Three-layered laminate composite using invar alloy and high-Mn steel for structural applications in spacecraft

초록

In this study, we design a three-layered clad alloy with low thermal expansion and high mechanical performance within the temperature range encountered in low Earth orbit (−150 to +100 °C) for potential application as a structural material in spacecraft and satellites. The clad alloy plates were fabricated via a clad teeming process, which is a solid–liquid bonding technique, using two austenitic ferrous alloys: Invar alloy to provide low a coefficient of thermal expansion (CTE) and lightweight high-Mn steel to reduce density and enhance strength and ductility. The cold-rolled and annealed clad plate with a stacking sequence of high-Mn steel/Invar alloy/high-Mn steel (HIH configuration) developed B2 Ni (Al, Mn, Fe) precipitates in the cladding interface region, suppressing local recrystallization and increasing strength beyond the expected values. The clad plate maintained ductility above 50% even at cryogenic temperatures below −50 °C because of high strain-hardening rates associated with active twinning-induced plasticity. The HIH clad alloy exhibited a strength–ductility balance of ∼52,749–75,752 MPa·% and a low CTE of ∼8.75 ppm/°C within the temperature range of −150 to +100 °C. In other words, this clad alloy demonstrates superior mechanical properties compared with austenitic stainless steel, while maintaining a CTE comparable to that of titanium alloy, both of which are widely used as structural materials in spacecraft.

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