Abstract This paper reports the results of a study into the effects of the composition, hardness and electrochemical properties of W-group cast irons on sand slurry-erosion resistance and wear mechanisms. The results indicate that the sand slurry-erosion resistance of the irons can be raised by increasing the content of tungsten, especially when the iron is alloyed with chromium. The relation between macrohardness and sand slurry-erosion is intricate. In the low hardness range, the sand slurry-erosion resistance is linearly increased with hardness, but this relationship does not exist in the high hardness range. The sand slurry-erosion resistance of cast iron can be considerably increased by increasing its corrosion resistance. Sand slurry-erosion is an abrasive wear process accompanied by corrosion and cavitation, all of which aggravate each other.