Cause of Cracking on High-pressure Hose Tube Fitting for Hydraulic Excavator

The high-pressure hose tube fitting of a hydraulic excavator cracked in use. The causes of cracking of high-pressure hose tube fitting were analyzed by means of fracture analysis, chemical composition analysis, metallographic examination, hardness test and reproduction test. The results show that the martensite appeared in microstructure of the cracked hose tube fitting due to sudden cooling during the processing of heating bend tube, and the hydrogen embrittlement sensitivity of hose tube fitting increased because of the subsequent electroplating without dehydrogenation process. Finally, hydrogen induced delayed crack of the hose tube fitting occured under the action of working stress.