لوله استیل ضد زنگ فوق العاده آستنیتی

What is super austenitic stainless steel tube and its performance characteristics

With the development of industrial technology, the requirements for environmental adaptability of materials are constantly increasing, especially in the fields of chemical industry, marine engineering and high-purity water treatment. Traditional stainless steel tubes can no longer meet the long-term use requirements in some highly corrosive environments. For this reason, super austenitic stainless steel tubes, as a high-alloy material, have gradually gained attention in the market. Jiangsu Jend Tube Co., Ltd., as a professional manufacturing company with a complete production cycle and rich technical experience, is committed to producing austenitic stainless steel tubes of various specifications and materials, including super austenitic series, to meet the application needs of different customers around the world.

Definition of super austenitic stainless steel tube

Super austenitic stainless steel tube refers to a type of stainless steel tube that obtains higher corrosion resistance and stronger mechanical properties by increasing the content of alloy elements, especially the proportion of chromium (Cr), nickel (Ni), molybdenum (Mo) and nitrogen (N) on the basis of traditional austenitic stainless steel. The alloy content of this type of material is significantly higher than that of the conventional 304 and 316 series, so it has better resistance to pitting, crevice corrosion and stress corrosion cracking.

Common super austenitic stainless steel grades include 904L, 254SMO, Alloy 625 (nickel-based alloys are often used in super austenitic environments), etc. These materials are widely used in fields with high requirements for corrosion resistance.

Main alloying elements and their functions

The corrosion resistance of super austenitic stainless steel tubes mainly depends on the reasonable ratio of its alloying elements:

Chromium (Cr): The increase in chromium content enhances the stability of the passivation film on the surface of the material and enhances the oxidation and corrosion resistance of the steel.

Nickel (Ni): Nickel, as an austenite stabilizing element, improves the toughness and plasticity of steel, improves low-temperature performance, and enhances overall corrosion resistance.

Molybdenum (Mo): The addition of molybdenum significantly improves the resistance to pitting and crevice corrosion caused by chloride ions, and is an indispensable element in super austenitic steel.

Nitrogen (N): Nitrogen can further improve the pitting resistance and strength, which helps to improve the overall performance of steel.

Copper (Cu): Some super austenitic stainless steels, such as 904L, contain copper, which enhances the corrosion resistance to reducing acids (such as sulfuric acid).

Performance characteristics

Corrosion resistance

Super austenitic stainless steel tubes show strong corrosion resistance in chlorine-containing environments, strong oxidizing media and acidic environments. Compared with conventional austenitic steels, this type of tube can more effectively resist pitting and crevice corrosion, and is a common material for seawater treatment equipment, chemical plants and acidic working conditions.

Mechanical properties

Due to the enhancement of alloy elements, super austenitic stainless steel tubes maintain a good balance in strength and toughness. The addition of nitrogen elements especially improves the strength, so that the tube has a certain pressure bearing capacity while ensuring corrosion resistance, and is suitable for use in high pressure and high temperature environments.

Processing performance

Although the high alloy content may increase the difficulty of material processing, after many years of process research and development by Jiangsu Jend Tube Co., Ltd., the use of precision heat treatment and cold processing technology can achieve good size control and surface quality of the tube to meet diverse engineering needs.

Resistance to stress corrosion cracking

Super austenitic stainless steel tubes have strong resistance to chloride ion stress corrosion cracking, which is particularly important for marine and chemical media environments and can effectively extend the service life of equipment.

High temperature resistance

Some super austenitic materials also have good high temperature resistance and can maintain stable organization and performance within a certain temperature range, which is suitable for industrial boilers, heat exchangers and other equipment.

Manufacturing advantages of Jiangsu Jend Tube Co., Ltd.

Jiangsu Jend Tube Co., Ltd. has a complete production system from raw material selection, smelting, heat treatment to finished product inspection. The company has established a special process for the production of super austenitic stainless steel tubes to ensure that the product meets the design requirements in terms of composition uniformity, mechanical properties and corrosion resistance.

Specifically include:

Strict raw material procurement to ensure that the content of basic alloy elements meets the standards;

Advanced smelting technology, including electroslag remelting to improve material purity;

Precision heat treatment process to optimize material structure;

Various non-destructive testing methods, such as ultrasonic flaw detection and acid corrosion testing, to ensure product quality;

Multi-specification customization capabilities to meet customers' different needs for tube diameter, wall thickness and length.

Application areas

Super austenitic stainless steel tubes are widely used in many industries due to their corrosion resistance and high temperature resistance:

Chemical and petrochemical industries: tubelines and equipment for strong acid and strong oxidizing media;

Marine engineering: seawater desalination equipment, offshore platform tubelines, etc.;

Power industry: desulfurization equipment, heat exchange systems;

Food and pharmaceutical industries: high-purity water transportation and clean environment tubeline systems;

Papermaking industry: tubelines for high-concentration acid and alkali media.

Performance deconstruction and industrial application prospects of super austenitic stainless steel tubes

In modern industrial systems, as chemical, marine engineering, high-purity water treatment and other fields put forward more stringent requirements on material performance, traditional stainless steel materials can no longer be competent in some extreme corrosion environments for a long time. For this reason, super austenitic stainless steel tubes, as a type of high-alloy tubes with stronger corrosion resistance and higher pitting resistance, are being adopted and valued by more and more projects.

Jiangsu Jend Tube Co., Ltd. has been continuously cultivating in the field of stainless steel seamless tube production for many years. On the basis of conventional austenitic stainless steel tubes, it has further expanded the manufacturing capacity of super austenitic alloys, including 904L, UNS N08926, UNS N08367 (Alloy 625, etc.), 254SMO and other representative grades, providing solutions for global chemical, energy and water treatment projects.

Material properties of super austenitic stainless steel

Super austenitic stainless steel is a type of high-alloy stainless steel with significantly increased alloying element content in the austenitic matrix. It is characterized by much higher chromium (Cr), nickel (Ni), molybdenum (Mo) and nitrogen (N) content than conventional austenitic stainless steel. Copper (Cu) is also added to some materials to improve the ability to resist corrosion in reducing acid media.

Common grades and their characteristics include:

904L (UNS N08904): Contains 25% nickel and 4.5% molybdenum, and copper is added at the same time. It is mainly used to treat non-oxidizing acid environments such as sulfuric acid and phosphoric acid;

254SMO (UNS S31254): Contains up to 6% molybdenum and a higher nitrogen content. It has good performance in pitting and crevice corrosion resistance and is suitable for seawater and concentrated chloride environments;

Alloy 625 (UNS N06625): Although it belongs to a nickel-based alloy, it is also frequently used in super austenite. It is widely used in high temperature, high pressure and corrosive media.

These steels have a high PREN (pitting equivalent number). Super austenitic steels with PREN ≥ 40 are usually recommended for use in severe corrosion or special working conditions.

Manufacturing capabilities and process control of Jiangsu Jend Tube Co., Ltd.

As a tube company covering the entire production process, Jiangsu Jend Tube Co., Ltd. implements strict process control over the smelting, heat treatment, cold processing and inspection of super austenitic stainless steel tubes.

Its main manufacturing capabilities include:

Outer diameter range: 3.18mm ~ 406.4mm

Wall thickness range: 0.3mm ~ 20mm

Maximum single length: 25000mm (customizable according to the project)

Implementation standards: ASTM B677, B705, B423, EN 10216-5, GB/T 14976, etc.

In order to meet the composition and organizational requirements of high-alloy steel, the company adopts medium-frequency furnace + electroslag remelting process to ensure metallurgical purity; through the combination of multiple cold drawing and heat treatment processes, the dimensional accuracy and mechanical properties are controlled; the final product is subjected to a series of quality control processes such as pickling passivation, ultrasonic flaw detection, water pressure test and intergranular corrosion test to ensure service stability in harsh environments.

Main application areas and actual cases

Super austenitic stainless steel tubes are increasingly being used in the following fields due to their comprehensive performance:

Marine engineering and seawater desalination

In seawater desalination plants, evaporator, condenser and preheater tubes are often exposed to high-concentration chloride water. 254SMO and 904L are widely used in such systems because of their high molybdenum and nitrogen content, which have stronger pitting resistance.

Phosphate fertilizer, sulfuric acid and fertilizer industry

904L has strong resistance to sulfuric acid corrosion due to the addition of copper, and is particularly suitable for the storage and transportation of concentrated sulfuric acid under medium and low temperature conditions, condensers and heat exchange systems.

Flue gas desulfurization (FGD) system

The desulfurization device used in coal-fired power plants has extremely high requirements for the resistance of tubeline materials to chloride ion stress corrosion. Alloy 625, N08367 and other materials are widely used in circulating absorption towers and spray devices in FGD systems.

Ultrapure water system in pharmaceutical and electronic industries

For high-purity water delivery tubelines, the material must not only have corrosion resistance, but also high surface flatness and no pollutant precipitation. Such systems usually use 316L or 904L tubes that are polished inside and outside and pickled and passivated, and are produced in conjunction with oil-free clean processes.

Global supply and technical support capabilities

Jiangsu Jend Tube Co., Ltd.'s super austenitic stainless steel tube products are currently exported to many countries and regions such as Europe, America, Southeast Asia and the Middle East, and are widely used in large international EPC projects.

The company can provide:

Raw material composition certificate (Heat No.)

Third-party agency test report (such as TUV, SGS)

Import and export customs declaration materials and certificates of origin (CO, FORM E)

Technical data support such as process maps, press installation recommendations, storage and transportation specifications

The company's technical team can also recommend suitable steel selection options for customers or perform material adaptation analysis on existing drawings based on project application conditions.

Future development and challenges

As the industry develops towards extreme, clean and intensive development, the demand for the use of super austenitic stainless steel shows the following trends:

Increased customization: More companies have put forward requirements for high parameters, complex shapes and directional heat treatment;

Increased cost sensitivity: High alloy costs push designers to seek a more precise balance between performance and economy;

Increased certification compliance requirements: Especially in industries such as offshore engineering, nuclear power, and medicine, higher requirements are placed on product traceability and testing standards;

Cooperative application with duplex stainless steel: In some systems, super austenitic steel and duplex steel materials are used in combination to achieve a balanced configuration of cost and performance.

Jiangsu Jend Tube Co., Ltd. will continue to optimize materials and upgrade processes based on actual engineering conditions of customers to meet the challenges of globalized and diversified application scenarios.