Suggest to collect eight items of stainless steel welding and pay attention to nine problems

Share some of the eight precautions for stainless steel welding, let’s take a look!

1. Chrome stainless steel has certain corrosion resistance (oxidizing acid, organic acid, cavitation), heat resistance, and wear resistance. It is usually used for power plants, the chemical industry, petroleum, and other equipment and materials. The weldability of chrome stainless steel is poor, so attention should be paid to the welding process, heat treatment conditions, etc.

2. Chromium 13 stainless steel has high hardenability after welding and is easy to crack. If the same type of chromium stainless steel electrodes (G202, G207) are used for welding, preheating above 300 ℃ and slow cooling treatment at about 700 ℃ after welding must be carried out. If the weldment cannot undergo post-weld heat treatment, chromium-nickel stainless steel electrodes (A107, A207) shall be used.

3. In order to improve the corrosion resistance and weldability of chrome 17 stainless steel, appropriate stability elements such as Ti, Nb, and Mo are added, and the weldability is better than that of chrome 13 stainless steel. When the same type of chromium stainless steel electrodes (G302, G307) is used, the preheating above 200 ℃ and the tempering after welding at about 800 ℃ shall be carried out. If the weldment cannot be heat treated, chromium-nickel stainless steel electrodes (A107, A207) shall be used.

4. During the welding of chromium-nickel stainless steel, carbides are precipitated by repeated heating, reducing corrosion resistance and mechanical properties.

5. Chromium nickel stainless steel electrode has good corrosion resistance and oxidation resistance and is widely used in the chemical industry, fertilizer, petroleum, and medical machinery manufacturing.

6. Chromium nickel stainless steel coating includes titanium calcium type and low hydrogen type. Titanium calcium type can be used for AC and DC welding, but the penetration is shallow during AC welding, and it is easy to redden, so DC power supply should be used as far as possible. Diameters 4.0 and below can be used for all position weldments, and 5.0 and above can be used for flat welding and flat fillet welding.

7. The welding rod shall be kept dry during use. The titanium calcium type shall be dried at 150 ℃ for 1 hour, and the low hydrogen type shall be dried at 200-250 ℃ for 1 hour (repeated drying is not allowed, otherwise the coating is easy to crack and flake) to prevent the coating of the welding rod from sticking oil and other dirt, so as not to increase the carbon content of the weld and affect the quality of the weldment.

8. In order to prevent eye corrosion due to heating, the welding current should not be too large, about 20% less than that of carbon steel electrode, the arc should not be too long, and the interlayer should be cooled quickly, so it is better to narrow the weld bead.

9 major problems in stainless steel welding

1. What are stainless steel and stainless acid-resistant steel?

Answer: The content of the main added element “chromium” in the metal materials (nickel, molybdenum and other elements that need to be added) can make the steel in the passivation state and stainless steel. Acid-resistant steel refers to steel that is resistant to corrosion in strongly corrosive media such as acid, alkali, and salt.

2. What is austenitic stainless steel? What are the commonly used brands?

Answer: Austenitic stainless steel is the most widely used and has the most varieties. For example:

18-8 series: 0Cr19Ni9 (304) 0Cr18Ni8 (308)

18-12 series: 00Cr18Ni12Mo2Ti (316L)

25-13 series: 0Cr25Ni13 (309)

< 4 > 25-20 series: 0Cr25Ni20, etc

3. Why is it difficult to weld stainless steel?

Answer: The main process difficulties are:

The stainless steel material has a strong thermal sensitivity, staying at 450-850 ℃ for a long time, and the corrosion resistance of the weld and heat-affected zone is seriously reduced.

Hot cracks are easy to occur.

Poor protection and severe high-temperature oxidation.

The linear expansion coefficient is large, resulting in large welding deformation.

4. Why should effective process measures be taken for welding austenitic stainless steel?

Answer: General process measures include:

Welding materials shall be strictly selected according to the chemical composition of the base metal.

< 2 > Low current, Rapid welding; Small wire energy, reduce heat input.

The welding wire and electrode with a fine diameter shall not swing and shall be welded in multiple layers and passes.

< 4 > The weld and heat-affected zone are forced to cool, reducing the residence time of 450-850 ℃.

< 5 > Argon protection at the back of the TIG weld.

The weld in contact with the corrosive medium shall be welded finally.

(7) Passivation treatment of weld and heat affected zone.

5. Why should 25-13 series welding wires and electrodes be used for welding austenitic stainless steel, carbon steel, and low alloy steel (dissimilar steel welding)?

Answer: For welding dissimilar steel welded joints between austenitic stainless steel and carbon steel, low-alloy steel, 25-13 series welding wires (309, 309L) and welding rods (A312, A307, etc.) must be used as weld deposit metal. If other stainless steel welding materials are used, the martensite structure will be generated on the fusion line of one side of carbon steel and low alloy steel, which will cause cold cracks.

6. Why should 98% Ar+2% O2 shielding gas be used for solid stainless steel welding wire?

Answer: If pure argon gas is used for MIG welding with the solid stainless steel welding wire, the surface tension of the molten pool is large, and the weld formation is poor, showing a “hunchback” weld shape. Add 1-2% oxygen to reduce the surface tension of the molten pool and make the weld formation smooth and beautiful.

7. Why is the surface of the MIG weld of solid stainless steel welding wire blackened?

Answer: The MIG welding speed of solid stainless steel welding wire is fast (30-60cm/min). The shielding gas nozzle has run to the front end molten pool area. The weld is still in a hot and hot state. The weld is oxidized by air, and the surface generates oxides. The weld is blackened. Acid pickling and passivation can remove the black skin and restore the original surface color of stainless steel.

8. Why does the solid stainless steel welding wire need a pulsed power supply to achieve jet transfer and splash-free welding?

Answer: During MIG welding with the solid stainless steel welding wire, φ 1.2 Welding wire, when the current I ≥ 260-280A, the jet transfer can be realized; If the value is less than this value, the droplet is short-circuited, with a large spatter, and generally cannot be used. Only when the MIG power supply with a pulse is used and the pulse current is greater than 300A, the pulsed droplet transfer under 80-260A welding current can be realized without spatter welding.

9. Why is the flux-cored stainless steel wire protected by CO2 gas? No pulsed power supply?

Answer: For the commonly used flux-cored stainless steel welding wires (such as 308, 309, etc.), the flux formula in the welding wire is developed according to the chemical and metallurgical reaction of welding under CO2 gas protection, so it cannot be used for MAG or MIG welding; The pulsed arc welding power source shall not be used.

Titanium rod manufacturers introduce methods to identify fake and inferior products!

Many titanium rod manufacturers want to buy high-quality titanium rods when they buy titanium rods, but how to distinguish the quality of titanium rods? titanium rod manufacturers teach us how to make titanium rods good or bad from many aspects and angles.

1. The appearance of counterfeit and inferior titanium rods often has pockmarks.

The pockmarked surface is due to the serious wear and tear of the rolling groove, which leads to the irregular and uneven surface of the titanium material. Because manufacturers of counterfeit and inferior titanium rods seek to make profits, there are often overruns in grooving and rolling.

2. False and inferior titanium rods are easy to scratch. The reason is that the manufacturers of fake and inferior titanium rods have poor equipment, which is prone to burrs and scratches on the surface of titanium materials. Deep scratches reduce the strength of titanium.

3. The horizontal ribs of fake and inferior titanium rods are thin and low, and often appear to be full and dissatisfied. The reason is that in order to achieve a large negative tolerance, the reduction in the first few passes of the finished product is too large, the iron shape is too small, and the hole shape is not full.

4. False and inferior titanium rods are prone to folding.

Folding is a variety of fold lines formed on the surface of titanium rods, and this defect often runs through the longitudinal direction of the entire product. The reason for the folding is that the counterfeit and inferior manufacturers pursue high efficiency, and the reduction is too large, resulting in ears. Folding occurs during the next rolling process. The folded product will crack after bending, and the strength of the titanium material will be greatly reduced.

5. Fake and inferior titanium rods are prone to scarring on the surface.

There are two reasons: (1) The raw materials of fake and inferior titanium rods are uneven and have many impurities. (2) The guides and guards of fake and inferior material manufacturers are poorly equipped and easily stick to titanium. These impurities are prone to scarring after biting the roll.

6. Cracks are easy to occur on the surface of fake and inferior materials. The reason is that the billet is adobe, and the adobe has many pores. During the cooling process, the adobe suffers from thermal stress, cracks occur, and there are cracks after rolling.

7. False and inferior titanium rods have no metallic luster and are light red or similar in color to pig iron. There are two reasons for this. Two, its blank is adobe. The rolling temperature of fake and inferior materials is not standardized, and their titanium temperature is measured visually, so they cannot be rolled according to the regular austenite region, and the function of titanium materials is naturally unqualified.

8. The cross-section of fake and inferior titanium rods is elliptical. The reason is that in order to save materials, the reduction amount of the first two passes of the finished roll is too large. specification.

The above is all the content shared by the titanium rod manufacturer, I hope you can like it, welcome your consultation!

What are the methods to prevent stainless steel solid round rods from rusting?

From the product name, it seems that stainless steel will not rust, but it is not. We need to know the specific methods to avoid rust from stainless steel products. In fact, this has a lot to do with the nickel element in stainless steel solid round rods. The following and The editor of the same metal will look at a few key points to avoid stainless steel rusting, for your reference only.

1. In polluted air (such as an atmosphere containing a large amount of sulfide, carbon oxide, and nitrogen oxide), when it encounters condensed water, it will form sulfuric acid, nitric acid, and acetic acid liquid points, causing chemical corrosion.

2. Organic juices (such as vegetables, noodle soup, sputum, etc.) adhere to the surface of stainless steel screws. In the presence of water and oxygen, organic acids are formed, and organic acids will corrode the metal surface for a long time.

3. The attachment of dust or heterogeneous metal particles, in the humid air, the attachment and the condensed water of the stainless steel screw connect the two into a micro-battery, which triggers an electrochemical reaction and destroys the protective film, which is called electricity. chemical corrosion.

4. The surface of the stainless steel bar adheres to acid, alkali, and salt substances (such as alkaline water and lime water splashed on the wall for decoration), causing local corrosion.

Main characteristics and uses of aluminum brass

Special brass is formed by adding aluminum, silicon, manganese, lead, tin, and other elements into a copper-zinc alloy. Such as lead brass, tin brass, aluminum brass, silicon brass, manganese brass, etc.

Lead brass has excellent cutting performance and good wear resistance and is widely used to make clock parts, bearing shells, and bushes by casting.

Tin brass has good corrosion resistance and is widely used in the manufacture of marine parts.

Aluminum in aluminum brass can improve the strength and hardness of brass, and improve the corrosion resistance in the atmosphere. Aluminum brass is used to make corrosion-resistant parts.

Silicon in silicon brass can improve the mechanical properties, wear resistance, and corrosion resistance of copper. Silicon brass is mainly used to make parts for seagoing ships and chemical machinery.

What are the main characteristics of aluminum brass?

Aluminum brass has strong wear resistance. It has high strength, high hardness, and strong chemical corrosion resistance. There are also outstanding mechanical properties of cutting. Seamless copper tube drawn from aluminum brass is soft and wear-resistant. Aluminum brass seamless tubes can be used for heat exchangers and condensers, cryogenic pipelines, and submarine transport tubes. Manufacture sheet, bar, pipe, casting parts, etc. It contains 62%~68% copper and has strong plasticity. It is used to manufacture pressure-resistant equipment.

What are the uses of aluminum brass?

Aluminum in aluminum brass can improve the strength and hardness of brass, and improve the corrosion resistance in the atmosphere. Aluminum brass is used to make corrosion-resistant parts.

What are the components of aluminum brass?

Copper: 66.0 ~ 68.0

Sn: ≤ 0.2

Zinc: allowance

Lead Pb: ≤ 0.5

Phosphorus P: ≤ 0.02

Aluminum: 2.0 ~ 3.0

Fe: ≤ 0.6

Manganese Mn: ≤ 0.5

Antimony Sb: ≤ 0.05

Note: ≤ 1.5 (impurities)

What are the applications of aluminum brass?

The main alloy composition of aluminum brass is Cu Zn Al. In order to improve the strength, corrosion resistance, wear resistance, etc. of aluminum brass in practical application, elements such as As, Mn, Fe, Ni, etc. are often added to the alloy, thus greatly improving the comprehensive properties of the material. Due to the aluminum zinc equivalent coefficient 6 β The phase trend is large, and the strengthening effect is good. When the aluminum content increases γ Phase. Although the hardness of the alloy is increased, the plasticity is sharply reduced. In aluminum brass, the ionization tendency of the aluminum surface is greater than that of zinc. The dense and hard aluminum oxide film is preferentially formed to prevent the alloy from further oxidation and improve the corrosion resistance to gas, and solution, especially high-speed seawater.

Welding and testing of titanium alloys

Weldability Analysis
Due to the high affinity of titanium alloys with O2, N2, and H2, the presence of these gases in the joints will make the joints brittle and reduce the impact performance, plasticity and toughness of titanium alloy welded joints. The presence of hydrogen in titanium alloys can cause delayed cracking in the heat-affected zone. When the amount of oxygen and nitrogen in the weld is high, the weld or heat-affected zone will also crack under the action of large welding stress, and the crack is also a delayed crack. Therefore, inert gas (or vacuum chamber) protection is very necessary. Due to the high cost of using a vacuum chamber, the method of inert gas protection is generally used. The main protective gases are helium and argon. Since the price of helium is higher than that of argon, generally speaking, for welding joints and heat-affected zones of titanium alloys that are not specially required, high-purity argon can be used for protection to prevent oxidation.

Most titanium alloys can be welded using oxyacetylene welding, and all titanium alloys can be welded using solid state welding methods (eg TIG, MIG, plasma arc, laser and electron beam welding). In fact, the tendency of titanium alloy welded joints to crack is much smaller than that of black metals (such as iron alloys, nickel alloys).

Although titanium alloys have such good properties and other excellent welding characteristics, some engineers still think that the welding of titanium alloys is quite difficult, mainly because the welding of titanium alloys has very high requirements for gas protection, and generally only very professional staff can Ensure that the gas protection meets the requirements. In fact, many welding methods can be used to weld titanium alloys.

Since the N2, O2 and carbonaceous substances in the air introduced during the welding process make the molten welded joint of the titanium alloy brittle, the area to be welded must be cleaned and protected with inert gas. The welding material is basically selected according to the characteristics of the material to be welded. The weldability of titanium alloys is generally evaluated based on the ductility and strength of the welded joint.

Laser welding titanium plate
The current application trend of laser welding of titanium alloys is more and more extensive, laser welding has small deformation, high production efficiency, and the degree of automation is higher than electron beam and TIG. Compared with electron beam welding, laser welding does not require complex equipment such as a vacuum chamber, so laser welding is more practical, and laser welding can be directly welded in different welding states.

Due to the high power of the CO2 laser, 25kW/h can be used to penetrate a titanium plate with a thickness of 20mm at one time. Nd:YAG lasers make YAG welding more flexible due to the ability to use optical fibers for energy transfer, but the penetration depth is limited due to the low power. It is easy to generate spatter during laser welding, which makes the surface unclean, and special care must be taken when post-weld treatment is not possible.

Post weld inspection
Visual inspection of titanium alloy welding parts is mainly to evaluate the quality of gas shielding. When the surface is silvery white, it means that the gas protection is very good; and when the surface is light yellow or dark yellow, it means that the titanium alloy is slightly polluted, but it is still acceptable; the surface is dark blue, which means that the pollution is serious, but due to the use of Different working conditions, some can be used; the surface is light blue, the pollution is serious, and it is almost impossible to use; when the surface is gray-blue or gray, the pollution is very serious and cannot be used; the same surface is white, the pollution is very serious, unavailable.

Color detection method
Hardness testing and eddy current testing can be used to detect whether the joint contains impurities. Since the properties of the joint will change when impurities are contained, the hardness and resistivity of the joint will be significantly higher when impurities are contained. The portable hand-held hardness tester can be used to test the hardness of weldments in situ. The application of this technology can easily detect the quality of welding. Under normal circumstances, the occurrence of welding cracks in titanium alloys is relatively small. However, cracks sometimes occur in the weld or due to inclusions. At this time, defects can be found by coloring inspection, and this method also has a certain effect on porosity. It must be noted that the colorant must be cleaned before proceeding with welding.

What are the properties of copper alloy casting?

We all know that copper alloy casting has high hardness and good wear resistance and is widely used, so what are the functions of copper alloy casting? What are the functions of copper alloy casting for us today?
1. High hardness, excellent wear resistance, not easy to cause seizure, good casting function and cutting production function, and excellent corrosion resistance in the atmosphere and fresh water.
2. Good corrosion resistance, wear resistance and cutting production function, good casting function, high fineness of castings, and good air tightness
3. Corrosion resistance, especially for dilute sulfuric acid and fatty acid.
4. Good wear resistance and corrosion resistance, easy to manufacture, good casting function, and air tightness.
5. Copper alloy casting has good mechanical properties, corrosion resistance in the atmosphere, freshwater, and seawater, good casting performance, fine arrangement, good air tightness, good wear resistance, and can be welded.
6. It has good mechanical function and wears resistance, can be heat treated, has good corrosion resistance and oxidation resistance at high temperatures, and has good corrosion resistance in the atmosphere, freshwater, and seawater, and can be welded. crisp.
7. Copper alloy casting has good sliding properties and self-lubricating function under the condition of lack of lubricant and water-based lubricant, easy cutting, poor casting function, and good corrosion resistance to dilute sulfuric acid.
8. Copper alloy casting has good casting performance and wears resistance, good cutting performance, good corrosion resistance, and has a tendency to stress in seawater.

The New Egyptian capital represents a bold vision for smart cities

Egypt’s ambitious new administrative capital is a large-scale infrastructure project on the edge of Cairo that will be crowned by Africa’s tallest skyscraper.

Halfway between the historic city of Cairo and the Gulf of Suez sits the as-yet-unnamed new administrative and financial capital (NAC) of Egypt. Still, under construction, the new metropolis already rises impressively from what was formerly a 700km2 expanse of desert 45km to the east of the Nile.

Cairo’s 20 million residents already make it one of the most crowded cities in the world, with the greater region’s population expected to double over the next 20-30 years. The new city is expected to ease congestion and boost economic development as part of the Egypt Vision 2030 program.

Designed to accommodate the country’s main government departments and ministries, as well as foreign embassies, the NAC will house a population of 6.5 million once completed.

A steel-built oasis

Planned to support 21 residential districts and 25 ‘dedicated’ districts, the city will boast a sprawling central park with artificial lakes and a steel and concrete composite-built ‘green river’ that will run through the NAC, mimicking the path of the Nile through Cairo.

The city will also feature 2,000 educational institutions, more than 600 hospitals, and clinics, a technology, and innovation park as well as a huge theme park that will be four times the size of Disneyland.

The city will play host to the new national stadium, a 93,000-seater which will be the second largest in Africa once completed. The stadium roof, which will be supported by a high-strength steel truss frame and steel suspension cables, is designed to resemble the ceremonial headdress of Queen Nefertiti.

The NAC’s business district is home to Africa’s tallest tower – The Iconic

The valley of the skyscrapers

At its heart will be the NAC’s downtown, a newly developed cluster of skyscrapers that will be home to the city’s business district. Looming over the skyline is the city’s pinnacle, the glittering Iconic Tower.

Standing 394m tall over 78 floors and two basement levels, the Iconic is Africa’s tallest tower. Inspired by the 3,000-year-old Obelisk of Luxor, the building comprises 40 floors of offices, and 10 high-end apartments, with another 30 for a five-star hotel with a 74th-floor observation deck that offers unparalleled views of the new cityscape.

The tower was constructed by the China State Construction Engineering Company, which had the challenge of laying the supertall structure’s foundations into the basalt rock which lies underneath the NAC.

The Iconic Tower is formed of a composite steel structure grounded on a reinforced concrete raft that sits directly on the rock surface. Safely supporting the full weight of 78 floors requires 4,600 tonnes of high-strength steel reinforcement and the new tower’s foundations are rock solid.

Making connections

Connecting and powering an entirely new city is a massive undertaking, with huge engineering works needed to provide sewers, power cables, and roads to the NAC’s desert location.

90 square kilometers of solar energy farms slated for development in the nearby desert allowed planners to take advantage of the high levels of solar activity the region experiences, with the aim to provide up to 35% of the city’s energy needs.

450km of high-strength steel rail will be laid and operational by 2023, with an expected 1,750km expansion later connecting the new capital with the city of Aswan

Egypt has also teamed up with Siemens to deliver a high-speed rail line that will extend from El Alamein on Egypt’s Mediterranean coast through the NAC to Ain Sokhna on the country’s Red Sea coastline.

The 450km of high-strength steel rail will be laid and operational by 2023, with an expected 1,750km expansion later connecting the new capital with the city of Aswan on the edge of Lake Nasser in Egypt’s south.

Egypt’s new capital city is founded on the skills of the design and engineering teams that make infrastructure projects like this possible. Those teams in turn needed materials they could rely on to realize their ambition – an innovative steel-built city towering above the desert.

The difference between 316L stainless steel and 2205 duplex stainless steel

316L stainless steel is widely used in the chemical industry because of its excellent corrosion resistance. 316L stainless steel is also a derivative of 18-8 type austenitic stainless steel, with 2~3% molybdenum added.Nitrogen is added to 2205 duplex stainless steel to improve local corrosion resistance. Its solid solution structure accounts for about half of ferrite and austenite. Generally, the minimum phase content needs to reach 30%, so it has ferrite. Performance characteristics of bulk and austenitic stainless steels.

From the above point of view, 316L stainless steel and 2205 duplex stainless steel are two different stainless steel materials. The question is, which stainless steel has more advantages? What about the downside? The following ZTE Yide Xiaobian will tell you about it.

The differences between 316L stainless steel and 2205 duplex stainless steel are as follows:

1. The yield strength of 2205 duplex stainless steel is more than double that of 316L stainless steel, and it has enough plastic toughness for forming. The wall thickness of the pressure vessel made of 2205 duplex stainless steel is 30-50% lower than that of 316L stainless steel, which is conducive to reducing costs.

2. 2205 duplex stainless steel has excellent resistance to stress corrosion cracking, especially in the marine environment containing chloride ions, stress corrosion is a prominent problem that is difficult to solve for austenitic stainless steel including 316L stainless steel.

3. In many media, the corrosion resistance of 2205 duplex stainless steel is better than that of ordinary 316L stainless steel, because duplex stainless steel has extremely high corrosion resistance, such as acetic acid, formic acid, etc. It can even replace austenitic stainless steel and even corrosion resistance alloy. However, it is still necessary to choose 2205 duplex stainless steel or 316L stainless steel according to environmental requirements and cost.

4. It has high strength and good local corrosion resistance, and its wear resistance and corrosion fatigue properties are better than 316L stainless steel.

5. The linear expansion coefficient of it is lower than that of 316L stainless steel, and it is close to carbon steel. It is suitable for carbon steel connections and has important engineering significance.

6. Whether under dynamic or static load conditions, 2205 duplex stainless steel has a higher energy absorption capacity than 316L stainless steel, which has obvious advantages and practical application value for structural parts or pipelines to cope with sudden shocks, explosions, etc.

Having said so much about their differences, it seems to have more advantages than 316L stainless steel, but does it have any disadvantages? Wuxi ZTE Yide Xiaobian tells you, yes. Compared with 316L stainless steel, the disadvantages of 2205 duplex stainless steel are as follows:

1. The universality and versatility of 2205 duplex stainless steel are not as good as that of 316L stainless steel. For example, for long-term applications, the temperature of the medium used must be controlled below 250 degrees, and only 316L stainless steel can be competent.

2. The plasticity and toughness of 2205 duplex stainless steel are lower than that of 316L stainless steel, and the cold and hot processing technology and forming performance are also poor.

3. It has medium temperature brittleness, and it is necessary to strictly control the processing system of heat treatment and welding to avoid harmful phases and damage performance.

4. The main reason for the weakness of duplex stainless steel compared with austenitic stainless steel is that 2205 duplex stainless steel contains a large amount of ferrite.

Will medical alcohol and edible alcohol cause harm to 304 stainless steel water cups?

Stainless steel water cups cannot hold acidic beverages. Acidity and alkalinity will cause corrosion of the inner wall of the 304 stainless steel water cup. Will medical alcohol and alcohol consumption cause corrosion damage to the stainless steel water cup?

First of all, let’s understand the composition of alcohol and 304 stainless steel. The main component of alcohol, alcohol, is an organic substance composed of three elements: carbon, hydrogen, and oxygen. It has the characteristics of evaporation and melting. At the same time, alcohol with higher concentrations will also produce chemical changes to metal materials, plastics, and plastics. 304 stainless steel is a practical 304 stainless steel. The main components are C≤0.08%, Si≤1.00%, Mn≤2.00%, 8%≤Ni≤15%, and 18%≤Cr≤20%. It has good characteristics and mainly reflects in formability and corrosion resistance.

If you simply master the composition of alcohol and 304 stainless steel, you will find that alcohol with a higher concentration is corrosive, while the content of medical alcohol is only 75%, and the content of food-grade plastic alcohol will be lower, so the difference between medical alcohol and food-grade plastic alcohol Corrosion will be almost zero. At the same time, the 304 stainless steel plate has good corrosion resistance, so medical alcohol and food-grade plastic alcohol will not cause corrosion to the inner wall of the 304 stainless steel water cup.

Russia researches to improve the durability of aviation Ti-6Al-4V titanium alloys

Two-phase titanium alloys are widely used in aerospace and engine manufacturing due to their high specific strength and corrosion resistance, but improving their durability is a pressing task in the development and production of gas turbines engine components, such as compressor blades and disks, will bear a large tensile load during operation.

At present, two-phase submicrocrystalline titanium alloys have been widely used in the world to manufacture gas turbine engine components operating under high cyclic loads and high-temperature environments of 201-351 °C. But so far, the fatigue strength of titanium alloys in this working temperature range has not been studied. Scientists from the Faculty of Mechanics and Technology of the Perm University of Technology studied the properties of the Ti-6Al-4V alloy composed of aluminum, vanadium, and titanium and evaluated the alloy’s performance at a maximum temperature of 351°C.

According to the researchers, the test was carried out using hot-rolled Ti-6Al-4V alloy bars with a diameter of 20 mm, which underwent standard heat treatment: hardening at 966 °C and annealing at 676 °C for 4 hours; At the temperature of 651°C, the rods were processed by four equal-diameter angular extrusions; finally, the mechanical tensile tests were carried out at room temperature and 351°C.

All samples used for fatigue testing were made by turning and mechanical polishing and the microstructure of the material was analyzed in longitudinal sections of the rod using transmission electron microscopy.

Compared with the coarse-grained alloy, the Ti-6Al-4V ultrafine-grained alloy obtained by equal angular extrusion exhibited higher tensile strength and higher strength at the working temperature of 351 °C. The research was carried out within the framework of the Academic Strategic Leadership Programme “Initiatives-2030” in accordance with the national mandate. In 2021, Perm University of Technology received a grant of 100 million rubles from the “Initiative-2030” program. “Initial-2030” is the largest program in Russian history to support and develop higher education institutions.