Traditional processing methods of titanium and titanium alloys

The traditional methods of titanium and titanium alloy processing mainly include ingot metallurgy (or plastic processing), casting and powder metallurgy. The process method of titanium and titanium alloy ingot metallurgy is to melt sponge titanium, intermediate alloy or pure metal into ingot, and then process it into Gr5 Ti-6Al-4V Titanium Foil material by cold and hot. Ingot processing methods include forging, rolling, extrusion, drawing, stamping and spinning, among which forging is the indispensable, most basic and most important method, followed by rolling, and a small part of titanium is extruded Spinning is a supplementary method for drawing materials, and the use is the least. These five titanium ingot processing methods have their own characteristics and are complementary. In the processing of ASTM B861 25*1.2mm Titanium Tube For Chemical and titanium alloy materials, if one method is not enough, it can be processed into finished or semi-finished titanium alloys of various shapes and specifications through several methods. The plastic processing of titanium alloy has the characteristics of large deformation resistance, low plasticity, high yield strength and tensile strength ratio, large springback, sensitivity to notches, easy adhesion to the mold during deformation, and easy oxidation when heated at high temperatures. The plastic processing ratio of titanium alloy Steel, copper and aluminum are difficult.

Several current surface treatment methods for titanium building materials in the world

According to the data, there are roughly six treatment methods for the surface of titanium materials. Now we will introduce and analyze them one by one:

1. Sandblasting method

The surface of the titanium material is sandblasted with a certain particle size shot blasting to make the surface of the titanium material rough. The surface reflectivity is reduced, and the disadvantage is that it is easy to deform the plate when processing the thin plate.

2. Pickling method

The surface is treated in the acid solution of HF + HNO3 to make the surface of the plate present the original color of Grade 16 Ti-0.5Pd Titanium Tube. The disadvantage is that the color is single, and the surface color consistency is easily damaged during use, which is relatively unsuitable for the decoration industry.

3. Rolling embossing method

After the surface of the roll is pretreated, the titanium plate is smoothed, so that the surface of the titanium plate produces regular unevenness. The key to this method is the surface treatment of the rolls. The existing domestic treatment methods are sandblasting, electric spark treatment, and laser treatment.

4. Anodizing method

The color tone control of this method uses an anodizing device to give a rated voltage, and as the voltage rises, the color changes. This method can be divided into direct current electrolytic anodizing method, alternating current electrolytic anodizing method, laser irradiation multicolor treatment in solution, thick film anodizing method and chemical oxidation method.

When the DC electrolysis setting voltage is a certain multiple of the AC electrolysis setting voltage, the same color can be obtained. According to the increase in voltage, the color changes as follows: gold, red purple, cyan, yellow, purple, cyan, cyan, green, yellow-green.

To carry out the colorful coloring treatment of the titanium material, the covering method and the anodizing treatment can be combined, but the process is complicated. The method of laser irradiation in the solution can be used to carry out the colorful treatment of Gr7 Ti-0.2Pd Titanium Plate. The method is to irradiate the titanium surface with laser in the solution. As the anodic oxidation and laser irradiation are carried out at the same time, the part irradiated by the laser is etched and the oxide film becomes thinner. During the secondary anodization of the laser-irradiated part, the resistance of the etched part is reduced and the current is large. The thickness of the oxide film formed during the formation of the oxide film is different from that of the part that is not irradiated by the laser, and the color is different. Repeat this many times to obtain Multi-colored titanium surface.

5. Rolling embossing method + pickling

It adopts the advantages of rolling method and pickling method, so that the titanium surface with regular unevenness reveals the metal color that titanium metal should have, and it can give people a noble and solemn feeling in application.

6. Sandblasting + coloring method

This method reduces the reflectivity of the surface of the board, and at the same time obtains the required surface color, which is also popular in the decoration industry.

What are the advantages of induction melting technology for titanium alloy forgings?

At present, the smelting method widely used in China's industry is the vacuum consumable electrode arc smelting method. Although it can effectively ensure that the alloy liquid has a certain degree of superheat and a more accurate alloy melt composition, this method has extremely high requirements for the quality of the raw electrode, and the surface area of ​​the molten pool is large and the depth is small, resulting in high vapor pressure elements (such as A1 The volatilization loss of the element) is very large, which is unfavorable for controlling the alloy composition.

The water-cooled copper crucible induction smelting method is to place a copper crucible that is split and cooled by water under an induction electromagnetic field for smelting, which can maximize the advantages of the induction smelting method. Between the water-cooled copper crucible and the metal melt, there is a solid shell layer produced by the solidification of the titanium flange melt, the so-called condensed shell. At this time, the crucible lining is equivalent to being made of molten metal, that is, the inner surface of the crucible has the same composition as the molten metal, which prevents the crucible from contaminating the molten metal. With the increase in the number of cold crucible combinations and the input power of the power supply, the strong magnetic field promotes the rapid melting of the charge and produces a strong stirring effect, so that the temperature and composition of the metal melt are uniform, and a consistent degree of superheat can be obtained. Due to the complex composition of the new titanium bar and TiAl compound alloy, the allowable deviation of the alloy element content is small, it is difficult to meet the requirements of the alloy composition by the common arc melting method of titanium alloy rod. Water-cooled crucible induction condensed shell melting is particularly suitable for this work. The molten alloy composition is uniform, and the superheat of the alloy liquid with the interstitial element content is appropriate, which meets the requirements of static and centrifugal casting.

Machining Process and Special Tool Design of Titanium Alloy Inner Cavity Cylindrical Surface

At present, the requirements of aerospace products for processing accuracy are continuously increasing, and the number of overall structural parts in the aerospace field is continuously increasing. High-precision thin-walled cavity parts are more and more widely used in the aerospace product industry. The machining accuracy control of the Grade 2 Titanium Tube electrode, especially the machining accuracy control of the servo system, is directly related to the requirements of many performance indicators of the weapon system. Titanium alloy blanks are generally used for such parts, and the material removal rate can reach 85%. At the same time, a significant production feature of this kind of parts is the variety, small batches, and even single-piece production. This structural feature and production method have determined that its manufacturing technology has always been in an unstable state, and processing and manufacturing have always been faced with difficulties such as long processing cycles, high processing costs, and difficult control of processing accuracy.

The material of the spherical ring frame is titanium alloy tc4, which is a single piece and small batch production. These parts are precision machined parts. The external dimension of the part is sφ108mm, and the wall thickness is 4mm. It is a thin-walled and difficult-to-machine material part, and has high requirements for shape and dimensional accuracy. Due to the integral cutting and forming, it is easy to deform during the processing, the material cutting performance is poor, and the part structure is also poor, which brings great difficulties to the processing. Therefore, choosing a reasonable processing method and the correct tool is the key to ensuring processing quality.

The spherical ring frame material is titanium alloy tc4, which is characterized by: poor thermal conductivity of titanium alloy is a metal material with poor thermal conductivity. During cutting, the contact area between chips and the rake face is small, which is particularly easy to cause thermal deformation of thin-walled parts. Tungsten Sputtering Target alloy has low elastic modulus and large elastic deformation. The modulus of elasticity of titanium alloy is 1078mpa (about 1/2 of steel). When cutting, the workpiece near the flank face has a large springback, resulting in a large contact area between the machined face and the flank face. As a result, the geometric dimensions and accuracy of the workpiece are poor, the surface roughness increases, and tool wear increases. Titanium alloy has a higher affinity and higher cutting temperature. During cutting, the titanium chips and the surface to be cut are occluded with the tool material, resulting in serious tool jamming, which is easy to cause tool jamming and wear. Titanium alloy has strong high temperature chemical activity. When the temperature exceeds 600, there is an interstitial solid solution containing oxygen and nitrogen. After the gas is absorbed, the surface hardness of the titanium alloy is obviously improved, which has a strong wear effect on the knife. Therefore, titanium alloy processing tools are required to have high strength, high toughness and high red hardness.

Development Trend of TC4 Titanium Alloy Heat Treatment Process

In view of the above-mentioned status quo of TC4 titanium alloy in today's heat treatment process, in its future development trend, the following points are summarized:

First, the two-state structure and Widmanstatten structure in TC4 titanium alloy have both advantages and disadvantages. Therefore, in future research, the defects of the two should be compensated for, so that the mechanical properties of TC4 titanium alloy can be obtained. Effective enhancement.

Second, because air cooling can improve the comprehensiveness of the mechanical properties, in the solution treatment process, when the cooling rate is studied, the air cooling should be studied emphatically. After the TC4 titanium alloy is air-cooled , Its own strength and hardness are effectively improved, so as to effectively enhance the mechanical properties of TC4 titanium alloy.

Third, the size of the α of the secondary phase depends on the effective temperature. Therefore, relevant scientific researchers should be aware of how to control the size of the α of the secondary phase in the actual effect process. Control the comprehensive mechanical properties of the TC4 titanium alloy to achieve the purpose of effectively enhancing the mechanical properties of the TC4 titanium alloy.

Fourth, because the aging time and aging temperature of TC4 titanium alloy have similar changes in mechanical properties, relevant scientific researchers should conduct in-depth research on the aging time of titanium welded tubing.

Fifth, since the equipment of cryogenic treatment process is relatively expensive, the specific mechanism is not yet understood, and it has not been widely used at this stage. Therefore, the future research on cryogenic treatment equipment mainly focuses on how to get the cost. Effective reduction, only when the cost of the layer is reduced, can it be applied to various fields, which will help promote the development of Pickling Titanium Wire in the cryogenic treatment process.

What are the polishing methods for titanium rods and titanium alloys?

What are the polishing methods for titanium rods and titanium alloys? (1) Fine grinding. That is, the surface of titanium rods and titanium-containing alloy castings is lapped using conventional various types of emery rubber wheels. The problem that needs to be paid attention to during grinding is still not to cause the casting to generate heat, not to cause grinding damage on the surface of the casting, and to make the entire surface smooth.

(2) Barrel grinding method. The so-called barrel grinding method is to put the processed castings, abrasives, water and additives into the barrel-type grinding tank. The grinding barrel generates rotation and vibration, causing friction between the mixture of abrasives and the processed castings, and grinds the surface of the castings smoothly. ,smooth.

It is characterized by no dust pollution, low labor intensity, and no heat generation in the conventional grinding process. At present, Japan has commercialized barrel grinders and abrasive materials used for grinding Gr23 Ti-6Al-4V ELI Titanium Sheet and titanium-containing alloy castings, other metal castings and plastics.

(3) Mechanical polishing method. Use different specifications of soft cloth wheels or black brushes, dipped in titanium and titanium-containing alloy special polishing paste to polish the surface of titanium and Grade 36 Titanium Wire. When polishing titanium castings, it is necessary to completely clear the contamination layer on the surface of the casting and no new grinding and hardening layer occurs, which will not achieve the desired polishing effect.

High-speed and light-pressure methods are still used for polishing. The author has also tried using green polishing paste to polish titanium and titanium-containing alloy castings, and achieved a relatively ideal polishing effect. The polished titanium and titanium-containing alloy castings cannot be washed immediately. The surface oxide film must be completely formed before washing, otherwise the surface will darken.

Titanium alloy industry chain

The industrial chain of the titanium industry can be simply divided into two, one is the industrial chain of non-ferrous metals: titanium ore→sponge titanium→titanium ingot→titanium material; the other is the industrial chain of chemical industry: titanium ore→titanium dioxide. These two industrial chains are closely related to each other in the upstream, but are independent of each other in the midstream and downstream.

The titanium non-ferrous metal industry chain can be divided into three major parts from top to bottom:

1) The upstream includes titanium ore resources such as ilmenite and rutile, as well as artificial rutile, titanium slag and Grade 1 Titanium Tube tetrachloride processed from ilmenite;

2) The middle stream is mainly divided into two parts: one is the reduction of titanium tetrachloride to generate sponge titanium; the other is the melting and casting of sponge titanium into titanium ingots, and then the preparation of titanium round rod processing materials including forgings, bars, plates, pipes, wires, wires, etc. ；

3) The downstream is mainly to further process titanium blanks according to the requirements of specific applications such as aerospace, petrochemical, nuclear power, ships, desalination, automobiles, sports medicine and other fields;