Temperature Measurements in Powder-Bed Electron Beam Additive Manufacturing

Abstract

Thermal characteristics such as process temperatures and melt pool sizes offer important information in metal additive manufacturing (AM) technologies such as powder-bed electron beam additive manufacturing (EBAM). In this study, a near infrared (NIR) thermal imager was employed to acquire build surface process temperatures during EBAM fabrications using Ti-6Al-4V powder. Challenges in NIR temperature measurements for EBAM were tackled including compensating temperatures due to the transmission loss and estimating the emissivity of Ti-6Al-4V in its molten state. At a beam speed of about 728 mm/s, a beam current of about 7.2 mA and a diameter of 0.55 mm, the maximum process temperature is on the order of around 2700 °C, and the melt pools have dimensions of about 2.72 mm and 0.72 mm in length and width, respectively.