5th International High Manganese Steel Conference - HMNS 2022

Steels used in several aerospace applications, specifically landing gears, require high strength and fracture toughness, good ductility and corrosion resistance. However, currently used steels such as 300M and SAE 4340 are not corrosion resistant and therefore a coating is needed. Recently, a new non-toxic zinc-nickel coating is being developed; however, neither zinc-nickel coating nor chromium and toxic cadmium coatings do not solve the corrosion problem if it cracks. Ultimately, the use of stainless steel delivers a more robust solution, reducing maintenance time and cost of repairs caused by corrosion. Ultra high-strength stainless steels have been developed to replace the coated 300M and SAE 4340 steels. They are alloyed with Co (8-13 wt.%) and Ni (17-19 wt.%) and can be considered as maraging stainless steels. The high content of alloying elements and their complex production result in low viability of these maraging stainless steels. This paper presents the results of a newly developed high-strength low allowed maraging steel to be used in aerospace applications. The newly developed maraging steel (Fe-7Cr-7Mn-5Ni–3Mo-1Ti, wt.%) was produced by conventional steelmaking processes. Different heat treatments were carried out to determine the optimal parameters such as temperature, time, cooling rate to obtain a high strength properties. After quenching and tempering, the new material shows a martensitic microstructure. It presents yield and ultimate tensile strength higher than 1300 MPa and 1500 MPa, and hardness higher than 45 HRC. The Pitting Resistance Equivalent Number (PREN) is higher than 17. The newly developed X4CrMnNiMoTi7-7-5-3-1 maraging steel can be a new option to replace coated steels in aerospace applications due to the high mechanical strength.