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 m1/2) of Fe2B without chromium addition, the toughness at 2.1 wt.% chromium addition can be improved by above one time, achieving 7.8 Mpa m1/2, and the result was also qualitatively testified by the micro-cracks in Fe2B based on scanning electron microscope micrographs.