| Abstract:510L steel, microstructure of which is mainly composed of ferrite and pearlite, is a kind of traditional high strength steel (CHSS). DP600steel whose processing formability is better than510L steel, is a kind of advanced high strength steels (AHSS). Its microstructure is consist of ferrite and martensite.510L and DP600are all conventional wheel steel. As the probability of fatigue failure is highest among all failure behaviors, the present paper conducted series of microstructure and performance tests and studies, with the aim of investigating the main reason for fatigue failure of510L and DP600wheel steel. The main conclusions are as follows:(1) Type, morphology and distribution of inclusions impact on fatigue property of510L wheel steel significantly. Al2O3brittle inclusions with sharp corners for which degeneration processing being not sufficient, are easy to cause fatigue failure within the critical size of inclusions. Spherical half plastic calcium aluminate inclusions are not easy to cause fatigue failure.(2) In DP600wheel steel, the relationship between fatigue life N and amplitude stress Se (R=-1) under stress cycling at room temperature accords with loglog linear relationship:lg(Se)=-0.1091g(N)+3.1590. Fatigue strength under R=0.1is370MPa by staircase method, which is in accordance with calculation result370MPa by the above loglog linear relationship.(3) Shape of inclusions impact on fatigue property of DP600wheel steel significantly. Strip aluminum silicate inclusions are main reasons for fatigue failure of DP600wheel steel.(4) Fractal dimension calculation indicates that when Ca content is between11.6-23.4wt%in calcium aluminate inclusions,1D can be controlled within1.10. Inclusion edge smooth and is beneficial to improve fatigue performance. |
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