Effect of Silicon on Precipitates of High-Silicon Austenitic Stainless Steel

The effect of silicon contents (4wt%similar to 8wt%) on microstructure of high-silicon austenitic stainless steel ZeCor was investigated by XRD, TEM and indentation deformation. Results show that increasing Si content leads to the phase constitute change of ZeCor alloy: the microstructure is single-phase austenite (gamma phase) in ZeCor-4wt%Si alloy, gamma phase with a small quantity of sigma-phase in ZeCor-6wt%Si alloy, and as for the ZeCor-8wt%Si alloy, the main precipitations are Cr3Ni5Si2 phase and a bit sigma-phases. In addition, the Cr3Ni5Si2 phase has a higher silicon and nickel content than the sigma-phase. The Cr3Ni5Si2 phase with a micro-hardness HV as high as 7840 MPa is a typical hard and brittle phase, and the precipitation of such phase can greatly increase the micro-hardness of the. matrix in the ZeCor-8wt% Si alloy. The strengthening mechanism of. matrix in ZeCor alloy is as follows: the solid solution strengthening is the main strengthening mechanism in ZeCor-6wt% Si alloy, while the solid solution strengthening of Si and the precipitation strengthening of Cr3Ni5Si2 greatly increase the micro-hardness of the. matrix in ZeCor-8wt%Si alloy, and the Cr3Ni5Si2 phases have a great effect.

Automated summary

The effect of silicon contents (4wt% to 8wt%) on the microstructure of high-silicon austenitic stainless steel ZeCor was investigated. The results showed that increasing Si content leads to a phase constitute change in the ZeCor alloy. The precipitation of Cr3Ni5Si2 phase greatly affects the micro-hardness of the matrix in the ZeCor-8wt%Si alloy.