Question 1: What is austenitic stainless steel? Erlenmeyer stainless steel: stainless steel with austenitic structure at room temperature. When the chromium content is about 18%, the nickel content is about 8% ~ 10%, and the carbon content is about 0. 1%, the steel has a stable austenite structure. Austenitic Cr-Ni stainless steel includes the famous 18Cr-8Ni steel and the high Cr-Ni series steel developed by adding Mo, Cu, Si, Nb and Ti. Austenitic stainless steel is nonmagnetic and has high toughness and plasticity, but its strength is low, so it can not be strengthened by phase transformation, but only by cold working. If sulfur, calcium, selenium, tellurium and other elements are added, it has good cutting performance. In addition to the corrosion resistance of oxidizing acid medium, this steel can also resist the corrosion of sulfuric acid, phosphoric acid, formic acid, acetic acid and urea if it contains elements such as Mo and Cu. If the carbon content in this steel is less than 0.03% or contains Ti and Ni, its intergranular corrosion resistance can be significantly improved. High silicon austenitic stainless steel has good corrosion resistance in concentrated nitric acid. Austenitic stainless steel is widely used in all walks of life because of its comprehensive and good comprehensive properties. Austenitic steel (1)1Cr17mn6ni15n; (2) 1cr 18 Mn 8 ni 5n； (3) 1cr 18ni 9； (4) 1cr 18 ni 9 si 3； (5)0cr 18ni 9； (6)00cr 19ni 10； (7)0cr 19 ni9 n； (8)0cr 19ni 10 nbn； (9)00cr 18ni 10N； ( 10) 1cr 18ni 12； ( 1 1)0 Cr 23 ni 13； ( 12)0 Cr 25 ni 20； ( 13)0cr 17ni 12mo 2； ( 14)00cr 17ni 14mo 2； ( 15)0cr 17ni 12mo 2n； ( 16)00cr 17ni 13mo 2n； ( 17) 1cr 18ni 12mo 2 ti； ( 18)0cr 18ni 12mo 2 ti； ( 19) 1cr 18ni 12mo 3 ti； (20)0cr 18ni 12mo 3 ti； (2 1)0cr 18ni 12mo 2cu 2； (22)00cr 18ni 14 mo 2 Cu 2； (23)0cr 19ni 13mo 3； (24)00cr 19ni 13mo 3； (25)0cr 18ni 16mo 5； (26) 1cr 18 ni9 ti； (27)0cr 18ni 10Ti； (28)0cr 18ni 1 1Nb； (29) 0cr18ni13si4304316 are foreign brands.

Question 2: What material belongs to austenitic steel? The American Iron and Steel Association uses three numbers to represent various standard grades of malleable stainless steel. These include:

① Austenitic stainless steel is marked with the serial numbers of 200 series (Cr-Mn-N stainless steel without nickel or low nickel) and 300 series (Ni-Cr stainless steel).

② Ferritic and martensitic stainless steels are represented by 400 series numbers.

Among all kinds of steel, there are many kinds and brands of stainless steel, about hundreds of brands, and 200 are standardized and non-standardized. The most commonly used are the following varieties:

= = Comparison table of common stainless steel materials = = =

Japanese, American, British, German, French and China.

sus 304 304 304s 15 x 5 crni 189 z6cn 18.09 0cr 18ni 9

sus 304 l 304 l 304s 12 x2 crni 189 z2cn 18.09 00 Cr 18 ni 10

sus 3 16 3 16 3 16s 16 x 5 Cr nimo 18 10 z 6 CND 17. 12 0cr 18ni 12mo 2 ti

sus 3 16L 3 16L 3 16s 12 x2 crni mo 18 10 z2cn d 17. 12 00cr 17ni 14 mo 2

sus 3 17 3 17 3 17s 16-0cr 18ni 12mo 3 ti

sus 3 17L 3 17L 3 17s 12 x2 crni mo 18 16 z2cn d 19. 15 00cr 17ni 14mo 3

sus 32 1 32 1 32 1s 12 x 10 crni 189 z6 CNT 18. 10 0cr 18 ni 9 ti

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200 series stainless steel is Cr-Mn-N series stainless steel. Different from 300 series stainless steel, this series of stainless steel may or may not contain nickel, but the nickel content of stainless steel commonly used in industry at present is about 3%-5%. The birth of 200 series stainless steel is mainly to solve the shortage of nickel resources. The two core elements of 200 series stainless steel are manganese and nitrogen.

300 series stainless steel is austenitic stainless steel, nitrogen is a strong austenite forming element, and it is also a interstitial element because of its small atomic radius. However, the solubility of nitrogen in steel is low, so if nitrogen is to be used to form austenite, a sufficient amount must be added. Functionally speaking, 1 nitrogen is equivalent to 30 nickel, which means that the austenite forming ability of nitrogen is 30 times that of nickel, but the solubility of nitrogen is limited, which leads to a problem, that is, how to add nitrogen to stainless steel. Manganese can increase the solubility of nitrogen in steel, so manganese must be added in smelting, and the combination of manganese and nitrogen can promote the formation of austenite. However, when the chromium content is greater than 15%, adding manganese alone will not produce austenite-forming elements even if it reaches 25%, and the combination of manganese and chromium will reduce the corrosion resistance of stainless steel and have a negative impact on the use of stainless steel. In a word, adding manganese to stainless steel is limited by two aspects: first, manganese exceeding 10% will affect the corrosion resistance of stainless steel; Secondly, manganese vapor will volatilize. As a welding structure, manganese vapor is harmful to workers, so the content of manganese is below 10%.

The content of chromium in 200 series stainless steel is generally around 17%; Not less than 16%. This is because: first; Forming austenite; To achieve non-magnetism, so much chromium must be added; Secondly, the original intention of developing 200 series stainless steel is to replace 304 stainless steel, so its chromium content should be close to 304 to ensure its corrosion resistance; Third, considering the cost, this content is also more reliable.

Present situation of 200 series stainless steel;

American 200-series stainless steel has more than 10 standards, with an annual output of 50,000 tons, accounting for 2.5% of the crude stainless steel output. In 2000, the output of 200 series stainless steel in India was 400,000 tons.

According to the analysis of the basic research, formation process and present situation of 200 series stainless steel, 200 series stainless steel is divided into two parts in the current market:

First, the chromium content is 17% ~ 18%, and the contents of manganese, nitrogen and nickel are controlled according to the actual situation of forming austenite balance;

2. The components of J4 brand in India (non-international brand) are as follows: 0. 1% carbon, 8.5%- 10% manganese; 15%- 16% chromium, 1.2% nickel, 1...> & gt

Question 3: What are austenitic steel and ferritic steel? Although it is Ctrl+C&; Ctrl+v, but it's clear

Austenitic stainless steel: a steel containing chromium and relatively stable austenitic elements such as nickel, manganese and nitrogen. , making steel single-phase austenite at room temperature, called austenitic stainless steel. This kind of steel contains a large number of elements that expand γ zone and stabilize austenite, all of which are γ phase at high temperature, and have austenite structure at room temperature because Ms point is lower than room temperature when cooling.

Ferrite steel: stainless steel with ferrite structure. The chromium content is 1 1%~30%, and it has a body-centered cubic crystal structure. (Ferrite crystal structure? This kind of steel is high chromium steel. According to the Fe-Cr phase diagram, due to the effect of chromium stabilizing α, when the chromium content reaches 13%, the Fe-Cr alloy will have no γ phase transformation and keep α ferrite from high temperature to low temperature. Because the chromium content reaches 12%, this ferritic steel becomes ferritic stainless steel.

Question 4: What is super austenitic stainless steel? What is a nickel-based alloy? Secondly, in terms of high temperature resistance or corrosion resistance, it has better high temperature resistance or corrosion resistance than 304, which is irreplaceable by 304. In addition, from the classification of stainless steel, the metallographic structure of special stainless steel is stable austenite metallographic structure.

Because this special stainless steel is a high alloy material, the manufacturing process is quite complicated. Generally speaking, people can only rely on traditional processes to manufacture this special stainless steel, such as casting, forging, rolling and so on.

In many fields, such as:

1, ocean: marine structures in the marine environment, seawater desalination, mariculture, seawater heat exchange, etc.

2. Environmental protection field: flue gas desulfurization device for thermal power generation, wastewater treatment, etc.

3. Energy field: atomic power generation, comprehensive utilization of coal, tidal power generation, etc.

4. Petrochemical field: oil refining, chemical equipment, etc.

5. Food field: salt making, soy sauce brewing, etc.

In the above fields, ordinary stainless steel 304 is incompetent. In these special fields, special stainless steel is indispensable and irreplaceable. In recent years, with the rapid development of economy and the continuous improvement of industrial level, more and more projects need higher grade stainless steel-special stainless steel (super stainless steel, nickel-based alloy).

Some representative special stainless steels are:

1, super stainless steel, that is to say, special stainless steel containing about 6% molybdenum,

There are more than a dozen steels in the world. Also called 6 molybdenum stainless steel. For example, his main ingredients are; 25Ni-23Cr-5.5Mo-0.2N

2, Inconel alloy, such as Inconel 800, its main components are; 32Ni-2 1Cr-Ti，Al

3. Inconel, such as Inconel 600, is its main component; 73Ni- 15Cr-Ti，Al

4, Hastelloy, such as C-276, its main components; 56Ni- 16Cr- 16Mo-4W

5. Monel alloy, such as Monel 400, its main components; 65Ni-34Cu

Based on the above examples, if ordinary stainless steel (304) is selected instead of special stainless steel, ordinary stainless steel (304) is not suitable for such high temperature or high corrosive environment, and the material will be corroded or oxidized immediately at high temperature. Therefore, special stainless steel is the best choice in many environments that need high temperature resistance and corrosion resistance. Special stainless steel has surpassed the traditional category of stainless steel, with outstanding performance. No matter now or in the future, there is endless demand for special stainless steel materials.

Question 5: What are austenitic steel and ferritic steel? Austenitic steel is a steel with austenite structure at room temperature, and ferritic steel is a steel with ferrite at room temperature.

According to the Fe-C phase diagram, austenite generally exists above A 1, but if alloying elements (such as Cr) are added, the austenite region will be enlarged, so the austenite state can be maintained at room temperature.

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

Question 6: What is the difference between austenitic stainless steel 304 and austenitic stainless steel? Stainless steel is divided into austenite and martensite. Common stainless steels in austenite are SUS3 16 SUSU304 SUS303 and so on. Common stainless steels in martensite are SUS440C SUS4 10, etc. The specific features are as follows:

Question 7: Are all austenitic steels stainless steel? Conceptual categories are different, so we can't say yes or no directly. Any steel with austenite as the main metallographic structure can be called austenitic steel. However, stainless steel needs to have corrosion resistance in weak corrosive medium, and usually stainless steel contains a lot of chromium. Some austenitic steels are stainless steel, such as 1Cr 18Ni9, 0Cr 19Ni9, etc.

Question 8: What do you mean by single-phase austenitic steel? Generally speaking, stainless steel can be divided into ferritic stainless steel, austenitic stainless steel, martensitic stainless steel and ferritic-austenitic duplex stainless steel.

The first three kinds are stainless steel with single metallographic structure, and the structure of the latter one contains 50% of the two kinds of structures, with at least 30% of minor phases.

Question 9: What does austenitic stainless steel seamless steel tube mean? It refers to seamless steel pipes made of austenitic stainless steel. This is a standard product.

Stainless steel seamless pipe is a kind of long steel with hollow section and no seam around it. The thicker the wall thickness of the product, the more economical and practical it is, and the thinner the wall thickness, the higher the processing cost. The technology of this product determines its limited performance. Generally, seamless steel pipe has low precision: uneven wall thickness, low brightness inside and outside the pipe, high length cost, and difficult removal of internal and external pits and black spots; Its detection and shaping must be done offline. Therefore, it shows its advantages in high pressure, high strength and mechanical structure materials.

According to the different metallographic structure of stainless steel, it can be divided into semi-ferritic semi-martensitic stainless steel seamless tube, martensitic stainless steel seamless tube, austenitic stainless steel seamless tube and austenitic-ferritic stainless steel seamless tube.

According to GB 14975-2002 Seamless Stainless Steel Pipe, the length of steel pipe (indefinite length) is usually 1.5 ~ 10m, and the hot extruded steel pipe is equal to or greater than1m. The wall thickness of cold-drawn (rolled) steel pipe is 0.5 ~1.0 ~ 7m; ， 1.0 ~ 7m； If the wall thickness is greater than 1.0mm, it is 1.5 ~ 8m.