温度对汽轮机转子用2CrMo合金钢高周疲劳性能的影响

Effect of Temperature on High-Cycle Fatigue Properties of 2CrMo Alloy Steel for Turbine Rotor

在室温和高温(450,500,566℃)下对某进口汽轮机转子用2CrMo合金钢进行了拉伸试验和轴向力控制的高周疲劳试验,基于试验数据得到该钢的高周疲劳应力-寿命曲线,并通过广义中值曲面模型得到了中值寿命曲面,研究了温度对高周疲劳性能的影响。结果表明:试验钢的屈服强度、抗拉强度和弹性模量随温度的升高而下降;相同应力水平下,高周疲劳寿命随温度的升高而下降,高应力比(0.5,0.8)下,高周疲劳寿命受应力水平影响较大。低应力比(-1,-0.3)下高周疲劳断口为典型的轴向承载高周疲劳断口,在高温时疲劳源呈多源特点,室温时为单一裂纹源;高应力比(0.5,0.8)下高周疲劳断口呈现拉伸断口特征,室温下断口存在明显的放射区、纤维区和剪切唇区,高温下只有纤维区和剪切唇区。

The tensile test and axial stress controlled high-cycle fatigue test were carried out on an imported 2 CrMo alloy steel for turbine rotor at room temperature and high temperature(450, 500, 566 ℃). The high-cycle fatigue stress-life curves of the steel were obtained based on test data, and curved surface of median life was obtained by generalized curved surface of median model. The effect of temperature on the high-cycle fatigue properties was studied. The results show that yield strength, tensile strength and elastic modulus decreased with increasing temperature. High-cycle fatigue life decreased with increasing temperature at the same stress level. The influence of stress level on fatigue life was great at high stress ratio(0.5,0.8). The high-cycle fatigue fracture under low stress ratio(-1,-0.3) was a typical high-cycle fatigue fracture under axial load;the fatigue source was multi-source at high temperature and a single crack source at room temperature. At high stress ratio(0.5,0.8), high-cycle fatigue fracture presented tensile fracture characteristics;fracture had obvious radial zone, fiber zone and shear lip zone at room temperature, and had only fiber zone and shear lip zone at high temperature.