Effect of WC content on porosity percentage, microstructure, and mechanical behavior of steel foam manufactured through powder metallurgy using space holder technique

In this present work, steel foams were successfully manufactured through powder metallurgy route using urea granules as space holder and influences of WC content (0, 0.5, 1, 2, and 4 wt. %) added into cell walls were studied on porosity percentage, microstructure of cell walls, and mechanical properties of steel foams. The microstructure of cell walls was evaluated using optical microscope and scanning electron microscope equipped with image processing software. Increasing WC has little effect on surface fraction and sphericity of cell, while the surface fraction and sphericity of the pores formed into the cell walls are strongly affected by the addition of WC. The mechanical behavior of the steel foams was conducted using compression test. The porosity of the steel foams is between 73 % and 80 % and with the increase in WC content, the porosity percentage decreases. The results of microscopic evaluations indicated that the microstructure of cell walls contains ferrite and pearlite, with tungsten carbide particles distributed uniformly. The stress vs. strain curves of the steel foam have an elastic region, a long saw-tooth plateau region, and a fracture point and the curves are shifted upward as the WC content increased.