Method for selecting rolling temperature of industrial titanium plate and titanium alloy plate

Hot rolling of titanium alloy materials should generally be carried out in the B or a+P phase region. The hot rolling temperature is 50~100℃ higher than the forging temperature line, and the plate with a thickness of 2~5mm can use the warm rolling process, and the thinner plate can be cold rolled. During cold rolling, the cold rolling deformation between two anneals is 15% to 60%. Grade 7 Titanium Sheet are metals with phase transformation. The selection of slab heating temperature must consider the process plasticity, deformation resistance of the a+β phase region and the effect of the getter layer on the surface plasticity of the rolled piece at high temperature. The process plasticity of the B-phase region is better than that of the a-phase region, and the deformation resistance is lower, but the heating temperature is high, which increases the depth of the getter layer, and serious cracks will occur on the surface during uneven deformation.

The hot rolling of the titanium plate is carried out in the phase zone, which can ensure good process plasticity, and the total processing rate of the billet can reach 90%. Pure titanium TA1, TA2 and TA3 are below the phase transition point, generally heated at 850~870℃, while TC4 should be selected at the upper limit of the a+B phase transition point or by superplastic forming process (heated at 1000~950℃). TC1, TC2, TC3, etc., the hot rolling process plasticity is slightly worse, the thicker the slab, the more serious the edge cracking and the more serious surface cracking due to uneven deformation during rolling. Although Grade 9 Ti-3Al-2.5V Titanium Plate has good oxidation resistance, it has a high degree of alloying and high deformation resistance. Therefore, selecting the heating temperature of TA7 thick slab in the B phase region is more conducive to deformation, which can make full use of the plasticity of the alloy and reduce the number of tempering.

Advantages of hot die forging and conventional forging of titanium alloys

Like isothermal forging, hot die forging of titanium alloy processing technology is also a promising precision forging process. The difference is that the die temperature of hot die forging is higher than that of ordinary forging, but lower than that of isothermal forging. A typical hot die forging die temperature is 110-225°C lower than the billet temperature. Compared with isothermal forging, the reduction of mold temperature allows a wider selection of mold materials, but the ability to form very thin and complex shape forgings is slightly worse.

Compared with conventional forging, hot die forging has the following advantages:

(1) Reduce the material consumption of titanium forged disc. During hot die forging, the chilling of the die contacting the blank and the work hardening of the material are reduced, and the forgeability of the material is improved, so the forgings are allowed to have a smaller fillet radius and a smaller draft. Slope and small forging allowance, thus greatly reducing the quality of the forging. For example, a Ti-6Al-4V alloy structural part has a mass of 28kg, the mass of the forging produced by the conventional forging process is 154kg, and the mass of the forging produced by the hot die forging process is 109kg, and the difference between the two methods is 45kg.

(2) Reduce the number of forging operations and improve the working capacity of the press. During hot die forging, the temperature of the die is higher and the temperature drop of the billet is less. Conventional Titanium Eye Bolt requires two, three or more fires to form forgings, hot die forging Just one time, as many as two fires can be completed. And due to hot die forging, the deformation resistance of the metal is relatively low, which relatively increases the working capacity of the equipment.

(3) Reduce the amount of machining of forgings Because the produced forgings are close to the weight and contour size of the parts, the amount of material removed in machining is reduced compared to forgings produced by conventional forging.

(4) The uniformity of the product is better. During the forging process, the temperature gradient is greatly reduced, and the uneven deformation caused by the temperature gradient is easily reduced. Therefore, the uniformity and consistency of the structure and performance of the product are better than those produced by conventional forging. , but not as good as forgings produced by isothermal forging.

During hot die forging, although the billet has a temperature drop, it is still in the forging temperature range, and the increase in deformation resistance is not as sharp as in conventional forging. The strain rate used in hot die forging varies in the range of 0.05 to 0.2s-1. If the strain rate is too low, the billet temperature may decrease.

In the hot die forging of titanium alloys, the forging heating temperature, strain rate, microstructure of the preform and holding time are extremely important factors, which play a decisive role in the dimensional accuracy and microstructure of the formed parts. Typically lower strain rates and longer dwell times increase the likelihood of precision forming. The microstructure of the preform has a direct impact on the flow stress and superplasticity of the material, especially the post-forging structure. It is impossible to completely eliminate the defects and grain inhomogeneity in the raw material by isothermal forging or hot die forging.

At present, the use of hot die forging process for titanium alloys and superalloys mainly depends on the total cost of forgings or the needs of product uniformity and consistency. The trend in this process is to use conventional forging preforms, followed by final isothermal or hot die forging.

Performance characteristics and specific applications of titanium alloy materials

The outstanding performance characteristic of titanium alloy material is that its own strength is very high, it can withstand the pressure of 1500 MPa, and the density is only 4.5g/cm3. Secondly, titanium alloy materials have good thermal stability at 300~500 ° C, and their strength is greater than 10 times or even more than common aluminum alloy materials. Thirdly, AMS 4928 Titanium Alloy Bar have strong corrosion resistance, and they are more excellent than stainless steel materials in terms of corrosion resistance, acid corrosion and stress corrosion resistance when exposed to high air humidity and alkaline medium for a long time. The chemical activity of titanium alloy is relatively prominent. After contacting with the material elements such as O2, CO2 and H in the air, it can form a strong chemical reaction. When heated to 600 °C, it will show a violent oxygen absorption characteristic, resulting in a hardness Very high hardened layer. Gr5 Ti-6Al-4V Titanium Foil has poor thermal conductivity, and its thermal conductivity is also relatively low, only 1/5 of iron and 1/4 of nickel. The thermal conductivity of titanium alloy materials is even lower, which is only 1/2 of the thermal conductivity of pure titanium.

Characteristics of titanium alloy materials such as titanium rods and titanium alloy rods and types of heat treatment processes for rods

Titanium is very stable in the air at room temperature. When heated to 400-550 °C, a firm oxide film is formed on the surface, which plays a protective role to prevent further oxidation. Titanium has a strong ability to absorb oxygen, nitrogen, and hydrogen. These gases are impurities that are very harmful to metal titanium, and even a small content (0.01% to 0.005%) can seriously affect its mechanical properties. Among the titanium compounds, titanium dioxide (TiO2) has practical value. TiO2 is inert to the human body, non-toxic, and has a series of excellent optical properties. TiO2 is opaque, with high gloss and whiteness, high refractive index and scattering power, strong covering power, and good dispersibility. The pigment made is a white powder, commonly known as titanium dioxide, which is widely used. The appearance of the machined titanium round rod is very similar to that of steel, with a density of 4.51 g/cm3, which is less than 60% of that of steel, and is a metal element with low density in refractory metals. The mechanical properties of titanium, commonly known as mechanical properties, are closely related to purity. High-purity titanium has excellent machinability, good elongation, and area shrinkage, but low strength and is not suitable for structural materials. Industrial pure titanium contains an appropriate amount of impurities, has high strength and plasticity, and is suitable for making structural materials.

Titanium alloys are divided into low-strength and high-plasticity, medium-strength, and high-strength, ranging from 200 (low-strength) to 1300 (high-strength) MPa, but in general, titanium alloys can be regarded as high-strength alloys. They are stronger than aluminum alloys, which are considered medium-strength, and can completely replace certain types of steel in strength. Some titanium alloys can still maintain good strength at 600°C compared to aluminum alloys whose strength decreases rapidly at temperatures above 150°C. Dense metal titanium is highly valued by the aviation industry due to its lightweight, higher strength than aluminum alloys, and its ability to maintain higher strength than aluminum at high temperatures. Considering that the density of titanium is 57% of that of steel, its specific strength (strength/weight ratio or strength/density ratio) is high, and its anti-corrosion, anti-oxidation, and anti-fatigue capabilities are all strong, and 3/4 of titanium alloys are used as 1/4 of the structural materials represented by aviation structural alloys are mainly used as corrosion-resistant alloys. Titanium alloy has high strength and low density, good mechanical properties, good toughness, and corrosion resistance. In addition, the process performance of titanium alloy is poor, cutting is difficult, and it is very easy to absorb impurities such as hydrogen, oxygen, nitrogen, and carbon during hot processing. There is also poor wear resistance and a complex production process. The industrial production of titanium started in 1948. The need for the development of the aviation industry makes the titanium industry develop at an average annual growth rate of about 8%. At present, the annual output of titanium alloy processing materials in the world has reached more than 40,000 tons, and there are nearly 30 kinds of titanium alloy grades. The widely used titanium alloys are Ti-6Al-4V(TC4)'Ti-5Al-2.5Sn(TA7) and industrial pure titanium (TA1, TA2, and TA3).

There are three heat treatment processes for astm b348 titanium rod and titanium alloy rods:

1. Solution treatment and aging:

The purpose is to increase its strength, alpha titanium alloys and stable beta titanium alloys cannot be strengthened by heat treatment, and are only annealed in production. α+β titanium alloys and metastable β titanium alloys containing a small amount of α phase can be further strengthened by solution treatment and aging.

2. Stress relief annealing:

The purpose is to eliminate or reduce the residual stress generated during processing. Prevent chemical attacks and reduce deformation in some corrosive environments.

3. Complete annealing:

The purpose is to obtain good toughness, improve processing properties, facilitate reprocessing and improve dimensional and organizational stability.

Characteristics of titanium alloys for construction

Titanium alloys are widely used in various fields because of their high strength, good corrosion resistance, and high heat resistance. Many countries in the world have recognized the importance of titanium alloy materials, have carried out research and development on them one after another, and have been practically applied by titanium alloy manufacturers.

Grade 5 Ti-6Al-4V Titanium Sheet is also a building material. It is mainly used in the exterior wall decoration of buildings, roof surface decoration, waterproofing, etc. It is also used in building column decoration, monuments, signs, house numbers, railings, pipes, corrosion protection, etc. covered, etc. For example, in 1997, the Guggenheim Museum in Bilbao, Spain used titanium metal panels as the exterior decoration of building.

Titanium alloy material is an alloy composed of titanium and other elements. It was developed in the 1950s and was mainly used in the aviation field. It has the characteristics of high strength, good corrosion resistance, and high heat resistance. Use at a temperature of 600°C.

ASTM F136 6Al-4V ELI Titanium Bar has a satisfactory natural luster, sparkle, different colors after surface oxidation, and excellent corrosion resistance. Because of these characteristics, they were later used as building materials in buildings. However, the price is relatively expensive, and it is generally used in public buildings with relatively high requirements.

Performance characteristics of titanium flanges for chemical ships and aviation

Titanium flange is a non-ferrous or titanium alloy connecting pipe structure. The titanium flange has holes, and the two flanges are closely connected. The flanges are sealed with gaskets. Flanged pipe parts refer to pipe fittings with flanges (joints or joints).

Threaded or welded joints are available. The flange joint consists of a pair of flanges, a gasket, and several bolts and nuts. The gasket is placed between the two flanged glands. After tightening the nut, when the specific pressure of the gasket surface reaches a certain value, the sealing surface is filled unevenly and the connection is tight.

According to the structure, it can be divided into titanium flange, butt welding titanium flange, threaded titanium flange, blind titanium alloy flange, etc.

Product Specifications: Various specifications are produced according to flange standards, or non-standard flanges can be produced according to the drawings provided by customers.

Manufacturing method: free forging, die forging, precision forging, welding.

Inspection method: radiographic inspection, dyeing, flaw detection, hydrostatic test, etc. can be carried out according to customer needs.

The cladding rolling process will bring changes to the production of titanium alloy sheets

The production of domestic titanium alloy sheets is still mostly rolled by the single-piece method. Due to the poor low-temperature plasticity of titanium alloys and large cold deformation work hardening, it is extremely difficult to produce thin plates by the single-piece method. In order to make the rolling process go smoothly and reduce the temperature drop of the metal during the forging process, especially to reduce the chill on the surface of the billet, the die for forging titanium alloy needs to be preheated. Otherwise, the metal temperature drop and surface chill will make the metal not fill the mold groove well and may cause many cracks. Die preheating systems for titanium alloy forging are usually detachable, but sometimes a heating device mounted on the press is also used. Detachable die heating systems are usually gas heaters that slowly heat the die to the desired temperature range before the modules are assembled into the forging equipment. The heating device solidified on the press usually adopts induction heating or resistance heating. With the expansion of the market, the new technology of superplastic forming-diffusion joining of titanium alloy sheet has been widely used.

According to statistics, in the production of TC4 titanium plate, the invisible loss caused by alkaline pickling and grinding is as high as about 30%, the comprehensive yield is only about 35%, and the production cycle is long and the performance is unstable. The deformation rate of the cold rolling degree is not more than 25%, and it requires multiple cold rolling, intermediate annealing, and alkali pickling, and process defects such as cracks, edge cracks, slag removal, and cratering are prone to occur during rolling. Production process of titanium alloy plate (below 1.0mm), titanium alloy cross rolling and beta thermal process, self-developed stack rolling and clad rolling process, titanium and titanium alloy warm rolling technology, self-developed atmosphere protection controllable Cooling gravity creep correction technology and other key technologies for a series of flow rectification processes. In the test of the new production process of TC4 sheet, TC4 sheet with thickness of 0.6mm has been produced by cladding and rolling process, and it has been put into mass production.