Effect of Si content on the microstructure and durability of selective laser melting of Hastelloy X alloy

The microstructure and durability properties of two batches of Hastelloy X alloy laser selective melting samples, A (Si0.071 wt%) and B (Si 0.365 wt%), were studied. The results show that before the 815°C/105MPa endurance test, the carbides of batch A samples precipitated both at the grain boundaries and within the grains. The grain boundary precipitates were distributed in a chain, and the carbide type was M23C6 type carbide rich in Cr elements. , the carbides of batch B sample almost only precipitate continuously at the grain boundaries, and the carbide type is M6C carbide rich in Mo element. After the endurance test, there was no obvious change in the precipitates of batch A samples, while more needle-like precipitated phase MoSiW was produced in the crystals of batch B samples. In addition, the durability properties of batch A samples all meet the forging standards, while the durability plasticity of batch B samples is lower, with an average elongation of 6.4%, which is lower than the forging standards. The morphology, distribution and type of precipitation phases in Hastelloy Continuity affects the bonding force between grain boundaries and reduces the durability of the alloy.