W.Nr.1.4539, X2NiCrMoCu25205, CN2MCuN super austenitic stainless steel X1NiCrMoCu25-20-5

Overview of 1.4539 Super Austenitic Stainless Steel:

1.4539 (904L, N08904, 0Cr20Ni25Mo4.5Cu) super austenitic stainless steel contains 14.0-18.0% chromium, 24.0-26.0% nickel, 4.5% molybdenum. 904L super austenitic stainless steel is a low-carbon high-nickel, molybdenum austenitic stainless acid-resistant steel. It is a proprietary material introduced by the French company H · S. Has good activation-passivation transformation ability, excellent corrosion resistance, good corrosion resistance in non-oxidizing acids such as sulfuric acid, acetic acid, formic acid, and phosphoric acid, and good in neutral chloride-containing media Resistance to pitting corrosion, and has good resistance to crevice corrosion and stress corrosion. It is suitable for sulfuric acid of various concentrations below 70 ° C. It also has good corrosion resistance in acetic acid at any concentration and temperature under normal pressure, and mixed acids of formic acid and acetic acid.

Super austenitic stainless steel 1.4539 (904L, N08904, 0Cr20Ni25Mo4.5Cu) is a high-carbon austenitic stainless steel with low carbon content. It has good corrosion resistance in dilute sulfuric acid, and is specially designed for harsh environments. design. It has a high chromium content and sufficient nickel content. The addition of copper makes it highly resistant to acids, especially highly resistant to chloride interstitial corrosion and stress corrosion cracking, and is not prone to corrosion spots and cracks. The corrosion ability is slightly better than other steels, and it has good processability and weldability, and can be used in pressure vessels.

 

Chemical composition of 1.4539 super austenitic stainless steel:

C≤	Si≤	Mn≤	P≤	S≤	Cr≥	Ni≥	Mo≥	N≤	Cu≤
0.02	1.00	2.00	0.045	0.035	19.0 23.0	23.0 28.0	4.00 5.00	0.10	1.0 2.0

 

Physical and mechanical properties of 1.4539 super austenitic stainless steel:

Density: 8.24g / cm3.

Tensile strength: σb≥520Mpa.

Yield strength: σ0.2≥216Mpa

Elongation: δ≥35%.

 

1.4539 Super Austenitic Stainless Steel Metallographic Structure:

1.4539 super austenitic stainless steel is a completely austenitic structure. Compared with austenitic stainless steels with high molybdenum content, 1.4539 is not sensitive to the precipitation of ferrite and α phase.

 

Corrosion resistance of 1.4539 super austenitic stainless steel:

Since the carbon content of 1.4539 is very low (0.020% max), no carbides will be precipitated in the case of general heat treatment and welding. This eliminates the risk of intergranular corrosion that typically occurs after heat treatment and welding. Due to the high chromium-nickel-molybdenum content and the addition of copper, 1.4539 can be passivated even in reducing environments such as sulfuric acid and formic acid. The high nickel content results in a lower corrosion rate in the active state.

In pure sulfuric acid in the concentration range of 0 ~ 98%, the use temperature of 1.4539 can be as high as 40 degrees Celsius. In pure phosphoric acid with a concentration range of 0 to 85%, its corrosion resistance is very good. In the industrial phosphoric acid produced by the wet process, impurities have a strong influence on the corrosion resistance. Among all kinds of phosphoric acid, 1.4539 has better corrosion resistance than ordinary stainless steel. Among the highly oxidizing nitric acid, 1.4539 has lower corrosion resistance compared to the high alloyed steel grades that do not contain molybdenum. In hydrochloric acid, the use of 1.4539 is therefore limited to lower concentrations of 1-2%. In this concentration range. Therefore, the corrosion resistance of 1.4539 is better than that of conventional stainless steel. Therefore, 1.4539 steel has a high resistance to pitting corrosion.

Its resistance to crevice corrosion is also good in chloride solutions. Therefore, the high nickel content of 1.4539 reduces the corrosion rate in pits and crevices. Ordinary austenitic stainless steels may be sensitive to stress corrosion in a chloride-rich environment at temperatures above 60 degrees Celsius. This sensitization can be reduced by increasing the nickel content of the stainless steel. Due to the high nickel content, 1.4539 has a high resistance to stress corrosion cracking in chloride solution, concentrated hydroxide solution and hydrogen sulfide-rich environments.

 

Processing performance of 1.4539 super austenitic stainless steel:

1. Welding performance: 1.4539 (904L, N08904, 0Cr20Ni25Mo4.5Cu) super austenitic stainless steel can be welded by various welding methods. The most commonly used welding methods are manual arc welding or inert gas shielded welding. The electrode or wire metal is based on the composition of the base metal and has a higher purity. The content of molybdenum is higher than the base metal. Pre-heating is generally not required before welding, but in cold outdoor operations, in order to avoid condensation of water vapor, joint parts or adjacent areas can be uniformly heated. Note that the local temperature should not exceed 100 ° C to avoid carbon accumulation and intergranular corrosion. Welding should use small linear energy, continuous and fast welding rate. Generally no heat treatment is required after welding. If heat treatment is required, it must be heated to 110 ~ 1150 ° C and then quickly cooled.

2. Machining performance: 1.4539 (904L, N08904, 0Cr20Ni25Mo4.5Cu) super austenitic stainless steel machining characteristics are similar to other austenitic stainless steels, and there is a tendency of sticking knife and work hardening during processing. It is necessary to use a positive rake angle carbide tool with sulfurized and chlorinated oil as the cutting coolant. The equipment and technology should be based on reducing work hardening. Avoid slow cutting speed and feed during cutting.

 

1.4539 Super Austenitic Stainless Steel Welding Materials:

Welding rod: E385-16 / 17, welding wire: ER385.

 

1.4539 super austenitic stainless steel applications:

1. Petroleum and petrochemical equipment, such as reactors in petrochemical equipment.

2. Storage and transportation equipment of sulfuric acid, such as heat exchangers.

3. The power plant flue gas desulfurization device, the main use parts are: the tower body of the absorption tower, the flue, the door panel, the internal parts, the spray system, etc.

4. Scrubber and fan in organic acid treatment system.

5. Seawater treatment equipment, seawater heat exchangers, paper industry equipment, sulfuric acid, nitric acid equipment, acid production, pharmaceutical industry and other chemical equipment, pressure vessels, food equipment.

6. Centrifuges and reactors in pharmaceutical factories.

7. Food machinery for soy sauce tank, cooking wine, salt tank, equipment and dressing.

8. Equipment and components for strong corrosive media of dilute sulfuric acid.