FATIGUE CRACK GROWTH RATE TESTS OF HIGH PERFORMANCE STEEL HPS 485W FOR BRIDGES

This paper is about the research of Chinese high performance steel HPS 485W for bridge engineering.Under fatigue load ratio of R=0.1,R=0.5 and R=0.8,fatigue crack growth rate (da/dN) tests were conducted for HPS 485W compact specimens with thickness of 7.5mm,12.5mm and 19.5mm,respectively.The seven-point incremental polynomial method was adopted for local fitting to obtain fatigue crack growth rate.The tested HPS 485W has better crack growth resistance compared with traditional bridge steel 14MnNb.The test result shows specimen thickness is an influencing factor for crack growth rate,and fatigue crack growth rate increases with the increase of fatigue load ratio R.Furthermore,for 19.5mm HPS 485W specimen under fatigue load with R=0.1,the engineering threshold was tested and numerical calculation was conducted to obtain theoretical threshold.The calculated theoretical threshold is 7.22MPa·m^1/2.The fatigue crack growth rate curves obtained can be used for fatigue design,fracture control,and life prediction for high performance steel bridge.