The efficient characterization of material properties of porous multi-phase sintered steels by instrumental indentation is still an open question. To the authors’ knowledge, so far only a characterization of single-phase porous sintered steel by nanoindenation has been reported in literature. This paper for the first time offers a study about the applicability of microindentation techniques for characterizing the matrix material in a multi-phase sintered steel. This preliminary study is motivated by the relatively wide availability of necessary equipment, and simplicity of material identification procedures.

Herein, a dual-phase ferrite/bainite Astaloy steel with 9% porosity is studied. Various commonly used methods for the reconstruction of stress–strain curves from microindentation data are considered, whereby both Vickers and spherical tips are used. In addition, some homogeneous solid materials are investigated to better asses the performance of applied identification procedures. Two approaches for the mesoscale identification of the considered sintered steel are attempted. The first one is based on the identification of individual material phases, while in the other one the homogenization of the metallic matrix is adopted. To assess the reliability of obtained parameters, the direct numerical simulation of representative volume elements of realistic steel microstructure subjected to uniaxial tension is conducted. Numerical results are compared with the data from the macroscopic uniaxial tensile test.

The obtained results indicate that microindentation is adequate for the identification of elastic properties of individual material phases, but results for local plastic parameters are largely inconclusive and a further analysis is needed, focusing on applying smaller forces and investigating the influence of pores on identification results. Nevertheless, it seems that macroscopic stress–strain curves could be captured more accurately by the methodology based on the matrix homogenization if relatively large indentation forces are applied.

通过仪器压痕有效表征多孔多相烧结钢的材料性能仍然是一个悬而未决的问题。据作者所知，迄今为止，文献中仅报道了通过纳米压痕表征单相多孔烧结钢。本文首次研究了微压痕技术在表征多相烧结钢基体材料方面的适用性。这项初步研究的动机是必要设备的相对广泛可用性和材料识别程序的简单性。

本文研究了一种孔隙率为 9% 的双相铁素体/贝氏体 Astaloy 钢。考虑了根据显微压痕数据重建应力-应变曲线的各种常用方法，其中使用了维氏和球形尖端。此外，还研究了一些均质固体材料，以更好地评估所应用的识别程序的性能。尝试了两种方法来对所考虑的烧结钢进行介观识别。第一个基于单个材料相的识别，而另一个则采用金属基体的均质化。为了评估所获得参数的可靠性，对受到单轴拉伸的真实钢微观结构的代表性体积单元进行了直接数值模拟。将数值结果与宏观单轴拉伸试验的数据进行比较。

所得结果表明，微压痕足以识别各个材料相的弹性特性，但局部塑性参数的结果在很大程度上是不确定的，需要进一步分析，重点是施加较小的力并研究孔隙对识别结果的影响。尽管如此，如果施加相对较大的压痕力，基于基体均质化的方法似乎可以更准确地捕获宏观应力-应变曲线。