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采用四点弯曲疲劳试验研究了应力比为-0.82和-1的含铌微合金钢SQ390的疲劳行为,对疲劳断口进行了SEM分析,用试验结果对Soderberg公式进行了验证。结果表明,试验钢的弯曲疲劳曲线呈直线形,两个应力比下的弯曲疲劳强度分别为275 MPa和256 MPa,疲劳裂纹均起源于试样表面。Soderberg公式对低合金钢四点弯曲疲劳试验结果非常适用。
The four-point bending fatigue test was used to study the fatigue behavior of niobium microalloyed steel SQ390 with stress ratio -0.82 and -1. The fatigue fracture was analyzed by SEM, and the Soderberg formula was verified by the experimental results. The results show that the bending fatigue curve of the test steel is linear, and the bending fatigue strength under the two stress ratios is 275 MPa and 256 MPa, respectively. The fatigue cracks originate from the surface of the specimen. The Soderberg formula is ideal for four-point bending fatigue tests on low-alloy steels.