On the Fatigue Performance of Nanoparticles Reinforced Iron by Selective Laser Melting

Selective laser melting (SLM) is an additive manufacturing process that uses laser beam to melt metal powders and allow the melt to solidify in a layerwise way. SLM has drawn much attention from industry and academia in recent years. Improving the mechanical properties and performance of components fabricated by SLM has been a focused research area. Adding hard second phase particles into metal matrix has been proven an effective measure to strengthen metal material by SLM. In this research, we adopt nano sized TiC particles to reinforce pure iron matrix using the SLM process. The reinforced TiC/iron composite with 0.5 wt.% TiC is successfully fabricated. Tensile tests and fatigue tests are carried out to demonstrate the strengthening effect, and fatigue fracture surfaces are characterized by SEM to understand the fatigue failure mechanism. The obtained experimental data are compared with an existing composite fatigue life prediction model. The results indicate that nano TiC is effective in improving the tensile performance of pure iron, where the ultimate tensile strength (UTS) and yield strength (YS) increase by 17% and 6.3% respectively. TiC nano particles improve the fatigue life principally at lower cycle fatigue regime, while the beneficial effect at high cycle fatigue regime is not significant, mainly due to the large porosity introduced in SLM process. In addition, it is discovered that traditional Ding’s model does not accurately predict the fatigue life of nano TiC/iron composite, and thus more accurate fatigue modeling work is called for.