Fracture Analysis of 20CrNi3 Shank Adapter for Hydraulic Rock Drill
The 20CrNi3 shank adapter for hydraulic rock drill was fractured after drilling for 300 meters.The fracture causes of 20CrNi3 shank adapter were analyzed through chemical composition analysis,frac-ture morphology and microstructure observation,mechanical properties testing.The results showed that the composition,impact performance,hardness and hardened layer thickness of the 20CrNi3 shank adapter all met the technical requirements.The fracture surface of the shank adapter was macroscopic brittle fatigue fracture,and the main reason for the facture was that the quenching temperature of the carburized part was too high,resulting in the high residual austenite content in the carburized layer.During processing and use,further martensitic transformation occured,resulting in significant residual stress and phase transfor-mation instability.The fatigue resistance of the 20CrNi3 shank adapter was reduced,and fatigue fracture occured during use.By reducing the quenching temperature or adding cryogenic treatment could reduce the residual austenite content in the carburized layer,which was beneficial for improving the fatigue resistance of the 20CrNi3 shank adapter.An acceptance standard for the microstructure of 20CrNi3 shank adapter could be formulated to ensure product quality.
hydraulic rock drillshank adapterfailure analysiscarburizationresidual austenite
万方数据
维普
