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What are the classifications of die forging processes?

Die forging processes can be classified according to the following principles:According to the flow conditions of metal deformation, it can be divided into open die forging and closed die forging;According to the temperature of the blank during die forging, it can be divided into hot forging, warm forging and cold forging.According to the combination form of die forging process, it can be divided into single groove die forging and multi-groove die forging, continuous die forging and combined die forging.Common joint die forging are: free forging hammer billet - a die forging hammer pre-forging and final forging; Roll forging machine billet - crank press pre-forging and final forging; Pre-forging and final forging with hammer or press; Electrically sensitive roughing-one press final forging; Hammer sensitive coarse and punching - ring rolling machine reaming, etc.In addition, according to the forging equipment, it can be divided into hammer die forging, flat forging machine die forging, crank press die forging, screw press and hydraulic press die forging, etc.

What are the precautions for titanium alloy?

Titanium has a tendency to fill grinding wheel, so it is difficult to wear titanium belt. Before grinding, the higher temperature rise on the interface between metal and grinding wheel makes the grinding surface produce higher residual stress, and the surface finish is not ideal.These difficulties can be largely resolved by:(1) Choose the right grinding wheel, such as silicon carbide grinding wheel, sand particle size is medium (60-80), the hardness is medium (J~M), the surface velocity is 700~1200m/min. Oxidized (alumina powder or corundum) grinding wheels should be used at lower speeds, e.g. 550~600min. Medium granularity is also required.(2) Use lower grinding wheel speed and feed speed; Due to the low speed of grinding wheel, less spark is produced.(3) with buffer or cutting liquid cooling agent cooling, with ceramic bond and chlorinated or chlorinated cutting oil, you can obtain good results. No matter what type of cooling, with ceramic bond and chlorinated or chlorinated cutting oil, you can obtain good results. No matter what type of cooling is used, it should be well filtered to eliminate "fishtail" stains caused by titanium particle recycling.(4) Titanium sparks may catch fire in oil mist, but oil immersion can reduce this risk. Rustproof nitrite can completely eliminate fire hazard according to water bath.However, even optimal grinding conditions can reduce the fatigue performance of the workpiece.

What are the chemical properties of titanium ?

Metal communities are highly reductive at high temperatures, combining with oxygen, carbon, gas, and many other elements, and capturing oxygen from some metal vaporizers (such as alumina). At room temperature, the needle combines with oxygen to generate a layer of very thin and dense oxide film. This layer of oxygen film does not react with most of the strong acid and alkali at room temperature, including the king of acid aqua regia, it only reacts with reoxyacid, hot concentrated hydrochloric acid, concentrated sulfuric acid, so titanium reflects the corrosion resistance.It may react with many elements and compounds at high temperatures. Depending on how they react, these elements can be divided into four groups:The first class: halogen and oxygen group elements, covalent and ionic bonds with titanium compounds;The second type: transition elements, hydrogen, wrinkle, build, carbon and ammonia elements, and titanium to form intermetallic compounds and finite solid solutions;The third category: vauxite, bell, vanadium, Ming, anti elements, and titanium to form infinite solid Body:The fourth category: natural gases, alkali metals, alkaline earth metals, rare earth elements (except resistance), steel, let, etc., do not react with titanium or basically do not react.

What is rolling? What is the rolling principle?

Rolling is by virtue of the friction of the upper and lower rotating rolls, the metal material is dragged between the rolls, and at the same time rely on the roll to exert pressure for continuous compression deformation, get the required shape of the processing method. In other words, it makes use of the friction between the rolled piece and the roll to attract the rolled piece to the roll for continuous rolling, so that the cross section area of the rolled piece decreases and the length increases.Usually in the rolling process, the two rolls are the main drive, and the diameter is equal, the roller surface circumference speed is the same; The speed of rolled parts is balanced at the roller and the roller. The rolled parts are not affected by any external force except by the roll. The contact friction of the upper and lower roller surfaces is the same, and the deformation along the high direction (i.e. thickness) and wide direction of the rolled section is completely symmetric with the flow of metal particles. The performance of rolled pieces is even. Rolling process is a commonly used process to produce titanium and titanium alloy plates, bars, pipes and profiles, etc.

What are the classifications of surface treatment techniques for titanium?

Titanium surface treatment technology is mainly to improve the surface function of titanium, in order to meet the special requirements of the material, the main categories are:Surface purification, namely to improve the surface cleanliness of titanium and titanium alloy.Corrosion resistance surface treatment, namely to improve the corrosion resistance of titanium alloy surface.Wear resistance surface treatment, namely to improve the wear resistance of titanium and titanium alloy surface.Artificial surface treatment, that is, to improve the surface color of titanium and titanium alloy, or to meet some special needs of customers.

What is titanium welding? What are the common welding methods?

A method of atomically bonding a titanium workpiece by heating or pressurizing it, or a combination of both, with or without filler material.Titanium and titanium alloy commonly used welding methods are: melt welding, brazing, solid bonding, mechanical bonding, bonding and so on. Among them, melt welding is the most widely used, which can be divided into arc welding, electron beam welding, resistance welding and so on. The most commonly used is emotional gas (mainly hydrogen) protection welding, also known as hydrogen arc welding.The weldability of titanium material depends on the chemical activity and physical properties of the material itself. At room temperature, the surface of titanium has thin and dense oxide film, stable performance. Sharp increase with the increase of temperature, the activity of titanium, when welding temperature higher than 600 ℃, the density of the oxide film was damaged, gas can through the internal diffusion to metal oxide film loose, and hydrogen, oxygen, nitrogen and other elements to produce violent chemical reaction, these elements exist in interstitial impurity in titanium, decreased its welded joint performance especially in plastic. The presence of hydrogen is also often the cause of porosity and cold crack in the weld. See Figure 13-1 for the classification of titanium welding methods. 

How magnetic is titanium? What is it for?

Titanium itself is not magnetic, and titanium alloys without iron are not magnetic either, so it can effectively avoid magnetic interference. Used for submarine housing, does not cause mine explosion. Besides used in national defense, air force, home to weapons manufacture, are widely used in railway engineering, communications, aerospace, aviation, high-tech laboratories, hospitals, scanning, X-ray, magnetic resonance imaging (fmri), electrocardiogram (ecg), cathode ray tube), medicine, nuclear industry, nuclear magnetic resonance (NMR), high magnetic spectrometer, tesla magnets, outdoor work, pier construction, diving, chemical industry, fire protection, water desalination, Shipbuilding, offshore oil and gas platforms, salt industry, etc.

What is rolling? What is the rolling principle?

Rolling is a processing method that uses the friction force of the upper and lower rotating rollers to drag the metal material into the rolling room, and at the same time relies on the roller to exert continuous compression deformation to obtain the desired shape. In other words, it makes use of the friction between the rolled piece and the roll to induce the rolling piece to be rolled continuously, so that the cross section area of the rolled piece decreases and the length increases.Usually in the rolling process, the two rolls are the main drive, and the diameter is equal, the roller surface circumference speed is the same; The speed of rolled parts is balanced at the silver inlet and the roll outlet. The rolled parts are not affected by any external force except by the roll. The contact friction of the upper and lower roller surfaces is the same, and the deformation along the high direction (i.e. thickness) and wide direction of  the rolled section is completely symmetric with the flow of metal particles. The performance of rolled pieces is even. Rolling process is a common process to produce titanium and titanium alloy plates, bars, pipes and profiles.

Where can the niobium metal material be used?

iron industry• About 85% to 90% of the world's niobium is used in steel production in the form of ferroniobium. Only adding 0.03% to 0.05% of niobium to the steel can increase the yield strength of the steel by more than 30%. Niobium can also achieve the dispersion and distribution of precipitates by inducing precipitation and controlling the cooling rate, and adjust the toughness level of steel in a wide range. Therefore, adding niobium to the steel can not only increase the strength of the steel, but also improve the toughness, high temperature oxidation resistance and corrosion resistance of the steel, reduce the brittle transition temperature of the steel, and make the steel have good welding and forming properties.• Superconducting material industry• Certain niobium compounds and alloys have high superconducting transition temperatures, so they are widely used in the manufacture of various industrial superconductors, such as superconducting generators, accelerator high-power magnets, superconducting magnetic energy storage, and nuclear magnetic resonance imaging equipment Wait. At present, the most important superconductor materials are niobium-titanium and niobium-tin, which are widely used in magnetic resonance imaging apparatus for medical diagnosis and nuclear magnetic resonance apparatus for spectral line (analysis).• Aerospace industry• The aerospace industry is the main application field of high-purity niobium, which is mainly used to produce rockets and spacecraft engines and heat-resistant parts. The heat-strength alloy of niobium and tantalum has good heat-strength performance, heat resistance and processing performance, and is widely used in the manufacture of aero-engine parts and gas turbine blades. Almost all jet fighter engines in the United States use niobium alloy for the hot parts.• Atomic Energy Industry• Niobium has good thermal conductivity, high melting point, good corrosion resistance, and low neutron capture cross section. It is a very suitable material for atomic energy reactors. The main uses of niobium in the nuclear industry include: nuclear fuel cladding materials, nuclear fuel alloys, and structural materials for heat exchangers in nuclear reactors.• electronics industry• Niobate ceramics can be used to make capacitors. Compound single crystals such as lithium niobate and potassium niobate are new types of crystals for optoelectronics and electronics. They have good piezoelectric, pyroelectric and optical properties and are widely used in infrared and laser technology. And the electronics industry. In addition, niobium has a high melting point, strong ability to emit electrons, and has the ability to get gas. It can be used to make electron tubes and other electric vacuum devices.• medical field• Niobium has good resistance to physiological corrosion and biocompatibility, does not interact with various liquid substances in the human body, and hardly damages the body tissues of organisms. It can adapt to any sterilization method, so it is often used Used in the manufacture of bone plates, skull screws, dental implants, surgical appliances, etc.In the chemical industry, niobium is a high-quality acid and liquid metal corrosion-resistant material, which can be used to make digesters, heaters, coolers, etc. In addition, niobic acid is also an important catalyst.• Niobium is also used in the foundry industry. Its main function is to form hard carbides (good for wear resistance) and change the morphology and size of graphite sheets, so it is often used in the manufacture of automobile cylinder heads, piston rings and brake pads. Wait. In addition, niobium is sometimes used in commemorative coins along with gold and silver.• Niobium helps to increase the light transmission performance of the lens, so it is also used in the manufacture of lenses in the optical industry.• Niobium can also be applied to the lighting industry. For example, the alloy of niobium and 1% zirconium can be used to make precision brackets for high-efficiency and high-strength sodium vapor street lights, so that these small parts have high thermal strength, excellent formability and resistance to sodium vapor corrosion. performance.

What are the characteristics and application fields of tantalum?

Tantalum has a series of excellent properties such as high melting point, low vapor pressure, good cold working performance, high chemical stability, strong resistance to liquid metal corrosion, and large surface oxide film dielectric constant. Therefore, tantalum has important applications in high-tech fields such as electronics, metallurgy, steel, chemical, cemented carbide, atomic energy, superconducting technology, automotive electronics, aerospace, medical and health, and scientific research.50%-70% of tantalum in the world is used in the production of tantalum capacitors in the form of capacitor-grade tantalum powder and tantalum wire. Since the surface of tantalum can form a dense and stable amorphous oxide film with high dielectric strength, it is easy to accurately and conveniently control the anodic oxidation process of the capacitor. At the same time, the sintered tantalum powder can obtain a large surface area in a small volume, so tantalum Capacitors have high capacitance, low leakage current, low equivalent series resistance, good high and low temperature characteristics, long service life, excellent comprehensive performance, and other capacitors are difficult to match. It is widely used in communications (switches, mobile phones, pagers, Fax machines, etc.), computers, automobiles, household and office electrical appliances, instrumentation, aerospace, national defense and military industry and other industrial and technological sectors. Therefore, tantalum is an extremely versatile functional material.

What are the mechanical properties of titanium at low temperature?

Titanium and titanium alloys still maintain certain mechanical properties at low and ultra-low temperatures. As the temperature decreases, the strength of titanium and titanium alloys increases, while the ductility gradually decreases. Many annealed titanium alloys have sufficient ductility and fracture toughness at a temperature of 195.5℃. Ti-5al-2.5sn with extremely low interstitial elements can be used at a temperature of 252.7℃. The ratio of notched tensile strength to non-notched tensile strength is 0.95~1.15 at a temperature of 25.7℃.Liquid oxygen, liquid hydrogen and liquid gas are important propellants in missiles and space devices. The low temperature properties of materials used to make cryogenic gas vessels and cryogenic structures are very important. When the microstructure is equiaxed and the content of interstitial elements (oxygen, nitrogen, hydrogen, etc.) is very low, the elongation of titanium alloy is still above 5%. Most titanium alloys have low elongation at -252.7℃, while ti-6Al-4V has elongation as high as 12%.

what are problems and precautions that are easy to get in the cold rolling process of titanium pipe?

Titanium pipes are prone to surface defects, especially internal surface cracks and folds, during the cold rolling process. The mechanical properties of pure titanium largely depend on the content of interstitial elements, especially the oxygen content. The reduced oxygen content material has good plasticity and good processing performance, but this method alone does not eliminate defects such as cracks and folds on the inner surface of the pipe on a large scale, and it is difficult to ensure the strength of the pipe. Therefore, it is necessary to analyze the rolling deformation process of thick-walled pipes with different oxygen content to find out the causes of defects. For titanium, due to the effect of work hardening, there is a positive correlation between the degree of deformation and its strength and hardness. Therefore, studying the microhardness and metallographic structure on the deformed section can indirectly display different parts on the section. The size of the degree of deformation, so as to study and analyze the rolling process. The microstructures near the outer wall and near the inner wall of the titanium tube rolled in each pass. The deformed fibrous structure near the inner wall of the titanium pipe after each pass rolling is finer than that of the outer layer. The hardness value of the inner wall point in the hardness curve during the rolling process is greater than that of the outer wall point, which is basically the same, which also reflects the thick-walled pipe from the side. The phenomenon of uneven deformation along the thickness direction on the cross-section during the deformation process. 1. During the deformation process of thick-walled titanium pipe, the curve, especially the inner hole curve, should be gentle, and the feed amount should be small. 2. From the analysis of the hardness distribution curve, the titanium pipe has uneven deformation along the wall thickness direction during the deformation process, and the increase in oxygen content will make this uneven phenomenon more complicated. In the case of a large deformation rate (35% more) and a low oxygen content, the deformation of the interrupted surface of the thick-walled tube during the rolling process will gradually become uniform. However, when the oxygen content is high, even if the pipe rolling meets the condition of large deformation rate, the deformation on the section is difficult to be uniform.

What should be pay attention to in the process of cutting titanium alloy?

(1) Due to the small elastic modulus of titanium alloy, the workpiece in the process of clamping deformation and stress deformation, will reduce the machining accuracy of the workpiece; Workpiece installation clamping force should not be too large, if necessary, can increase the auxiliary support.(2) If the gas containing cutting fluid is used, the cutting process will decompose and release hydrogen at high temperature, which will be absorbed by titanium to cause hydrogen embrittlement, and may also cause high temperature stress corrosion cracking of titanium alloy.(3) When the chloride in the cutting fluid is used, it may decompose or volatilize toxic gases. Safety protection measures should be taken when using, otherwise it should not be used. After cutting, the parts should be thoroughly cleaned with gas-free cleaning agent in time to remove chlorine residues.(4) It is forbidden to use lead or zinc-based alloy made of work, fixture and titanium alloy contact, copper, tin, pot and their alloys are also prohibited to use.(5) All work, fixtures or other devices in contact with titanium alloy must be clean; Cleaned titanium alloy parts should be protected from grease or fingerprint contamination, which may later cause salt (sodium chloride) stress corrosion.(6) in general, when cutting titanium alloy, there is no danger of ignition, only in the micro cutting, cutting small chips have ignition combustion phenomenon. In order to avoid fire, in addition to pouring a large amount of cutting fluid, but also to prevent chip accumulation on the machine tool, the tool with blunt immediately replace, or reduce the cutting speed, increase the feed to increase chip thickness. In case of fire, talcum powder, limestone powder, dry sand and other fire extinguishing equipment should be used to extinguish the fire. Carbon tetrachloride and carbon dioxide fire extinguishers are strictly prohibited, and watering is not allowed, because water can accelerate the combustion and even lead to hydrogen explosion.

What is the basic principle of titanium cutting?

The general principle of titanium cutting is: low cutting speed, large feed, lubrication,Cooling.(1) the lower cutting speed should be used, generally speaking, should be 50% lower than the cutting speed of steel parts with the same hardness.(2) the use of large feed, in the cutting process do not stop the tool, when the tool to go back through the workpiece should be the first back tool.(3) The cutting edge should be properly and sharp, otherwise the tool is easy to wear.(4) Use sufficient cutting fluid (lubricating coolant) to cool, remove heat from the blade and wash away chips.(5) The use of hard alloy cutter head or high speed steel tool.(6) The use of rigid machinery and tools.