Sintering behavior of addictive boron in stainless steel via master sintering curves and microstructural verification using image processing

Abstract Adding boron to stainless steel for sintering affects the densification behavior and microstructure, including the formation of the precipitated phase. This study investigated the effects of boron on densification for sintering via master sintering curves and microstructural analysis based on image processing. Mixtures of different boron contents in stainless steel powder were employed. The in situ shrinkages during sintering were used to construct master sintering curves for each mixture. The densification behaviors were analyzed according to various aspects, including the apparent activation energy. The results confirmed greater densification with the addition of boron, which decreased the melting point. The microstructural evolution was considered because the precipitated phase, which included Cr x B y , reduced the mechanical strength. An image processing method was used to identify the formation of the precipitated phase in the microstructure based on the intensity difference. The algorithm of the image processing method was verified with an electron probe micro-analyzer. The effects of boron on sintering were then quantified according to the Cr x B y phase. The results confirmed the increased formation of the Cr x B y phase. The low intensity of the Cr x B y phase according to the image processing method was validated by X-ray diffraction and transmission electron microscopy.