How to distinguish austenitic ferrite by the grade of steel

1: Grade S32205 duplex stainless steel.

Two: Chemical composition:

c≤ mn≤ si≤ p≤ s≤ cr ni<>

Three: the scope of application, the field of application:

Pressure vessels, high-pressure storage tanks, high-pressure pipes, heat exchangers (chemical processing industry). Oil and gas pipelines, heat exchanger fittings. Sewage treatment system.

Pulp and paper industry sorters, bleaching equipment, storage and handling systems. Rotary shafts, press rolls, blades, impellers, etc. in high-strength and corrosion-resistant environments. Cargo boxes for ships or trucks.

Food processing equipment.

Fourth, physical properties.

2205 Density: , Melting Point: 1300-1390, Magnetic: None Heat Treatment: 1000-1050 Between 1-2 hours of heat preservation, rapid air cooling or water cooling.

Five: Overview. The yield strength of 2205 duplex stainless steel is austenitic stainless steel.

This property allows designers to reduce weight when designing products, giving this alloy an advantage over 316,317L. This alloy is particularly suitable for temperatures ranging from -50°F to +600°F. This alloy can also be considered for applications beyond this temperature range, but there are some limitations, especially when applied to welded structures.

Series 3 stainless steels are all austenitic stainless steels. The ferritic stainless steel you are talking about is 4 series, and 430 is the most representative steel grade, commonly known as stainless iron.

I am mainly engaged in stainless steel, taking stainless steel as an example, the grade 304 316 321 is austenitic stainless steel.

S32205, S31803 and S32750 are austenitic-ferritic duplex stainless steels, and 13CR are martensitic stainless steels.

Ferritic stainless steel has not been touched. I don't see anything that shows the meaning of the organization.

Distinguish. First, the essence is different.

Ferrite. It is an interstitial solid solution in which carbon is dissolved in -Fe.

Austenite. It is a lamellar microstructure of steel, and is a non-magnetic solid solution with a small amount of carbon in -Fe.

Distinguish. Second, the structure is different.

Ferrite has a body-centered cubic lattice structure, the grain boundaries are smooth, twins or slip lines are rarely seen in the grain, the color is light green, shiny, and dark after deep corrosion. Ferrite in steel is present in sheets, blocks, needles, and reticules.

The austenite is a face-centered cubic structure, and the interstitial atoms such as carbon and nitrogen are located in the center of the octahedral gap of the austenite unit cell, and the center of the face-centered cubic unit cell and the midpoint of the edge.

Characteristics of austenite

There are many lattice slip systems of austenite, so the plasticity of austenite is good and the yield strength is good.

Low, easy to process plastic forming. Therefore, ingots, billets, and steel are generally heated to more than 1100 C for austenitization, and then forged, plastically processed into lumber or processed into parts.

The austenite in steel in general is paramagnetic.

Therefore, austenitic steel can be used as a non-magnetic steel. However, the special composition of Fe-Ni soft magnetic alloy also has austenite structure, but it is ferromagnetic.

Austenite has poor thermal conductivity, large linear expansion coefficient, and a higher expansion coefficient than ferrite and cementite.

About twice as tall. Therefore, austenitic steels can be used to make instrumentation elements that are sensitive to thermal expansion.

Austenitic steel is steel with austenitic structure at room temperature, and ferritic steel is steel with ferrite at room temperature.

According to the iron-carbon phase diagram, austenite generally exists above the A1 temperature, but if alloying elements (such as CR) are added, the austenite region will be expanded, so the austenite state can also be maintained at room temperature;

Ferritic steel is relatively easy to produce because of its low carbon content.

It's ctrl+c&ctrl+v, but it's quite clear.

Austenitic stainless steel: The steel that contains cr and the stable austenite elements ni, mn, n, etc., which make the steel single-phase austenite at room temperature is called austenitic stainless steel. This type of steel contains more elements that expand the zone and stabilize austenite, which is homogeneous at high temperature, and has austenite structure at room temperature because the MS point is below room temperature when cooling.

Ferritic steel: stainless steel with a ferritic structure as the main structure in the service state. The chromium content is 11% to 30%, and it has a body-centered cubic crystal structure.

Ferrite crystal structure? This type of steel is high chromium steel, and it can be seen from the Fe-CR phase diagram that due to the stabilization of chromium, when the chromium content reaches 13%, the iron-chromium alloy will have no phase transformation and will remain ferrite from high to low temperature. And because the chromium content reaches 12% and can resist corrosion, this kind of ferritic steel becomes ferritic stainless steel.

Rigid materials are classified according to metallographic structure, and can be divided into pearlitic steel, bainite steel, martensitic steel and austenitic steel in the normalized state.

Austenitic steel has a non-magnetic structure and good cold working properties. The corrosion resistance is better than that of 430 and other martensitic steels, and the heat resistance is better. Cons:

**Expensive, difficult thermal deformation, slightly worse intergranular corrosion and stress corrosion performance. Most austenitic steels are composed of Cr-Ni, such as Cr18Ni9Ti.

Ferritic steel.

Low-carbon chromium stainless steel containing more than 14, chromium stainless steel containing chromium 27, and stainless steel with molybdenum, titanium, niobium, silicon, aluminum, tungsten, vanadium and other elements added on the basis of the above components, the elements that form ferrite in the chemical composition are absolutely dominant, and the matrix structure is iron. The structure of this type of steel is ferrite in the quenched (solid solution) state, and a small amount of carbide and intermetallic compounds can be seen in the annealed and time-sensitive state.

Belonging to this category are CRL7, CR17MO2TI, CR25, CR25MO3TI, CR28, etc. Because of its high chromium content, ferritic stainless steel has good corrosion resistance and oxidation resistance, but poor mechanical and technological properties, and is mostly used in acid-resistant structures with little stress and as oxidation-resistant steel.

The cold rolling processing of ferritic stainless steel strip increases the roughness of the work roll, and the work roll is divided into a finishing roll, which is used for the last pass rolling, and the rough roll is used for the rest of the pass rolling; The pressure rate of the first three passes decreases and increases, the rest of the passes decrease in the press rate, and the last pass is controlled in the front and back tension of the control pass, and the unit tension is not more than kilogram mm The roughness of the work roll is improved, so that the ability to eliminate surface defects is improved, the cost is reduced, and the rolling speed and output are improved. Adjust the depression rate, so that the anisotropy of the material can be effectively controlled, and the product quality is improved.

The front and rear tension is controlled to reduce the slippage and break the belt and twist the accident, and the plate shape is improved.

1. Differences in attributes.

Martensite is a tissue name for ferrous metals.

Ferrite is a type of interstitial solid solution.

Austenite is a laminar microstructure of steel.

2. Differences in meaning.

Martensite is a supersaturated solid solution of carbon in -Fe.

Pure iron below 912 has a body-centered cubic lattice. The interstitial solid solution of carbon dissolved in -fe is called ferrite and is denoted by the symbol f.

Austenite is usually a non-magnetic solid solution with a small amount of carbon in -Fe, also known as Vostin iron or -Fe.

3. Differences in characteristics.

Martensite is a body-centered square structure, and austenite is a face-centered cubic structure.

Martensite is less dense than austenite, so it expands in volume after transformation. Compared with the volume change caused by the transformation, the shear stress and tensile stress caused by this change need more attention.

Ferrite: has a body-centered cubic lattice. It has good plasticity and toughness, but low strength and hardness, and slow cold work hardening.

4. The difference in form.

The three-dimensional structure of martensite is usually plate-like or lath-like.

Austenite is generally composed of equiaxed, polygonal grains with twin crystals within the grains. The austenite grains just after the heating transition are relatively small, and the grain boundaries are irregularly arced.

The ferrite grain boundaries are smooth, twins or slip lines are rare in the crystal, and the color is light green and shiny, and it is dark after deep corrosion. Ferrite in steel is present in sheets, blocks, needles, and reticules.

I can't finish this for a few days and nights.

Austenite is a face-centered structure with many tissue bonds and is non-magnetic.

The ferrite body core structure has few metallic bonds and can be magnetized attracted.

Martensite is a kind of ferrite transition structure, suitable for quenching for knife steel, these three states of steel have substitute steel, so it is difficult to say which one is good and which is bad, depending on which aspect you use.

In general, Austenthian (ferrite, martensis).

In terms of application, austenite is more extensive.

There is also a type of steel called duplex steel, a combination of ferrite and austenite.

The addition of manganese and nickel reduces the critical transition temperature of austenite below room temperature, allowing the steel to maintain its austenitic structure at room temperature, the so-called austenitic steel.

The shape, size, and structure of tissues are not the same.

Martensitic stainless steel contains CR12-18%; Ferritic stainless steel contains 15-30% CR, and ferritic stainless steel has a low carbon C content

Low carbon martensitic stainless steel 1cr cr cr 13 high carbon martensitic 9cr18 carbon cr 18%.

Commonly used CR content of ferrite % austenitic stainless steel contains Ni, Cr, Mn, N

For example, 304 austenitic stainless steel, national standard grade: 0Cr18Ni9, Cr18%, Ni9%.

For details, you can check the stainless steel manual.

The main elements are Cr, Ni and C content.

The chemical composition mainly depends on the content of CR and Ni elements.