The role of boron content in high alloy white cast iron (Ni-Hard 4) on microstructure, mechanical properties and wear resistance

• Ni-Hard 4 alloys with different boron additions were cast.
• Specimens were austenitized at 850 °C for 5 h, quenched in air and tempered at 250 °C for 4 h.
• Boron concentration in the alloy caused an increase in the amount of carbide.
• Addition of boron increased hardness and wear resistance of the material.
• Increasing boron content decreased toughness.

High alloy white cast iron materials (Ni-Hard 4/ASTM A532) are widely used in cement, concrete and mining industries due to high wear resistance. In this study, the effect of boron on the microstructure, mechanical properties and wear resistance in white cast iron containing different contents of boron was investigated. For this purpose, ferro-boron was used during cast that boron will occur with the contents of 0.26%, 0.37%, 0.49% and 0.55% in the material. Specimens were austenitized at 850 °C for 5 h, quenched in air and tempered at 250 °C for 4 h. Wear tests were carried out using a pin-on-disc tribometer under dry sliding conditions. Three-point bending tests were performed to determine the toughness properties. Microstructure, fracture and worn surfaces were investigated with scanning electron microscope. The results show that amount of carbide increases as boron content increases. This situation provides positive contribution on materials hardness and wear resistance. Toughness properties decrease as the boron content increases.