Improving fracture toughness and hardness of Fe₂B in high boron white cast iron by chromium addition

The effect of chromium containing 0%, 0.49%, 1.02%, 2.1%, 3.2% (in wt.%) on the morphology, fracture toughness and micro-hardness property of Fe₂B in high boron white cast iron was investigated. The results indicated that, with an increase of chromium addition, the morphology of Fe₂B becomes larger and changes from the block to rod shape, its micro-hardness increases and the fracture toughness increases first and then decreases. Compared with the fracture toughness (3.8 MPa m^1/2) of Fe₂B without chromium addition, the toughness at 2.1 wt.% chromium addition can be improved by above one time, achieving 7.8 Mpa m^1/2, and the result was also qualitatively testified by the micro-cracks in Fe₂B based on scanning electron microscope micrographs.