Structural steels include 4130, 4140, 4340, 300M, and Hy-Tuf, primarily used in front and rear landing gear. Stainless steels include 301, 302, 303, 321, 17-4PH, and 17-7PH, primarily used in engine nacelles, pylons, and thrust reversers, with smaller amounts also found in various parts of the fuselage.
4130 offers excellent hardenability and overall mechanical properties, excellent machinability and weldability, and good low-temperature impact toughness. It is used in a wide variety of aircraft, including thin and thick plates, bars, and tubes, and is suitable for manufacturing bushings, shafts, fasteners, and more.
4140 structural steel offers excellent hardenability and overall mechanical properties, excellent machinability and weldability, and good low-temperature impact toughness. It is primarily used in the fuselage, landing gear, pylons, and some fasteners.
4340 steel is a medium-carbon, low-alloy, high-strength steel, a typical example of low-alloy, ultra-high-strength steel. It exhibits excellent hardenability, a good balance of strength and toughness, high fatigue strength, low notch sensitivity, high low-temperature impact toughness, and no significant temper brittleness. Its primary use in aircraft is as bar steel. It is used to manufacture components such as the main shock absorber outer cylinder, piston rod, bushing, and the nose landing gear retraction and extension actuator cylinder. It is second only to 300M steel in load-bearing properties. Research on 4340 steel began in the United States in the mid-1940s. By lowering the tempering temperature, the steel’s tensile strength reached 1600-1900 MPa. 4340 steel began to be used in the F-104 aircraft landing gear in 1955.
300M steel is a medium-carbon, low-alloy, ultra-high-strength steel. It boasts high hardenability, temper resistance, and ultra-high strength, along with excellent transverse ductility, fracture toughness, fatigue resistance, and stress corrosion resistance. It is suitable for manufacturing structural components such as aircraft landing gear, airframe parts, joints, and shafts. It is a critical load-bearing component and is therefore used extensively. Since 1966, 300M steel has been widely used in landing gear for US military and major civil aircraft. Military fighter jets such as the F-15, F-16, DC-10, and MD-11 all utilize 300M steel. Furthermore, 300M steel is used in the landing gear of civilian aircraft such as the Boeing 747, as well as in the flap rails and slat ducts of the Boeing 767’s wings.
Hy-Tuf steel is also a low-alloy, high-strength steel, primarily used in components such as the outer tube and piston rod of the nose landing gear, as well as the front mounting bracket and front strut of the engine pylon.
301 is a type 18-8 austenitic stainless steel with excellent oxidation resistance, high-temperature creep strength, and cold formability. It is used in aircraft fuselage components such as panels, reinforcements, and backing plates in areas where the ambient temperature is too high compared to aluminum alloys.
302 is also a type 18-8 austenitic stainless steel. In addition to the characteristics of 301, it has better corrosion resistance and is primarily used in areas where the ambient temperature is too high compared to aluminum alloys.
303 is a type 18-8 austenitic stainless steel with S and Si added to improve machinability, but its corrosion resistance is inferior to that of 302. It is primarily used in the manufacture of high-temperature nuts, screws, and tees.
321 is an austenitic stainless steel that cannot be heat-treated and strengthened. It has good resistance to intergranular corrosion and is used in slip rings, exhaust pipes, high-temperature chemical processing equipment, and pressure vessels.
17-4PH is a martensitic precipitation-hardening stainless steel with excellent casting properties. It is primarily used for medium-temperature load-bearing components and precision castings in engine thrust reversers, such as reinforcement plates, brackets, and joints.
17-7PH is a semi-austenitic precipitation-hardening stainless steel with high ductility in the annealed state. It can achieve high strength through appropriate heat treatment or cold working. It is primarily used for medium-temperature load-bearing components and engine thrust reverser components, valve diaphragms, and various stainless steel elastic elements. It is also widely used internationally in thin-walled aircraft structural parts, various vessels, ducts, springs, and compressor discs.
Cherry
Website: www.jinyoumetal.com
Email: Cherry@jinyoumetal.com
WhatsApp/WeChat: +86 13373795593
#Structuralsteels #SS301 #SS17-4PH
