材料期刊网

采用压力容器用16MnR热轧钢不同缺口尺寸、不同厚度的紧凑拉伸 (CT)试样, 进行了不同温度、不同应力比条件的一系列疲劳裂纹扩展实验, 得到了相应实验条件下的疲劳裂纹扩展速率. 讨论了高温环境、缺口半径、应力比及试样厚度对疲劳裂纹扩展行为的影响规律. 结果表明: 16MnR钢在环境温度为150和300 ℃时的疲劳裂纹扩展速率比25和425 ℃时低, 300℃时疲劳裂纹扩展速率最低, 300℃以上时随温度的升高裂纹扩展速率增大; 缺口半径的大小对初期疲劳裂纹扩展有较大的影响; 应力比对16MnR钢的疲劳裂纹扩展行为没有影响; 疲劳裂纹扩展速率随试样厚度的增大而增大.

16MnR steel is a most widely used material for pressure vessels. The study on fatigue is very important for safety and fatigue life assessment of pressure vessels. Several experimental researches for fatigue of 16MnR steel were conducted and test data have been gotten, but it was short of fatigue study of the material under various conditions at present. The fatigue crack growth tests of 16MnR hot--rolling steel were carried out at different< temperatures and R--ratios with compact tension (CT) specimens in this paper. Different sized circular notches at the tip of the slot ranging from very sharp< to blunt were used in the CT specimens and the radii of the notches were 0.1, 1 and 2 mm, and the thicknesses of CT specimens were 3.8, 12.5, 18 and 25 mm, respectively. The fatigue crack growth performances were obtained. The effects of temperatures, notch sizes, R--ratios and specimen thickness on fatigue crack growth behaviors were studied. It was shown that the fatigue crack growth rates at 150 and 300 ℃ were lower than those at 25 and 425 ℃, the lowest one was at 300 ℃ and the crack growth rate increased with temperature above 300 ℃. The great influence of notch sizes on the fatigue crack growth rate was observed at early stage of crack growth only. The results also indicated that fatigue crack growth rate increased as the specimen thickness increased, but the fatigue crack growth rate of 16MnR steel was insensitive to the R--ratios.