Austenitic stainless steel exhibits non-magnetic properties and boasts exceptional resistance against corrosion. It excels in weldability, formability, fabricability, and ductility. This stainless steel variant upholds its corrosion resistance even in extreme temperatures, reaching as high as 1500°F. Its versatility makes it invaluable for applications requiring both low and high-temperature service. The following content are several type grade of stainless steel pipe and the chemical component and application of all kind of austentic stainless steel
Type 301: Offers high ductility for shaped products and quick hardening during mechanical work, boasting good weldability. Exhibits superior wear resistance and fatigue strength compared to 304.
Type 302: Shares the corrosion resistance of 304 but holds slightly higher strength due to added carbon content.
Type 303: Recognized as an easier-to-machine version of 304 by incorporating sulfur and phosphorus. Referred to as "A1" as per ISO 3506 standards.
Type 304/304L :The most common grade; the classic 18/8 stainless steel. Also referred to as "A2" in accordance with International Organization for Standardization ISO 3506.
Type 309: Demonstrates improved temperature resistance compared to 304.
Type 316/316L: The second most prevalent grade, particularly suitable for food and surgical stainless steel applications. The addition of molybdenum prevents specific types of corrosion. Known as "marine grade" due to heightened resistance to chloride corrosion in contrast to type 304. Commonly used in constructing nuclear reprocessing plants and prevalent in many stainless steel watches.
Type 321: Shares similarities with 304 but lowers the risk of weld decay by including titanium. Also, consider type 347, which incorporates niobium for desensitization during welding.
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Characteristics & Application
Free cutting steel
Basic steel grade. Use for general purpose steel for many applications in many fields
Oxidation resistance. Use in Chemical plant pipes and tubes, Radiant tubes, Thermocouple protection tubes
Seawater resistance. Use in Seawater desalination plant pipes
Corrosion resistance. Use in LNG plant pipes, Boilers, nuclear power and chemical industry pipes and tubes
lntergranular corrosion resistance
Pitting corrosion resistance. Use in Chemical tanker pipes
Intergranular corrosion resistance. Use in Chemical plant pipes
High-temperature strength. Use in Boiler heater tubes and reheater tubes
lntergranular corrosion resistance. Use in Chemical plant pipes and tubes
High-temperature strength. Use in Boiler heater tubes and reheater tubes
lntergranular corrosion resistance. Use in Urea reactor tubes
Ferritic stainless steel, being magnetic and high in carbon content, tends to be brittle and exhibits relatively lower corrosion resistance when compared to austenitic stainless steel. It remains non-hardenable through heat treatment but showcases robust resistance against chloride stress corrosion cracking.
Heat-resistant but exhibits poor corrosion resistance with 11% Chromium and 8% Nickel content.
Economical variant primarily used in automobile exhausts; ferritic in nature, composed of iron and chromium.
Notable for its ease of machining due to additional sulfur content.
Mainly used for decorative purposes such as automotive trim; a ferritic stainless steel featuring good formability but exhibiting reduced temperature and corrosion resistance.
Characteristics & Application
10.5-11.7 Cr 0.5 Ni
Automotive Exhaust Systems
Chloride corrosion resistance and stress corrosion crack resistance. Use in water heater pipes
Duplex stainless steels are a combination of austenitic and ferritic stainless steels, and are composed of chromium, molybdenum, nickel and other elements. Typical grades of duplex stainless steel pipe include 1Cr18Mn10Ni5Mo3N, 2101 and 2205.
UNS S31803 (SAF 2205):
This is the most widely used duplex stainless steel grade. It contains approximately 22% chromium, 5-6% nickel, and 3% molybdenum. UNS S31803 offers excellent corrosion resistance, high strength, and good weldability.
UNS S32205 (SAF 2205):
Similar to UNS S31803, UNS S32205 offers the same composition and properties. It provides high resistance to stress corrosion cracking, making it suitable for applications involving harsh environments and chloride-containing solutions.
UNS S32750 (SAF 2507):
This grade, also known as super duplex stainless steel, contains approximately 25% chromium, 7% nickel, and 4% molybdenum. UNS S32750 offers exceptional corrosion resistance, high strength, and excellent resistance to pitting and crevice corrosion. It is commonly used in offshore and marine environments, chemical processing plants, and desalination systems.
UNS S32760 (Zeron 100):
Another super duplex stainless steel grade, UNS S32760 contains higher amounts of chromium, nickel, and molybdenum compared to UNS S32750. It provides excellent corrosion resistance, high strength, and improved resistance to corrosion fatigue and erosion. UNS S32760 is often used in applications where superior corrosion resistance and mechanical properties are required.
UNS S31803 (SAF 2205)
22% chromium, 5-6% nickel, 3% molybdenum
Excellent corrosion resistance, high strength, good weldability
Chemical processing, oil and gas, pulp and paper, desalination
UNS S32205 (SAF 2205)
Similar to UNS S31803
High resistance to stress corrosion cracking, suitable for harsh environments and chloride-containing solutions
Similar applications as UNS S31803
UNS S32750 (SAF 2507)
25% chromium, 7% nickel, 4% molybdenum
Exceptional corrosion resistance, high strength, excellent resistance to pitting and crevice corrosion
Offshore, marine environments, chemical processing, desalination
UNS S32760 (Zeron 100)
Higher chromium, nickel, molybdenum than S32750
Excellent corrosion resistance, high strength, improved resistance to corrosion fatigue and erosion
Applications requiring superior corrosion resistance, better mechanical prop
Martensitic stainless steel pipe is a type of stainless steel pipe which contains a high carbon content and is typically used for applications requiring high strength and hardness.
High strength, hardness, and wear resistance
Valve components, pump parts, shafts
Good corrosion resistance, high hardness, moderate strength
Surgical instruments, cutlery, molds
15-17% chromium, 1.25-2.5% nickel
Good corrosion resistance, high strength, hardness
Aircraft components, fasteners, pump shafts
16-18% chromium, 0.95-1.20% carbon
Excellent hardness, wear resistance, corrosion resistance
Bearings, surgical instruments, cutting tools
To determine the most suitable steel grade for a specific environment, assess the conditions your final product will endure. Factors like extremely low pH, high stress, elevated temperatures, and crevice corrosion can detrimentally affect the performance of stainless steel. Austenitic series steels, such as the commonly used 316 and 304 alloys, maintain their strength, toughness, and corrosion resistance across a wide temperature spectrum.
The primary consideration for selecting austenitic stainless grades is their corrosion resistance. Type 316, fortified with molybdenum, even combats chloride ions commonly found in marine and chemical processing settings. Irrespective of the steel grade, a well-designed structure is the best defense against corrosion.
Stainless steel, containing 10–30% chromium as an alloying element, resists corrosion. The inclusion of nickel in austenitic grades provides superior toughness and ductility among stainless grades. Alloys rich in chromium, molybdenum, and nickel exhibit the highest corrosion resistance.
Apart from alloy content, consider the material's processing, which impacts its mechanical properties. Cooling duration at various temperatures and the overall cooling rate during steel production affect its overall quality.
While heat treatment increases the hardness of carbon steels, cold working operations like rolling, bending, or drawing at lower temperatures harden austenitic stainless steel. However, note that increased hardness due to cold working may decrease properties like elongation and impact resistance.
Austenitic stainless steel is available in various forms such as bar, wire, tube, pipe, sheet, and plate. Most products require additional shaping or machining for specific applications.
For instance, stainless steel tubing might need bending, coiling, machining, welding, or end forming. When machining processes like CNC machining are involved, select a machining rate that mitigates work hardening or opt for a "free-machining" grade containing sulfur.
During welding, embrittlement in the weld area is a concern. Opt for lower carbon grades like 304, 304L, or 316L to minimize carbide formation.
Designers often select stainless steel for its aesthetic appeal—be it a shiny, electropolished "bright" finish, a dull "pickled" finish, a specific RMS polished matte surface, or a light-absorbing black oxide coating. Austenitic stainless steel grades can adopt these finishes and commonly undergo passivation.
Customers might also require certification for application-specific specifications, such as ASTM standards for different industrial uses. These standards ensure compliance with technical specifications for chemical composition, heat treatment, and other attributes.
While high-performing austenitic stainless steels are initially more expensive, they prove worthwhile due to their corrosion resistance. Choosing a corrosion-resistant material suited to the application minimizes maintenance, downtime, and replacement expenses. Life-cycle costing methods enable a comprehensive comparison of different materials in terms of current and future costs.
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In essence, grade of stainless steel pipes epitomize the marriage of innovation and functionality. From the corrosion-resistant Austenitic to the robust Martensitic grades, each category offers a distinct set of attributes catering to diverse industries. The Duplex variety bridges the gap with a harmonious blend of strengths, while the Ferritic types excel in reliability.
What’s more, grade of stainless steel pipe is an important factor to consider when selecting a pipe for a particular application. The grade of stainless steel pipe should be chosen based on the chemical composition of the metal, the desired properties of the pipe, and the requirements of the application.
It is of utmost importance to seek the guidance of a professional expert when considering the selection of the appropriate grade of stainless steel pipe, particularly for new entrants in the stainless steel market. Foshan Vinmay Stainless Steel Co., Ltd. is your reliable source for expert advice and solutions regarding stainless steel pipes. Contact us today for your planing.