AM 355 Steel: Composition, Uses, and Machining
When it comes to high-performance materials in demanding industries, AM 355 steel stands out as a versatile and reliable choice.…
In the realm of advanced materials, AMS 5743 stainless steel, also known as AM 355, stands out as a versatile and high-performance alloy that is making significant waves across various industries. Renowned for its exceptional corrosion resistance, mechanical strength, and ease of fabrication, this stainless steel grade is increasingly favored in applications ranging from aerospace to medical devices. Understanding the unique composition and properties of AMS 5743 is crucial for engineers, manufacturers, and designers who seek to leverage its capabilities for innovative solutions. In this article, we will delve into the intricate details of AMS 5743, exploring its chemical makeup, key characteristics, and a wide range of applications that highlight its importance in modern engineering. Whether you’re looking to enhance your product designs or simply broaden your knowledge of advanced materials, this comprehensive guide will provide valuable insights into the world of AMS 5743 stainless steel.
AM 355, also known as Alloy 355, is a specialized stainless steel notable for its strength and excellent resistance to corrosion. This alloy’s main components, chromium, nickel, and molybdenum, give it its high-performance characteristics, making it suitable for demanding applications.
The unique properties of AM 355 make it ideal for high-performance sectors like aerospace and industrial manufacturing. Its ability to maintain strength and durability at elevated temperatures further enhances its applicability in critical components.
AM 355 is known for its high tensile and yield strengths, along with excellent corrosion resistance. This combination of strength and resistance allows AM 355 to outperform many conventional stainless steel grades, making it a robust choice for various applications.
The alloy is widely used in aerospace, particularly for components like gas turbine blades and rotors. It is also valuable in industrial tooling and other engineering applications due to its versatility and reliability.
In summary, AM 355 is a reliable material for applications that require both strength and resistance to harsh conditions, making it essential in modern engineering and manufacturing.
AM 355 is a high-performance stainless steel alloy known for its balanced composition of chromium, nickel, and molybdenum. This carefully engineered mix provides the alloy with its superior properties.
Carbon, ranging from 0.10% to 0.15%, enhances hardness and strength through solid solution strengthening and precipitation hardening. Manganese, at 0.50% to 1.25%, contributes to the alloy’s toughness and helps in deoxidizing during steel production. Silicon, present up to 0.50%, improves oxidation resistance and overall strength.
Phosphorus is limited to a maximum of 0.04% to prevent brittleness and maintain the alloy’s ductility. Low sulfur content, up to 0.03%, ensures good machinability and corrosion resistance.
Chromium, ranging from 15.00% to 16.00%, is essential for corrosion resistance and contributes to the formation of a protective oxide layer. Nickel, at 4.00% to 5.00%, enhances the alloy’s toughness and resistance to corrosion, particularly in acidic environments.
Molybdenum, present at 2.50% to 3.25%, enhances resistance to pitting and crevice corrosion, particularly in chloride-rich environments. Nitrogen, at 0.07% to 0.13%, improves strength and enhances corrosion resistance.
Overall, the precise balance of these elements makes AM 355 ideal for applications requiring high strength and excellent corrosion resistance, such as in the aerospace and industrial sectors.
Heat treatment is crucial for optimizing AM 355 stainless steel’s mechanical properties and performance for various applications. Different heat treatment methods enhance its strength, toughness, and corrosion resistance.
AM 355 is initially supplied in the annealed state, which offers excellent formability similar to other austenitic stainless steels. Annealing involves heating the material to a specific temperature and then slowly cooling it to relieve internal stresses and soften the metal.
The equalized and over-tempered condition involves a two-step process to enhance strength and corrosion resistance. First, the material is equalized by heating it to a high temperature to homogenize the microstructure. Over-tempering then reheats the alloy to a lower temperature, resulting in a balance of high tensile strength and good ductility.
This process involves cooling the material below zero degrees Celsius, typically with liquid nitrogen, followed by tempering. This treatment reduces the risk of intergranular corrosion and maintains high strength. It is particularly effective in preventing carbide precipitation at grain boundaries, which can compromise corrosion resistance.
The mechanical properties of AM 355 vary based on the heat treatment applied. These properties include yield strength, ultimate tensile strength, elongation, reduction of area, and hardness.
The yield strength of AM 355 can reach up to 155 ksi (1069 MPa) at 0.2% offset in the equalized and over-tempered condition. This high yield strength makes the alloy suitable for applications requiring significant load-bearing capacity.
AM 355 has an ultimate tensile strength of up to 170 ksi (1172 MPa) in the equalized and over-tempered condition. This property indicates the maximum stress the material can withstand before failure, making it ideal for high-stress environments.
Elongation, which measures the material’s ductility, typically ranges from 12% to 19% in 2 inches (50 mm), depending on test conditions. This indicates the alloy’s ability to deform plastically before fracturing.
Reduction of area measures the material’s ability to undergo significant deformation before failure, ranging from 25% to 57% based on test conditions. This property is critical for applications where toughness and resistance to brittle fracture are essential.
AM 355 can reach up to 48 HRC in Rockwell C hardness in the equalized and over-tempered condition. High hardness is beneficial for wear resistance, making the alloy suitable for cutting tools and other high-wear applications.
Heat treatment of AM 355 tailors its mechanical properties for specific applications, offering formability, strength, ductility, and corrosion resistance. These attributes make AM 355 ideal for demanding industrial and aerospace uses.
AM 355 is highly valued in the aerospace industry due to its exceptional strength, corrosion resistance, and ability to maintain performance at elevated temperatures.
AM 355 is commonly used to manufacture gas turbine parts like blades, discs, and rotors. These components operate under high stress and temperature conditions, where the alloy’s superior mechanical properties and heat resistance are crucial. The high tensile strength and corrosion resistance of AM 355 ensure long-term reliability and efficiency in these demanding applications.
AM 355 is also used in various shafts and structural elements within aerospace systems, benefiting from its strength and toughness to ensure durability and resistance to wear and fatigue. The material’s performance in high-temperature environments makes it suitable for critical aerospace applications where failure is not an option.
Beyond aerospace, AM 355 finds significant use in various industrial sectors requiring materials that can withstand harsh conditions and high stress.
AM 355 is an excellent choice for industrial cutters and knives because it stays sharp and resists wear. These tools require materials that maintain sharpness and structural integrity under repetitive use and abrasive conditions. The alloy’s ability to resist corrosion also extends the lifespan of cutting tools, reducing maintenance and replacement costs.
The alloy is also utilized in mechanical parts such as gears, valves, and other components exposed to corrosive environments and mechanical stress. Its combination of strength, toughness, and corrosion resistance makes AM 355 a reliable material for parts that face prolonged use and harsh conditions.
In the oil and gas industry, AM 355 is used for components that are exposed to aggressive environments, including high temperatures and corrosive substances.
Downhole tools in oil wells benefit from AM 355’s strength and corrosion resistance. These tools must withstand high pressures and corrosive fluids, making the alloy’s properties particularly valuable for ensuring operational efficiency and safety.
Valves and fittings in oil and gas extraction processes are often made from AM 355, ensuring reliable performance and longevity even with harsh chemicals and high pressures. This ensures reliable performance and longevity, even in the presence of harsh chemicals and high-pressure conditions.
The biocompatibility and corrosion resistance of AM 355 make it suitable for certain medical applications.
AM 355 is used to make surgical instruments that require high precision and reliability. The alloy’s ability to maintain sharp edges and resist corrosion from sterilization processes ensures the longevity and effectiveness of these tools.
In some cases, AM 355 is used for orthopedic implants that demand high strength and resistance to body fluids. The alloy’s mechanical properties and corrosion resistance ensure the durability and success of these implants.
The diverse applications of AM 355 across aerospace, industrial, oil and gas, and medical sectors highlight its versatility and superior performance characteristics. Its combination of high strength, excellent corrosion resistance, and heat resistance makes it ideal for components that must endure extreme conditions and rigorous use.
AM 355 stainless steel is renowned for its excellent corrosion resistance, thanks to its balanced chemical composition featuring high levels of chromium, nickel, and molybdenum. This unique combination makes it an ideal choice for environments that require both high strength and resistance to corrosive elements.
Compared to other quench-hardenable martensitic stainless steels, AM 355 exhibits significantly better corrosion resistance, primarily due to its higher chromium content, which enhances the formation of a protective oxide layer. While AM 355’s corrosion resistance is slightly less than that of chromium-nickel austenitic stainless steels, it still performs well in many environments where both corrosion resistance and high strength are needed.
AM 355 provides excellent resistance to atmospheric corrosion, making it suitable for outdoor applications exposed to the elements. In mildly corrosive chemical environments, including diluted acids and alkaline solutions, AM 355 withstands degradation effectively. The presence of molybdenum further enhances its resistance to pitting and crevice corrosion, particularly in chloride-rich areas.
In marine environments, AM 355 excels by enduring saltwater exposure that quickly corrodes lesser materials, ensuring durability in marine applications.
AM 355, particularly in the double-aged or equalized and over-tempered condition, can be susceptible to intergranular corrosion due to carbide precipitation at grain boundaries. To prevent this type of corrosion, a specific heat treatment involving sub-zero cooling can be employed. This treatment helps avoid carbide precipitation, thereby maintaining the alloy’s corrosion resistance.
The corrosion resistance of AM 355 is greatly influenced by its heat treatment. The recommended process includes heating to 1875/1900 °F (1024/1038 °C), followed by water quenching, sub-zero cooling, and tempering. This comprehensive treatment not only enhances mechanical properties but also reinforces resistance to intergranular corrosion.
Due to its excellent corrosion resistance and high strength, AM 355 is widely used in aerospace components, marine equipment, and chemical processing parts. These applications benefit from the material’s durability and reliability in demanding environments, making AM 355 a preferred choice for industries that require both performance and longevity.
AM 355, also known as AMS 5743, consists of the following elements:
The mechanical properties of AM 355 are influenced by heat treatment. Key properties include:
Yield Strength (0.2% offset) and Ultimate Tensile Strength:
At 850°F (454°C):
Yield Strength: 1255 MPa (L), 1276 MPa (T)
Ultimate Tensile Strength: 1489 MPa (L), 1517 MPa (T)
At 1000°F (538°C):
Yield Strength: 1179 MPa (L), 1165 MPa (T)
Ultimate Tensile Strength: 1276 MPa (L and T)
Elongation in 2 inches (%):
At 850°F (454°C): 19% (L), 12% (T)
At 1000°F (538°C): 19% (L), 15% (T)
Reduction of Area (%):
At 850°F (454°C): 38% (L), 21% (T)
At 1000°F (538°C): 57% (L), 40% (T)
The hardness of AM 355 should not exceed:
AM 355 can undergo various heat treatments to achieve desired properties:
AM 355 adheres to several important specifications:
AM 355 is versatile and available in various forms, including bar, sheet, plate, strip, forgings, and wire, making it suitable for different applications across various industries.
Machining AM 355 stainless steel requires careful consideration due to its work-hardening characteristics and toughness.
Machining in the annealed condition is not recommended due to the alloy’s high work hardening rate and tendency to be gummy. The best machinability is achieved in the equalized and over-tempered condition, where the material is more stable and easier to machine.
Tempering at around 1000 °F (538 °C) after sub-zero hardening can improve machinability by reducing hardness and work hardening.
Welding AM 355 stainless steel requires specific techniques to maintain its properties and ensure the integrity of the weld.
Depending on the application, post-weld heat treatment may be necessary to restore the material’s properties, particularly if welding has altered the microstructure. This typically involves annealing or tempering to relieve stresses and reduce brittleness.
Below are answers to some frequently asked questions:
The chemical composition of AM 355 stainless steel is as follows: Carbon (C) 0.10-0.15%, Manganese (Mn) 0.50-1.25%, Silicon (Si) up to 0.50%, Phosphorus (P) up to 0.04%, Sulfur (S) up to 0.03%, Chromium (Cr) 15.00-16.00%, Nickel (Ni) 4.00-5.00%, Molybdenum (Mo) 2.50-3.25%, and Nitrogen (N) 0.07-0.13%. The balance of the composition is primarily iron (Fe). This composition ensures the alloy’s properties, including high strength at moderately elevated temperatures and superior corrosion resistance compared to other quench-hardenable martensitic stainless steels.
AM 355 stainless steel can be heat-treated through various methods to achieve different properties. The primary heat treatment processes for AM 355 include annealing, hardening and tempering, and double aging.
Annealing involves heating the material to 1850-1950°F (1009-1066°C) followed by rapid quenching, which relieves internal stresses and enhances machinability and formability. For hardening and tempering, the material is heated to 1875-1900°F (1024-1038°C), water quenched, cooled to -100°F (-73°C) for at least 3 hours, reheated to 1700°F (927°C), air-cooled, and then sub-zero cooled again to -100°F (-73°C) for 3 hours. Finally, it is tempered at either 850°F (454°C) for maximum strength or 1000°F (538°C) for maximum corrosion resistance and toughness.
In double aging, the material is heated to 1375-1475°F (732-801°C) for 3-4 hours, rapidly cooled, then treated at 1000-1100°F (538-593°C) and air-cooled. This process imparts higher ductility and lower hardness, making the alloy more machinable. For AMS 5743 specifications, the heat treatment typically includes annealing, sub-zero cooling, equalizing, and over-tempering, following specific temperature and cooling protocols to optimize the material’s properties for various applications.
The mechanical properties of AM 355 stainless steel include a minimum tensile strength of 170 ksi (1172 MPa) and a yield strength at 0.2% offset of at least 155 ksi (1069 MPa). It exhibits a minimum elongation of 12% in 4D and a reduction of area of at least 25%. In terms of hardness, it can reach up to 48 Rockwell C at 850°F (454°C), with specific hardness limits depending on the diameter of the material. At elevated temperatures, such as 850°F (454°C) and 1000°F (538°C), the yield strength and ultimate tensile strength remain significant, indicating good performance under heat. Additionally, AM 355 demonstrates sufficient ductility for limited forming and has optimal machinability when in the equalized and overtempered condition.
AM 355 stainless steel is commonly used in a variety of demanding applications, including gas turbine components like blades, discs, rotors, and shafts, where high strength at elevated temperatures is essential. It is also suitable for structural and marine applications due to its corrosion resistance, making it ideal for environments exposed to harsh conditions. In the chemical processing industry, AM 355 is valued for its superior resistance to corrosion. Additionally, it is utilized in the manufacture of cutting tools and blades, motor shafts, and various industrial rotors and shafts, highlighting its versatility and durability.
AM 355 stainless steel, also known as Alloy 355, offers superior corrosion resistance compared to other quench-hardenable martensitic stainless steels. Its corrosion resistance is comparable to that of chromium-nickel austenitic stainless steels, providing good resistance to atmospheric and mild chemical environments. However, its corrosion resistance can be influenced by heat treatment conditions; while double-aged or overtempered conditions may lead to intergranular corrosion, sub-zero cooling can prevent such issues. Additionally, appropriate heat treatment, such as tempering at temperatures of at least 950°F, significantly enhances its resistance to stress corrosion cracking. Therefore, AM 355 is a preferred choice for applications requiring both high strength and excellent corrosion resistance, such as in gas turbine components and aerospace applications.
The specifications (AMS numbers) for AM 355 stainless steel are AMS 5547, AMS 5549, AMS 5743, and AMS 5744. AMS 5547 covers AM 355 in the form of sheet and strip, AMS 5549 covers it in the form of plate, AMS 5743 covers it in the form of bars and forgings, and AMS 5744 similarly covers bars and forgings. These specifications guide the various forms and applications of the material, particularly for corrosion and heat-resistant uses.
