Study on the microstructure and properties of WC-12Co cemented carbide fabricated by selective laser melting

Abstract

In this study, WC-12Co cemented carbides were fabricated by selective laser melting (SLM) and subsequently subjected to sintering. Effects of the scanning speed on the microstructure, mechanical properties and friction and wear performance of the prepared WC-12Co cemented carbides were investigated. Based on the XRD spectra, η phase appeared after the SLM process, confirming a loss of carbon during the preparation of WC-12Co. The WC average grain size increased with improving the scanning speed, which fluctuated in the range of 1.5 μm–2.5 μm. The relatively small WC average grain size was associated with the lamellar structure (alternating layers of coarse and fine WC grains) caused by the uneven temperature distribution of SLM. Co evaporation was quantitatively revealed by EBSD phase maps. Relationships between hardness, transverse rupture strength (TRS) and scanning speeds were analyzed. The comprehensive performance of the samples reached the best at the scanning speed of 400 mm/s, which the hardness, TRS was 81 HRA, and 650 MPa, respectively. Furthermore, after process optimization, the friction and wear properties of the material were tested, the friction coefficient was about 0.2 at room temperature, while 0.5–0.7 at 200°C–600°C.

Keywords

• Selective laser melting
• Cemented carbide
• Microstructure
• Transverse rupture strength