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

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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?

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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

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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.

Customer orders in Serbia have been successfully delivered

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As many people traveled to Xinjiang and Tibet from June to July this year, which led to a new round of epidemic outbreaks and brought us many interruptions, which seriously affected the delivery date we agreed with our customers.

Our customers were facing a lot of pressure due to the urgent need for goods from end users. The customer kept pushing us and we pushed our factory to speed up the progress every day.

After much cooperation, finally, after 2.5 months of intense production, we successfully shipped the goods on October 17, 2022, helping our customer to solve the urgent need, and our customer was very happy. The road ahead in life is always full of thorns, bends, and surprises.

Here are the photos of the goods to share with you:

If you have ASTM A179, A192, A210 A-1/C, A213 TP304/304L, TP316/316L, T5/T9/T11/T22, A334 Gr.1/3/6, 09CrCuSb, welcome to contact us. Email: [email protected]

What is the corrosion resistance of pure nickel NICKEL200?

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Nickel base alloy has excellent corrosion resistance, and has high corrosion resistance in many substances and even strong corrosive substances. Nickel base alloys have excellent physical and technological properties, but they are generally not used casually because of their high price. However, due to the development trend of high main parameters (temperature, working pressure, material concentration) in the whole process of chemical plants, there are more and more places with strong corrosivity, and the corrosion standards are becoming more and more strict. Therefore, the common machinery and equipment are not only required to be resistant to overall corrosion but also more and more resistant to pitting, stress corrosion, gap corrosion, etc. When selecting raw materials, we should not only consider the one-time project investment cost but also consider the maintenance, depreciation, shutdown loss, and other costs and their safety factors. Therefore, we pay more attention to the stability of the long-term operation of machinery and equipment. This element promotes the use of nickel-based alloys with high corrosion resistance.

At present, most of the nickel base alloys commonly used in the processing and manufacturing industry adopt the models of international standards. Therefore, the following is dominated by the American nickel base wrought aluminum alloy, and a brief and detailed introduction to pure nickel is given.

Pure nickel has good corrosion resistance in hot concentrated alkaline solution, does not cause alkali ductile stress corrosion cracking, and has good corrosion resistance to water, seawater, high- temperature dry fluoride, but is not corroded by oxidizing acid, aqueous solution with reducing agent and most of its molten metal materials. It can corrode and become brittle in gas with high-temperature sulfur content. With the increase of nickel content in stainless steel and nickel base alloy, the corrosion resistance in dilute hydrochloric acid, sulfuric acid, and ammonium sulfate is significantly enhanced, and the stress corrosion resistance in sodium hydroxide solution is also significantly enhanced. The corrosion resistance in caustic soda solution is basically positive correlation with nickel content.

For a pure nickel, the market generally includes NICKEL200 and NICKEL201

NICKEL200 COMPOSITION:

Carbon C ≤ 0.15

Silicon Si ≤ 0.35

Manganese Mn ≤ 0.35

Sulfur S ≤ 0.01

Nickel Ni+Cobalt Co greater than or equal to 99

Copper Cu ≤ 0.25

Fe ≤ 0.4

NICKEL200 is mainly used to solve the problem of oxidizing halogen system vapor, alkali solution, non-reducing acid salt, organic acid, and other machinery, equipment, and components. In the application, the temperature should be less than 315 ℃ in the natural environment. NICKEL200 corrosion resistance: corrosion is relatively slow in the air, and HCl has excellent corrosion resistance in various sulfuric acids in the sea. However, it should be used cautiously in HIC acid with high water flow. It is not easy to use in H3PO4 and HNO3. It has very good corrosion resistance in H2SO4, which is only used to block gas, in HF without water at high temperature, in chlorine and HCl at high temperature, and in chlorine and fluorine.

Welding method of 316L stainless steel round steel

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The most commonly used welding method for 316L stainless steel round steel is manual welding. The most commonly used welding method for stainless steel is manual welding (MMA), followed by metal gas-shielded welding (MIG/MAG) and tungsten inert gas-shielded welding. (TIG).

Preparation before welding: The thickness of 4mm or less does not need to be broken, and it is directly welded, and one side is welded through once. Butt welds with a thickness of 4 to 6mm can be welded on both sides of the joint without opening. More than 6mm, generally open V or U, X-shaped groove.
Next: Degrease and descale the weldment and filler wire. to ensure welding quality.

Welding parameters: including 316L stainless steel round steel welding current, tungsten electrode diameter, arc length, arc voltage, welding speed, shielding airflow, nozzle diameter, etc.
(1) Welding current is a key factor in determining weld formation. It is usually determined according to the weldment material, thickness, and groove shape.
(2) The diameter of the electrode is determined according to the size of the welding current. The larger the current, the larger the diameter.
(3) Welding arc and arc film, the arc length range is about 0.5 to 3mm, and the corresponding arc voltage is 8~10V.
(4) Welding speed: The selection should take into account factors such as current size, weldment material sensitivity, welding position, and operation mode.

The above is the welding method of 316L stainless steel round steel that Xiaobian shared with you today, I hope it can be useful to everyone!

Is the faucet material all copper or copper alloy?

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There are many materials for faucets, such as stainless steel and copper. Is the faucet material all copper or copper alloy better? Let me take you all to find out.

The faucet is better to choose all copper material. The all-copper material can kill 99% of the bacteria in tap water. Even if the tap water bursts and causes foreign objects to enter, there is no need to worry about a bacterial infection; good metal-cutting performance reduces production costs, making it a must-have copper faucet for every household.

The main material of kitchen faucets currently used in China is brass HPb59, which contains trace amounts of lead. At present, the national faucet safety certification rules stipulate that the inspection should be carried out in accordance with the regulations, and the amount of lead precipitation should be less than or equal to 11 micrograms. At present, the lead-washing technology of big brands can inhibit the precipitation of most heavy metals.

The price of copper alloy faucets is much lower than that of full copper faucets, and this faucet is easier to produce on a large scale. The biggest disadvantage of alloy faucets is that they have no toughness and are prone to cracks after long-term use, and their service life is short.

Which is better, titanium alloy or stainless steel?

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Differences between titanium and titanium alloy and stainless steel

The density of titanium and titanium alloy is only 4.51, which is smaller than that of steel and only half the weight of steel, but its strength is similar to that of ordinary carbon steel. Titanium belongs to the thermodynamically unstable metal, which is very active. Titanium can form a natural oxide film (titanium dioxide) with air. This stable, strong adhesion, and good protective character oxide film determines the corrosion resistance of titanium, so titanium has excellent corrosion resistance. Next, it has a light texture, high tensile strength, and good mechanical properties.

Titanium alloys can be divided into corrosion-resistant titanium alloys, structural titanium alloys, heat-resistant titanium alloys, and low-temperature titanium alloys according to their applications.

1. It can be distinguished from color. Titanium is a little dark. It shows a cold color. I think it’s cool. Titanium is a little darker than steel. Steel is white, the pale kind. The two colors are very obvious.

2. It can also be distinguished by chemical methods, that is, soaking with nitric acid. Titanium does not react. The stainless steel will react strongly once it is put down. It is difficult to tell the difference between pure titanium and titanium alloy from the appearance.

3. Titanium can mark gray and black on ceramic tiles, but stainless steel cannot.

4. Good corrosion resistance of titanium: titanium alloy is easy to form a dense oxide film below 550 ℃, so it is not easy to be further oxidized. It has high corrosion resistance to air, seawater, steam, and some acids, alkalis, and soft media.

5. Good thermal strength of titanium: The melting point of titanium alloy is 1660 ℃, which is higher than that of iron. It has high thermal strength and can work below 550 ℃. At the same time, it shows good toughness at low temperatures.

6. Titanium processing is difficult: welding, electroplating, and cold stretching are very difficult. Welding and electroplating must be carried out in a vacuum or full of inert gas (vacuum ion electroplating)

Titanium alloys are widely used in various fields because of their high strength, good corrosion resistance, and high heat resistance.

The density of titanium alloy is generally about 4.51g/cm3, which is only 60% of that of steel. The density of pure titanium is close to that of ordinary steel. Some high-strength titanium alloys exceed the strength of many alloy structural steels. Therefore, the specific strength (strength/density) of titanium alloy is much higher than that of other metal structural materials, as shown in Table 7-1. Parts with high unit strength, good rigidity, and lightweight can be made. The engine components, framework, skin, fasteners, and landing gear of the aircraft are made of titanium alloy.

304 is universal stainless steel, which is widely used to make equipment and parts that require good comprehensive performance (corrosion resistance and formability). In order to maintain the inherent corrosion resistance of stainless steel, the steel must contain more than 18% chromium and more than 8% nickel.

The density is 7.93 g/cm3, also called 18/8 stainless steel in the industry. It has high-temperature resistance of 800 ℃, good processing performance, and high toughness, and is widely used in industry, furniture decoration industry, and food and medical industry.

Of course, titanium alloy is better than 304 stainless steel in terms of high strength, low density, and corrosion resistance

Several culprits of stainless steel rust

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Many people believe that stainless steel will not rust. In fact, everything has a life span. Stainless steel is also a kind of metal, which will be oxidized and corroded in nature, causing rust; The only difference is that the material or protection degree is different, which can delay the probability and time of rusting to the greatest extent. However, in many cases, stainless steel will also be “rusted”. Here are the main culprits of stainless steel rust:

1、 Presence of chloride ions in the service environment

Chloride ions mainly exist in purified liquids and gases. The use of stainless steel in the presence of chloride ions will accelerate its corrosion, even exceeding that of ordinary low-carbon steel. Therefore, there are requirements for the use environment of stainless steel, and it needs to be wiped frequently to remove dust and keep it clean and dry.

2、 Without solution treatment

Solution treatment: refers to the heat treatment process that heats the alloy to the high-temperature single-phase area and maintains the constant temperature, so that the surplus phase can be fully dissolved in the solid solution and then rapidly cooled to obtain the supersaturated solid solution. Its purpose is to fully dissolve various phases in the alloy, strengthen solid solution, improve toughness and corrosion resistance, eliminate stress, and soften, so as to continue processing or molding. If the alloy elements are not dissolved in the matrix material, the alloy content in the matrix structure is low and the corrosion resistance is poor.

3、 Natural intergranular corrosion

Under the action of a corrosive medium, a corrosion phenomenon between grains of stainless steel is called intergranular corrosion. When the stainless steel with intergranular corrosion is subjected to stress, it will fracture along the grain boundary and the strength will almost disappear. This is the most dangerous form of stainless steel damage.

Stainless steel will not rust because the content of chromium (Cr) and nickel (Ni) has reached a certain standard. These two alloys are the key to rust prevention in stainless steel. Generally, stainless steel produced by small factories will rust, mainly because of the low nickel content (the cost price of nickel largely reflects the benchmark price of stainless steel); If the nickel content reaches the standard required by various stainless steel, no matter how you cut it, it will not rust.

4、 Mechanical stress corrosion

When stainless steel materials are made into products, they need to go through such processes as stamping, shearing, punching, stretching, grinding, shearing, bending, planing, thermal cutting, or welding. Because of the external stress loading, the machined parts and their edges will be damaged by their own stress to a large extent, which will lead to the intergranular transformation; Therefore, it destroys its corrosion resistance and speeds up the rusting process.

5、 Damage to surface passivation protective layer

Passivation is a method to change the metal surface into a state that is not easy to be oxidized, thus delaying the corrosion rate of the metal. Passivation is due to the interaction between metal and oxidizing substances. During the interaction, a very thin, dense, well-covered, and firmly adsorbed passivation film is formed on the metal surface. Once this “protective film” is damaged by external forces (mainly large scratches), the stainless steel is like a body without resistance, which is easy to react with the outside world to rust and corrosion.

The application practice of stainless steel pipes tells you where the advantages are!

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Stainless steel material is a recognized healthy material that can be implanted into the human body and is used in almost all fields involving human health. It has been widely used. The Stainless steel water pipe is an environmentally friendly material that meets health requirements, can be 100% recycled, saves water resources, reduces transportation costs, reduces heat loss, and avoids sanitary ware pollution. The details are as follows:

1. Lifespan

Stainless steel tubing has the longest service life. From the analysis of the use of stainless steel abroad, the service life of stainless steel water pipes can reach 100 years, or at least 70 years, which is as long as the life of buildings.

2. Corrosion resistance

One of the most prominent advantages of stainless steel pipe is its excellent corrosion resistance, which is the best among all kinds of pipes. Because stainless steel can passivate with oxidant, a tough and dense chromium-rich oxide protective film Dr2O3 is formed on the surface, which can effectively prevent the further oxidation reaction.

And other metal pipes, such as galvanized water pipes and copper pipes, have little passivation ability, which is the key reason why the corrosion resistance of copper pipes of galvanized pipes is far less than that of stainless steel pipes. Stainless steel does not corrode uniformly like carbon steel, and no protective coating is required for use; with stainless steel water pipes, there is no limit to the chemical composition of water, because stainless steel has good performance in water of various oxygen content, temperature, PH and hardness Corrosion resistance; stainless steel water pipes can withstand high flow rates, even if the flow rate is greater than 40 m/s, it still maintains a very low corrosion rate, no more than 0.003 mm/year, especially suitable for high-rise water supply.

Stainless steel generally does not suffer from localized corrosion. The chloride content that 304 stainless steel can withstand is up to 200ppm, and the chloride content that 202 stainless steel can withstand is up to 1000ppm. This conclusion is based on exposure experimental data and has been confirmed by experience. The thermal expansion coefficient of stainless steel pipe is similar to that of copper pipe, which is 1.5 times that of ordinary steel pipe. Compared with stainless steel pipe, it has the characteristics of slow thermal expansion and cold contraction.

3. Heat resistance and heat preservation

The thermal conductivity of stainless steel pipe is 1/25 of copper pipe and 1/4 of ordinary steel pipe, especially suitable for hot water transportation. The most commonly used stainless steels in the water industry are 202 and 304 stainless steels, which can meet the vast majority of water treatment and delivery conditions.

4. Strength

The tensile strength of 304 stainless steel pipe is 2 times that of steel pipe and 8-10 times that of plastic pipe. The strength of the material determines whether the water pipe is strong, crash-resistant, safe, and reliable. Safety and reliability are the most important requirements for building water supply. Under the circumstance of being hit by an external force, the possibility of leakage of the stainless steel water pipe is extremely small. The working pressure of a high-rise water supply system is generally greater than 0.6Mpa, which requires higher pressure on pipes.