harden quench
2.The results of experiments indicate that adding micro-amount of boron or a proper quantity of copper to the composite cast iron can increase its quench-harden-ing ability, a needle-like matrix composed of martensite or bainite can be obtained in the center of a Φ126mm grinding ball, and make hardness and impact toughness of the composite cast iron increased, the hardness is 50- 55 HRC, the toughness is 6-10J/cm2.
