbench for preheating treatment. The preheating temperature is 100℃ to obtain the preheated molybdenum plate. Move the welding robot to the starting point, and then adjust the head to be needle-shaped, clean and free of dirt. The tungsten electrode is perpendicular to the preheated molybdenum plate and the distance is 2mm. Then, argon gas is sent to the welding area at a flow rate of 10L / min to form a local oxygen-free area. Then, a low-frequency pulse welding method with a current exchange frequency of 0.7Hz is selected, and welding is carried out under the conditions of a current range of 140-160A and a welding speed of 3.5mm / s.

[0018] The resulting welded molybdenum plate is shown in the attached figure. Figure 1 As shown, through the attached Figure 1 It can be seen that the weld seam in the obtained welded molybdenum plate is uniform, smooth, without cracks, and without macroscopic pores.

[0019] Example 2 The welded molybdenum plate is prepared by the following steps: (1) A molybdenum billet with a thickness of 35 mm (T35) and a molybdenum content greater than 99% is subjected to vacuum annealing at 1100℃ to obtain an annealed molybdenum billet; (2) The annealed molybdenum billet is hot rolled by a rolling mill until its thickness reaches 1.7 mm (T1.7). The billet temperature during the process is 1200℃, the deformation amount of the first pass is 25%, the deformation amount of each subsequent pass is controlled at 20%, the heating temperature of each pass is 900℃, the heating is carried out by a hydrogen heating furnace, and the rolling is carried out in one pass to obtain the hot-rolled molybdenum billet; (3) The obtained hot-rolled molybdenum billet is cold-rolled until its total deformation reaches 35% to obtain raw molybdenum plate; (4) Weld the obtained raw material molybdenum plate. The welding process includes: using a cleaning agent to remove the oxide on the surface of the raw material molybdenum plate and wiping it with alcohol. Then, fix it on the workbench for preheating treatment. The preheating temperature is 120℃ to obtain the preheated molybdenum plate. Move the welding robot to the starting point, and then adjust the head to be needle-shaped, clean and free of dirt. The tungsten electrode is perpendicular to the preheated molybdenum plate and the distance is 2mm. Then, argon gas is sent to the welding area at a flow rate of 10L / min to form a local oxygen-free area. Then, a low-frequency pulse welding method with a current exchange frequency of 0.7Hz is selected, and welding is carried out under the conditions of a current range of 140-150A and a welding speed of 3.5mm / s.

[0020] The resulting welded molybdenum plate is shown in the attached figure. Figure 2 As shown, through the attached Figure 2 It can be seen that the weld seam in the obtained welded molybdenum plate is uniform, smooth, without cracks, and without macroscopic pores.

[0021] Example 3 The welded molybdenum plate is prepared by the following steps: (1) A molybdenum billet with a thickness of 35 mm (T35) and a molybdenum content greater than 99% is subjected to vacuum annealing at 1000℃ to obtain an annealed molybdenum billet; (2) The annealed molybdenum billet is hot rolled by a rolling mill until its thickness reaches 1.7 mm (T1.7) (processed to T1.7). The billet temperature during the process is 1300℃, the deformation amount of the first pass is 23%, the deformation amount of each subsequent pass is controlled at 17%, the heating temperature of each pass is 1000℃, the heating is carried out by a hydrogen heating furnace, and the rolling is carried out in one pass with one heat to obtain the hot-rolled molybdenum billet; (3) The obtained hot-rolled molybdenum billet is cold-rolled until its total deformation reaches 30% to obtain raw molybdenum plate; (4) Weld the obtained raw material molybdenum plate. The welding process includes: using a cleaning agent to remove the oxide on the surface of the raw material molybdenum plate and wiping it with alcohol. Then, fix it on the workbench for preheating treatment. The preheating temperature is 110℃ to obtain the preheated molybdenum plate. Move the welding robot to the starting point, and then adjust the head to be needle-shaped, clean and free of dirt. The tungsten electrode is perpendicular to the preheated molybdenum plate and the distance is 2mm. Then, argon gas is supplied to the welding area at a flow rate of 10L / min to form a local oxygen-free area. Then, a low-frequency pulse welding method with a current exchange frequency of 0.5Hz is selected, and welding is performed under the conditions of a current range of 150-160A and a welding speed of 3.5mm / s.

[0022] The resulting welded molybdenum plate is shown in the attached figure. Figure 3 As shown, through the attached Figure 3 It can be seen that the weld seam in the obtained welded molybdenum plate is uniform, smooth, without cracks, and without macroscopic pores.

[0023] Comparative Example 1 The welding molybdenum plate was prepared using the same process as in Example 1, except that: the annealing treatment in step (1) was performed using conventional annealing with nitrogen at 850°C; and the current during low-frequency pulse welding in step (4) was 110A.

[0024] The resulting welded molybdenum plate is shown in the attached figure. Figure 4 As shown, through the attached Figure 4 It can be seen that there are pores in the weld of the obtained welded molybdenum plate.

[0025] Comparative Example 2 The welded molybdenum plate was prepared using the same process as in Example 1, except that: in the hot rolling process of step (2), the heating was carried out by an electric heating furnace; and the current was 170A when performing low-frequency pulse welding in step (4).

[0026] The resulting welded molybdenum plate is shown in the attached figure. Figure 5 As shown, through the attached Figure 5 It can be seen that the weld of the obtained welded molybdenum plate showed phenomena of incomplete fusion and uneven welding.

[0027] Comparative Example 3 Welded molybdenum plates were prepared using the same process as in Example 1, except that the hot rolling process in step (2) was performed in a single pass with multiple heats; and the welding speed in step (4) was 2.5 m / s.

[0028] The resulting welded molybdenum plate is shown in the attached figure. Figure 6 As shown, through the attached Figure 6 It can be seen that the weld of the obtained welded molybdenum plate showed phenomena of incomplete fusion and uneven welding.

[0029] Comparative Example 4 The welded molybdenum plate was prepared using the same process as in Example 1, except that the annealing treatment in step (1) was performed using conventional annealing with nitrogen at 850°C; and the welding speed in step (4) was 5.5 m / s.

[0030] The resulting welded molybdenum plate is shown in the attached figure. Figure 7 As shown, through the attached Figure 7 It can be seen that the obtained welded molybdenum plates exhibit weld penetration, spatter, and incomplete welds.

[0031] The above embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a welded molybdenum plate, characterized in that, It includes: (1) Using molybdenum billets with a molybdenum content greater than 99wt% as raw materials, vacuum annealing them at 900-1100℃ is performed to obtain annealed molybdenum billets; (2) The annealed molybdenum billet is subjected to multiple hot rolling processes with one pass each until its thickness reaches 1.5-3 mm to obtain a hot-rolled molybdenum billet; wherein the heating temperature of the first pass, i.e. the billet opening temperature, is 1200-1400℃, the rolling deformation rate of the first pass is 20-25%, the rolling deformation rate of each subsequent pass is 15-20%, the heating temperature of each pass is 900-1100℃, and the heating is carried out in a reducing atmosphere; (3) The hot-rolled molybdenum billet is subjected to cold rolling treatment to make its cold rolling deformation rate reach 30-40% to obtain raw molybdenum plate; (4) Welding the raw material molybdenum plate, the welding includes: cleaning the raw material molybdenum plate to obtain a clean molybdenum plate; preheating the clean molybdenum plate to obtain a preheated molybdenum plate; setting a clean, uncontaminated tungsten electrode in the shape of a needle tip at a distance of 1.5-2.5 mm perpendicular to the preheated molybdenum plate, and then supplying gas to the welding area using an inert atmosphere at a flow rate of 5-15 L / min; then welding is performed using a low-frequency pulse welding method under conditions of a current range of 140-160 A and a welding speed of 3-5 mm / s; thus obtaining a welded molybdenum plate.

2. The preparation method according to claim 1, characterized in that, The heating described in step (2) is carried out in a hydrogen heating furnace.

3. The preparation method according to claim 1, characterized in that, The cleaning process includes cleaning the raw molybdenum plate sequentially with a cleaning agent and then with alcohol.

4. The preparation method according to claim 1, characterized in that, The preheating temperature is 100-120℃.

5. The preparation method according to claim 1, characterized in that, The inert atmosphere is argon.

6. The preparation method according to claim 1, characterized in that, The current exchange frequency of the low-frequency pulse welding method is 0.5-0.7Hz.

7. The preparation method according to claim 1, characterized in that, The welding speed is 3.5 mm / s.

8. The welded molybdenum plate prepared by the preparation method according to any one of claims 1-7.

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