Failure Cause of Rock Drill Bar Hammer for Marine Reef Crushing Operation

The rock drill bar hammer on a dredger serving in a dredging and rock breaking project in the South China Sea was worn to the safe service size after 20 h operation. The failure cause of the rock drill bar hammer was analyzed by macro and micro morphology observation, chemical composition analysis, microstructure observation, and hardness, tensile and impact performance testing. The results show that the rock drill bar hammer had obvious work hardening and corrosive wear, and the damaged surface mainly showed rusts, cutting furrows and fatigue spalling pits. The main cause for the rock drill bar hammer failure was the uneven structure, carbide precipitation, oxide inclusion caused by improper composition control and casting process design, as well as by the interaction of impact, wear and corrosion.