April_AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | A P R I L 2 0 2 0 2 2 COST-EFFECTIVE ALTERNATIVE TO TITANIUM FOR AIRCRAFT PARTS High-strength, corrosion-resistant steel is a cost-effective alternative to titanium alloys due to its high specific strength, high fatigue strength, good toughness, and corrosion resistance. Gregory Vartanov, Advanced Materials Development Corp., Toronto A ircraft landing gear and structur- al components, as well as tur- bomachinery components that are used at moderate temperatures, are regularly subjected to severe loading, corrosion, and adverse environmen- tal conditions. They also have complex shapes varying from thin to thick sec- tions. Materials such as high-strength titanium alloys and high-strength steels are widely used for these critical com- ponents. The main criteria for selecting these materials include their specif- ic strength (tensile strength to density ratio), fatigue strength, toughness, and corrosion resistance. High-strength titanium alloys Ti-6Al-4V, Ti-10V-2Fe-3Al, and Ti-5Al- 2Sn-2Zr-4Cr-4Mo are excellent candi- dates for use in critical components due to their high specific strength and fatigue strength, toughness, and excel- lent corrosion resistance. However, high cost along with machining issues limits application of these alloys. Near net shape (NNS) powder met- allurgy-based hot isostatic pressing (PM HIP) is well verified for numerous critical applications in aerospace and turbomachinery. This technique is con- sidered an advanced shaping and con- solidation process for manufacturing critical components from high-strength titanium alloys. This article proposes using a high- strength, corrosion-resistant steel (HSCR steel) as an alternative material for manufacturing critical aerospace and turbomachinery components. HSCR steel is a low-cost substitute for tita- nium alloys due to its high specific strength, high fatigue strength, good toughness, and corrosion resistance. ADVANTAGES OF HSCR STEEL HSCR steel [1] and high-strength ti- tanium alloys are both used in critical components, yet each has some ad- vantages as well as shortcomings. Pre- mium-quality HSCR steel ingots are produced by vacuum melting whereas HSCR steel powder is produced through atomization, including vacuum atom- ization. Critical components can be manufactured from HSCR steel by the following processes: 1. Hot working (HW) of premium- quality ingots by forging, rolling, and pressing, followed by machining and hardening. 2. Powder metallurgy-based, hot iso- static pressing to near net shapes, followed by finish machining and surface quality improvement, if necessary, and hardening. 3. Additive manufacturing (AM) fol- lowed by finish machining and sur- face quality improvement if neces- sary, along with heat treatment. 4. Casting, including precision in- vestment casting and vacuum casting, then hot isostatic pressing, followed by finish machining and surface quality improvement, if necessary, and hardening. Hardening of HSCR steel consists of austenitizing and rapid cooling, op- tional refrigerating, and tempering at