A quantitative characterisation of porosity in a Cr-Mo sintered steel using image analysis

作者:Cipolloni Giulia; Menapace Cinzia; Cristofolini Ilaria; Molinari Alberto*
来源:Materials Characterization, 2014, 94: 58-68.
DOI:10.1016/j.matchar.2014.05.005

摘要

A systematic characterisation of the porosity in the bulk and surface regions of a sintered Cr-Mo low alloy steel was carried out using image analysis. Fractional porosity in the different regions varies, mainly due to the scatter of the maximum pore size. A higher porosity is found in the bulk region and lower porosity in the regions that contact the die surface during compaction. The maximum pore size is larger in the bulk region than in the surface layers. The large pores are more irregular. With increasing green density, both the fractional porosity and maximum pore size decrease. The fraction of load bearing section in the bulk and surface regions was calculated from fractional porosity and the shape factor of the pores and compared in the different regions. The load bearing section fraction and the maximum pore size were used to predict tensile and fatigue resistance for different densities. The data from the characterisation of the bulk images can predict tensile strength. For fatigue, where the crack nucleates in the surface regions, the use of bulk data underestimates the fatigue resistance.

  • 出版日期2014-8