高速铁路关键材料超长寿命疲劳断裂性能

Extra-long life fatigue behavior of key materials for high-speed railway

利用压电超声频率加速疲劳实验方法对钢轨钢、轴承钢及铝合金共7种高速铁路用材料进行测试。实验证明了超长寿命疲劳裂纹往往从材料内部夹杂生产的机制;而且,试件在超过107次、甚至109次应力循环后仍然继续发生破坏。由此可见,这些高速铁路材料并没有传统规范中所谓的疲劳极限,而只有疲劳强度。因此,只用107次循环以内的数据作为高速铁路材料疲劳设计的依据是危险的。

Seven kinds of material for high -speed railway including rail steel, bearing steel and aluminum alloy and others are tested with piezoelectric ultrasonic fatigue -acceleration method.The mechanism that extra-long life fatigue crack always initiates from the internal inclusion is thus confirmed by the test. Damages continue to come into being after over 107, even 109 stress cycles for the specimen. Therefore, there is no so-called fatigue limit in conventional criterion; instead there is only fatigue strength. Thus, it is risky to use any cut-off value within 107 cycles for material fatigue design for high speed railway.