Abstract: In view of new material 36MnVS4 with higher fatigue strength, the fracture splitting performance of the connecting rod was studied in comparison with C70S6, and reason of the fracture splitting defects was analyzed. In term of the brittle cleavage fracture feature of the new material mode I crack, the K criterion and the maximal principal stress failure criterion were determined. Meanwhile, the splitting Finite Element Model (FEM) of connecting rod was established with starting notch. By observing the stress concentration zone and the deformation distribution of the fracture splitting process, the crack initial position and time of the connecting rod and the plastic deformation of the notch and big-end in fracture surface were acquired. Considering the crack propagation velocity and the cracking load, the main defects were investigated and the fracture mass was evaluated. Results show that, under the same geometrical parameters and load, compared with the C70S6, the 36MnVS4 connecting rod production has more defects in the fracture splitting process because that the initial position of the crack is scattered, the crack propagation is instable, the notch sensitivity is high and there are more ferrites. However, the new material has a lower out-of-rounding as big-end hole and a smaller fracture surface plastic deformation after the fracture splitting.

Key words: materials systhesis and processing technology, 36MnVS4, connecting rod, fracture splitting, numerical simulation