Titanium alloy test rod and manufacturing method

Abstract

The present invention belongs to the technical field of special alloy castings, and specifically relates to a titanium alloy test rod and a manufacturing method. The titanium alloy test rod provided by the present invention is cut off from the outside after being cast in a centrifugal field. The titanium alloy test rod is strip-shaped as a whole, and includes a first fixed section, a working section, a second fixed section, and a casting section which are integrally connected to each other from top to bottom; the thickness of the first fixed section and the second fixed section are both greater than the working section, and the first fixed section and the second fixed section are smoothly connected to the working section; the upper end of the casting section is the same thickness as the second fixed section, and the thickness gradually increases from top to bottom. The qualified rate of the test rods prepared by the present invention is above 90%, which greatly reduces the manufacturing cost, avoids the waste of materials caused by casting defects, reduces the testing cost, can objectively reflect the intrinsic properties of titanium alloys and castings, and provide customers with more realistic reference data. The manufacturing method is easy to operate and reduces labor intensity.

Description

Technical Field

[0001] The invention belongs to the technical field of special alloy castings, and in particular relates to a titanium alloy test rod and a manufacturing method thereof. Background Art

[0002] Titanium and titanium alloys are not only light in weight (density is 4.5~4.8g / cm 3 ), high specific strength, high temperature resistance, corrosion resistance, antibacterial, and good biocompatibility, so it is widely used in aerospace, military industry, chemical industry, marine ships, biomedicine and daily necessities. The market demand for high-performance and lightweight titanium alloy products is increasing.

[0003] In the process of research and development and manufacturing of titanium alloys, it is an important means of verification to test the composition and mechanical properties of titanium alloys by making test bars. Titanium alloys have low superheat, poor fluidity, and are prone to forming hot spots. If the test bars are cast with the furnace, it is easy to have random pores, shrinkage cavities, shrinkage, and low-density inclusions. In addition, casting a single round bar or using a rod-type structure on the runner can easily lead to coarse grains and reduced mechanical properties, which cannot objectively reflect the intrinsic properties of titanium alloys. Summary of the invention

[0004] In view of the deficiencies in the prior art, in order to produce a qualified titanium alloy test rod to objectively reflect the intrinsic properties of the titanium alloy, the present invention provides a titanium alloy test rod and a manufacturing method.

[0005] The first aspect of the present invention is to provide a titanium alloy test rod, which is strip-shaped as a whole, and includes, from top to bottom, a first fixed section, a working section, a second fixed section, and a casting section that are integrally connected to each other; the thickness of the first fixed section and the second fixed section are both greater than the working section, and the first fixed section and the second fixed section are smoothly transitioned to the working section; the upper end of the casting section is the same thickness as the second fixed section, and the thickness gradually increases from top to bottom.

[0006] Furthermore, in the titanium alloy test rod, the heights of the first fixed section and the second fixed section are both smaller than the working section, and arc-shaped chamfers are formed at the connection between the working section and the first fixed section and at the connection between the working section and the second fixed section.

[0007] Furthermore, in the above-mentioned titanium alloy test rod, the cross-section of the casting section is an isosceles trapezoid that is narrow at the top and wide at the bottom.

[0008] The second aspect of the present invention is to provide a method for manufacturing a titanium alloy test rod, in which the titanium alloy test rod is cast in a centrifugal field, the titanium alloy test rod extends along the acceleration direction of the centrifugal field, and defects formed during the casting and solidification process tend to concentrate in the direction close to the center of the centrifugal field. After casting and solidification, a section of the titanium alloy test rod close to the center of the centrifugal field is cut off, and a section away from the center of the centrifugal field is retained, thereby obtaining a defect-free titanium alloy test rod.

[0009] Furthermore, the method for manufacturing the titanium alloy test rod comprises the following steps:

[0010] Step 1), making a corresponding mold according to the shape of the titanium alloy test bar;

[0011] Step 2), using the prepared mold to press the wax pattern, and then assembling the tree;

[0012] Step 3), manufacturing an oxide ceramic shell according to the composition tree, and then dewaxing, roasting, and washing the shell to obtain a shell that can be used for casting;

[0013] Step 4), casting is carried out in a centrifugal field, and after solidification, the half of the distal end of the centrifugal casting is cut off and heat treated to obtain a titanium alloy test rod.

[0014] Furthermore, in step 2) of the above-mentioned method for manufacturing a titanium alloy test rod, the assembled component has a pair of wax molds arranged in mirror symmetry.

[0015] Furthermore, in step 3) of the above-mentioned method for manufacturing the titanium alloy test rod, the surface layer of the mold shell is an yttrium oxide layer, the back layer is 1 corundum layer and 5 mullite sand layers, the temperature is 22±2 degrees, the humidity is 35~45%, and the drying time is >8h; the corundum layer is made by mixing corundum slurry and corundum sand, and the mullite sand layer is made by mixing mullite powder slurry and mullite sand.

[0016] Furthermore, in step 4) of the above-mentioned method for manufacturing a titanium alloy test rod, a solidified shell is formed between the titanium alloy molten casting liquid and the containing container, thereby preventing the containing container from contaminating the titanium alloy molten casting liquid.

[0017] Furthermore, in step 4) of the above-mentioned method for manufacturing the titanium alloy test rod, the titanium alloy raw material is heated to 650-850° C. in a vacuum environment and kept warm for 2 hours, thereby obtaining a titanium alloy molten casting liquid that can be used for casting.

[0018] Beneficial Effects

[0019] The test rod prepared by the present invention is not prone to defects such as pores, shrinkage cavities, shrinkage, low-density inclusions, etc., and the qualified rate is above 90%, which improves the yield rate and reduces the manufacturing cost. At the same time, it also avoids material waste caused by casting defects and reduces the detection cost.

[0020] The test rod prepared by the invention can objectively reflect the intrinsic properties of the titanium alloy and the casting and provide more authentic reference data.

[0021] The test rod manufacturing method provided by the invention is easy to operate and reduces labor intensity. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic structural diagram of the test rod of the present invention.

[0023] Figure 2 This is a schematic diagram of the structure of the tree assembly components obtained by the tree assembly of the present invention.

[0024] In the figure, 1 is the first fixed section, 2 is the working section, 3 is the second fixed section, and 4 is the casting section. DETAILED DESCRIPTION

[0025] The present invention is further illustrated by specific examples below. These examples are exemplary and are intended to illustrate the problem and explain the present invention, but are not intended to be limiting. Example

[0026] 1. Structure of titanium alloy test bar

[0027] Provide a Figure 1 The titanium alloy test rod of the structure shown is strip-shaped as a whole, and includes, from top to bottom, a first fixed section 1, a working section 2, a second fixed section 3, and a casting section 4 which are integrally connected to each other; the thickness of the first fixed section 1 and the second fixed section 3 are both greater than the working section 2, and the first fixed section 1 and the second fixed section 3 are smoothly transitioned to the working section 2; the upper end of the casting section 4 is as thick as the second fixed section 3, and the thickness gradually increases from top to bottom.

[0028] Furthermore, the heights of the first fixing section 1 and the second fixing section 3 are both smaller than the working section 2 , and arc-shaped chamfers are formed at the connection between the working section 2 and the first fixing section 1 and at the connection between the working section 2 and the second fixing section 3 .

[0029] Furthermore, the cross section of the casting section 4 is an isosceles trapezoid that is narrow at the top and wide at the bottom.

[0030] 2. Manufacturing method of titanium alloy test bar

[0031] Step 1), making a corresponding mold according to the shape of the titanium alloy test rod.

[0032] Step 2), using the prepared mold to press the wax pattern on a large press with medium temperature wax material to ensure the surface quality of the wax pattern, and then modifying the wax pattern and assembling the tree, such as Figure 2 shown.

[0033] Step 3), manufacture oxide ceramic shell, the surface and back layers of the shell are made of oxide as the molding material, so the shell has high strength and relatively low thermal conductivity, which is suitable for casting thin-walled castings with complex shapes. The surface layer is an yttrium oxide layer, the back layer is a layer of corundum (corundum slurry + corundum sand) and 5 layers of mullite sand (mullite powder slurry + mullite sand), temperature: 22 ± 2 degrees, humidity 35 ~ 45%, drying time > 8h), which improves the continuity and consistency of the process and improves production efficiency. Then, after dewaxing, roasting, and shell washing, a shell that can be used for casting is obtained.

[0034] Step 4) adopts the vacuum consumable electrode shell furnace melting and casting process. This furnace is developed on the basis of the vacuum consumable electrode arc furnace. It is a furnace type that combines smelting and centrifugal casting to cast special-shaped parts. Its biggest feature is that there is a thin layer of titanium alloy solid shell between the water-cooled copper crucible and the molten metal, namely the so-called shell. This shell of the same material is used as the lining of the crucible to form a molten pool to store titanium liquid, avoiding the contamination of the titanium alloy liquid by the crucible. After pouring, the layer of shell left in the crucible can continue to be used as the lining of the crucible. The casting system adopts centrifugal casting, such as Figure 2 As shown, the bottom of the test bar block is the feed port directly welded on the main runner. The liquid titanium alloy is thrown into the test bar block mold shell and continuously solidified. The residual gas in the mold shell is precipitated back to the end near the casting port. The thickness of the working section is relatively thin, and it is quickly cooled to form a fine grain area, and the mechanical properties are improved. After the casting is completed, the casting is cooled and taken out, the shell is cleaned, the casting block is cut out, and the half test bar block at the far end of the centrifugal casting is intercepted. The test bar is cut and machined, placed in a vacuum heat treatment furnace and heated to between 650 and 850 ° C and kept warm for 2 hours, cooled, and refined to obtain a qualified test bar.

[0035] The above embodiments are exemplary, and their purpose is to illustrate the technical concept and features of the present invention so that people familiar with the technology in this field can understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for manufacturing a titanium alloy test bar, characterized in that: The test rod is in the shape of a strip as a whole, and comprises, from top to bottom, a first fixing section (1), a working section (2), a second fixing section (3), and a casting section (4) which are integrally connected to each other; the thickness of the first fixing section (1) and the second fixing section (3) are both greater than the thickness of the working section (2), and the first fixing section (1) and the second fixing section (3) are both smoothly connected to the working section (2); the upper end of the casting section (4) is as thick as the second fixing section (3), and the thickness gradually increases from top to bottom; A titanium alloy test rod is cast in a centrifugal field, and extends along the acceleration direction of the centrifugal field. Defects formed during the casting and solidification process tend to concentrate in a direction close to the center of the centrifugal field. After casting and solidification, a section of the titanium alloy test rod close to the center of the centrifugal field is cut off, and a section away from the center of the centrifugal field is retained, thereby obtaining a titanium alloy test rod without defects.

2. The method for manufacturing a titanium alloy test bar according to claim 1, characterized in that: The following steps are involved: Step 1), making a corresponding mold according to the shape of the titanium alloy test bar; Step 2), using the prepared mold to press the wax pattern, and then assembling the tree; Step 3), manufacturing an oxide ceramic shell according to the composition tree, and then dewaxing, roasting, and washing the shell to obtain a shell that can be used for casting; Step 4), casting is carried out in a centrifugal field, and after solidification, the half of the distal end of the centrifugal casting is cut off and heat treated to obtain a titanium alloy test rod.

3. The method for manufacturing a titanium alloy test bar according to claim 2, characterized in that: In step 2), the tree assembly obtained has a pair of wax patterns arranged in mirror symmetry.

4. The method for manufacturing a titanium alloy test bar according to claim 2, characterized in that: In step 3), the surface layer of the mold shell is an yttrium oxide layer, the back layer is a corundum layer and 5 mullite sand layers, the temperature is 22±2 degrees, the humidity is 35~45%, and the drying time is>8h; the corundum layer is made by mixing corundum slurry and corundum sand, and the mullite sand layer is made by mixing mullite powder slurry and mullite sand.

5. The method for manufacturing a titanium alloy test bar according to claim 2, characterized in that: In step 4), a solidified shell is formed between the titanium alloy molten casting liquid and the container, thereby preventing the container from contaminating the titanium alloy molten casting liquid.

6. The method for manufacturing a titanium alloy test bar according to claim 2, characterized in that: In step 4), the titanium alloy raw material is heated to 650-850° C. in a vacuum environment and kept warm for 2 hours, thereby obtaining a titanium alloy molten casting liquid that can be used for casting.

7. The method for manufacturing a titanium alloy test bar according to claim 1, characterized in that: The heights of the first fixing section (1) and the second fixing section (3) are both smaller than the working section (2), and arc-shaped chamfers are formed at the connection between the working section (2) and the first fixing section (1) and at the connection between the working section (2) and the second fixing section (3).

8. The method for manufacturing a titanium alloy test bar according to claim 1, characterized in that: The cross section of the casting section (4) is an isosceles trapezoid that is narrow at the top and wide at the bottom.

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