It is well known that adding small amounts of Ti and B into aluminium casting alloys increase the fluidity, feedability, strength, fatigue resistance and pressure tightness. These occur because of Ti and B within the master alloys create heterogeneous nucleation sites by forming such intermetallic compounds as TiB 2 , Al 3 Ti and AlB 2. It is also known that the solidification time is influential on the formation of final grain size of aluminium cast parts. However the combining effects of both grain refining and solidification time has not been studied properly. Therefore, in this work, the effects of the grain refining and solidification time have been investigated on a sand-cast Al-4wt%Cu alloy. To determine solidification time effect, a tests mould having different section thickness has been used.
In SLM, a high energy density is applied by a laser to locally melt layers of metallic powder particles in order to create functional parts. This high energy intensity and additive process character create a specific/unique microstructure. The solidified melt pools in HSS M2 SLM parts are observed to consist of two distinct zones next to the heat affected zone. The first zone, at the bottom of the melt pool, consists of very fine cells and columnar dendrites and has a hardness of 655±80Hv0.1. The other zone contains acicular martensite and has a hardness of 859±80Hv0.1 which is already similar to the hardness of conventionally produced and heat treated HSS M2. Furthermore, the relative amount of these two zones is observed to be dependent on the scan velocity of the laser and hence can be controlled during the SLM process.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.