The microanalysis results show that the inclusions in weld metals, welding residual stress, working stress,mechanical vibrating stress and electrochemical corrosion of metal caused the penetration corrosion fatigue cracks in weld metals and its heat affect zones of hydraulic turbine blades.

Under fatigue load and corrosion medium,corrosion fatigue crack appeared first at the bottom of thread which was the dangerous section part of the pin joint.

Research on fatigue crack growth behaviors of 16MnR steel at elevated temperature.;

Effects of residual stress on the delay of fatigue crack initiation in the mixed-mode stress field for aluminum alloys;

Application of neural networks to the evolution of fatigue cracks;

Using ultrasonic to inspect endurance crack in collar thread;

The article focuses on the aspects as follows: the analysis for reasons of endurance crack, the chemical composition analysis of roller material, the selection of base metal and electrodes for repairing, the determination of welding parameters, the pre heat and post heat trea.

This paper gives all-round analysis to the endurance crack in the hull structure and tells the main causes for such endurance crack for reference.