A study of the effect of Ti-Al-V microalloying on the mechanical and physical properties of invar 36

Abstract

In this study, the effect of the addition of the Ti-Al-V triple refiner to invar 36 on the mechanical and physical properties was studied in detail. In addition, the shielding of electromagnetic interference (EMI) performance was investigated in range of X-band (8 – 12 GHz). The maximum hardness and tensile strength of the refiner-treated sample were obtained 195 HV5 and 611 MPa, respectively, while the average grain size was reduced from 100 µm to 40 µm. Mechanical features such as hardness and tensile strength were improved with the Ti-Al-V triple refiner and hot forging processes due to grain boundary strengthening. The minimum coefficient of thermal expansion (CTE) was 1.14 ×10−6/°C at 20 – 100 °C for the hot-forged plain invar alloy. The grain/twin boundaries and residual stresses formed after forging inhibit lattice vibrations, which are naturally responsible for thermal expansion of solids. The EMI shielding performance of invar 36 was analyzed in range of ∼-55 to ∼-65 dB for the 1 mm thick sheet through 8 – 12 GHz.