Titanium flaw detection method---eddy current flaw detection

Eddy current testing is an alternating magnetic field generated by an alternating current acting on the conductive material to be tested, inducing eddy currents. If there is a defect in the material, it will interfere with the generated eddy currents, i.e. create an interference signal.

By detecting its interference signal with an eddy current flaw detector, the state of the defect can be known. There are many factors that affect the eddy current, that is to say, the eddy current contains abundant signals, and these signals are related to many factors of the material. How to separate the useful signals from the many signals is a difficult problem for the current eddy current researchers. , some progress has been made over the years, and some problems can be solved under certain conditions, but it is far from meeting the requirements of the scene and needs to be vigorously developed.

The remarkable feature of eddy current flaw detection is that it can work on conductive materials, not necessarily ferromagnetic materials, but the effect on ferromagnetic materials is poor. Secondly, the surface finish, flatness, and edge of the workpiece to be tested have a great influence on eddy current testing, so eddy current testing is often used for non-ferromagnetic workpieces such as copper pipes with regular shapes and smooth surfaces. Grade 2 Pure Titanium Bar

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Industrial Expansion Titanium Screw Usage

To install ceiling fans, chandeliers on ceilings, or install hanging cabinets on concrete walls, expanded titanium metric screw are a very suitable part. The hanging force is large, and the installation is also very simple by mastering the small skills of installing small screws.

This kind of screw has many forms and specifications, but the tomb is composed of three parts: the trunk, the screw and the nut. The installation method is as follows:

(1) Generally, if you hit the wall and hang it horizontally, it is not a problem to lift more than 100 pounds of screws with a diameter of 6 mm. Determine the location on the wall and drill a hole the same diameter as the screw, the depth of which is the length of the screw's trunk.

(2) Hit the trunk with the screw into the hole of the wall, use the screw to pass through the cabinet to be lifted, and tighten the nut. When the screw is tightened, the gap of the trunk is forced to open and stretch around, becoming an inverted shape. , so the hanging force is very large.

In addition, there is a plastic expansion screw whose hanging force is not as large as that of metal, but it is simpler and more convenient to use. Generally, a mirror frame is installed on the wall, and this kind of screw is enough to be safe.

(1) Punch a hole the same size as the screw, and the depth is the length of the screw.

(2) Install the plastic screw trunk in the hole.

(3) Because the main part of the opening is solid, when you screw a wood screw of the same size as the inner diameter of the trunk, the lower part of the trunk is forced to stretch out to form a wedge shape, which can increase the hanging. force effect.

What are the differences between seamless titanium alloy pipes and welded titanium alloy pipes

Titanium tubes are generally divided into two types, one is extruded type called seamless titanium tube; the other is welded type called welded titanium tube. Welded titanium alloy pipe, also known as welded pipe, is a titanium alloy pipe made of titanium plate or titanium strip after bending and forming. Titanium Alloy Rectangular Tube has a short production process, high production efficiency, and unlimited pipe length, suitable for specifications, varieties and grades more singular.

1. Welded titanium alloy tube is a hollow square-section titanium-titanium alloy tube, also known as hollow cold-formed titanium. Formed titanium with square cross-section shape scale made by high frequency welding. In addition to the thickening of the wall thickness of the thick-walled titanium alloy tube, its corner size and edge straightness reach or even exceed the level of resistance welded cold-formed titanium alloy tubes, and the size of the R angle is usually 2 to 3 times the wall thickness. Between. It can also produce the R angle titanium alloy tube of the size required by the customer according to the needs of the customer;

2. Titanium alloy pipe Seamless titanium alloy pipe is a long titanium material with a hollow section and no joints around it. It is a titanium alloy pipe formed by kneading a seamless pipe through the four sides of the mold. The titanium alloy pipe has a hollow section. Cross-section, many used as pipelines for transporting fluids. Mainly used in liquid transportation, hydraulic supports, mechanical layout, medium and low pressure. .

How does the relative density and porosity of the target affect the coating quality?

The relative density of the target is the ratio of the actual density of the target to the theoretical density, the theoretical density of the single-component target is the crystalline density, and the theoretical density of the alloy or mixture target is determined by the theoretical density of each component and its content in the alloy or mixture. proportion is calculated. The thermal spraying Tungsten Sputtering Target has a loose and porous structure, high oxygen content (even if it is vacuum sprayed, it is difficult to avoid the generation of oxides and nitrides in the alloy target), the surface is gray, lacks metallic luster, and the adsorbed impurities and moisture are the main The source of pollution, which hinders the rapid acquisition of high vacuum, easily leads to discharge during the sputtering process, and even burns the target.

At the same time, the instantaneous high temperature on the sputtering surface of the target can easily cause the loose particles to fall off, contaminate the glass surface, and affect the coating quality. There are clear regulations for the point-like release on the surface of coated glass. The regulations are shown in Table 1. The higher the relative density, the faster the film formation rate and the more stable the sputtering process. According to the difference of the target preparation process, the relative density of the casting target should be guaranteed to be above 98%, and the powder metallurgy target should be guaranteed to be above 97% to meet the production requirements. Therefore, it is necessary to strictly control the density of the target material to reduce the occurrence of slag removal. The spraying target has low density and low preparation cost. When the relative density can be guaranteed to be more than 90%, it generally does not affect the use. The SiA1 targets currently used are all spraying targets.

In addition to the density, if the target is abnormal in the production process, such as large particles falling off or shrinking cavities due to heat, more pores (internal defects) will be formed, and larger inside the target (casting target>2mm, spraying target> 0.5mm) or denser holes will cause discharge due to charge concentration, affecting use. Targets with low density and pores are prone to chipping during subsequent processing, handling or installation. The target material with high relative density and few pores has good thermal conductivity, and the heat on the surface of the sputtering target material is easily and quickly transferred to the inner surface of the target material or the cooling water in the liner, and the heat dissipation is good, thus ensuring the stability of the film formation process.

Titanium fittings are heat treated to remove residues

When the hydrogen content in the titanium pipe fitting is too large, the impact toughness and notched tensile strength will drop sharply due to embrittlement, so it is generally stipulated that the hydrogen content in the titanium pipe should not exceed 0.015%. In order to reduce the amount of hydrogen absorption, the parts should be free of fingerprints, rolling mill marks, grease and other residues before heat treatment, and there is no moisture in the heat treatment furnace. If the hydrogen content of titanium pipes exceeds the allowable value, it must be removed by vacuum annealing.

When the temperature does not exceed 540 degrees, the oxide film of the titanium pipe will not be significantly thickened, but at a higher heat treatment temperature, the oxidation rate will rapidly accelerate, and at the same time, the internal diffusion layer of the oxidized material is a pollution layer. The oxygen contamination layer has a high brittleness ratio that leads to cracks and damage on the surface of the part. There are mechanical processing methods, or chemical methods such as pickling, chemical milling, etc. for deoxidizing pollution layers. During heat treatment, the heating time should be shortened as much as possible under the premise of ensuring heat treatment. It can also be carried out in a vacuum furnace or an inert gas heating furnace. . The contamination of titanium pipe fittings when heated in an air furnace should be appropriately avoided or mitigated.

Application areas of titanium alloy capillaries

The capillary titanium alloy tube is atomized by pyrogen and the granules in the molten state are severely attacked at a high speed to the surface of the cleaned and unsmooth substrate to produce the required coating. The moment the particles hit the surface of the substrate hard, it will be deformed, and with the help of the "England" effect, a coating with a lamellar structure is produced. With many "overlapping continuous accumulation" of plastic deformation particles, the fusion between particles should be mostly mechanical equipment, and there must be a certain number of holes. In addition, if painting is carried out in the air, there is likely to be metal in the coating. Mixed oxides.

Titanium tubes are mainly used to make aero-engine compressor components, followed by rockets, cruise missiles and structural parts of high-speed airports. In the middle and late 1960s, titanium and aluminum alloys have been used in general industrial production to make electric grades for electrolytic industrial production, coolers in power plants, electric heaters for crude oil refining and seawater desalination equipment and their air pollution. Manipulating equipment, etc. ASTM F136 6Al-4V ELI Titanium Bar and aluminum alloys have become a corrosion-resistant structural raw material. In addition, it is also used to produce hydrogen storage raw materials and shape memory alloys.

Capillary titanium alloy tube is a new key structural raw material used in aerospace industry production. Its proportion, compressive strength and application temperature are close to the middle of aluminum and steel, but it has high specific strength and excellent sea surface corrosion resistance and low temperature characteristics.