Analysis of Broken Section of Connecting Rod

We make the stale analysis for the broken section of the connecting rod used on 105 diesel engine,the material was 45# steel,The broken section was divided into three parts.First,the fatigue area near the oil hole on the small side of the rod.Second,the expanding area of stable fatigue.Three,the final snap brokrn area.We made the major analysis with first and second areas by macro-section and scanning electric microscope.Finally we find the cause and have this question to be settled.