中文摘要：

对1000 MPa级双相钢板进行了一系列疲劳试验，并对试验数据进行拟合处理，得出了双相钢的疲劳寿命经验公式，然后对疲劳断口进行了扫描分析。最终发现：在加载频率为8 Hz的拉-拉疲劳试验条件下，DP1000钢板的疲劳极限是680 MPa；双相钢的疲劳断裂主要是主裂纹扩展到一定程度后失稳断裂，二次裂纹萌生但未形成扩展。钢板的疲劳裂纹源与扩展区有明显的韧性断裂特征，瞬断区失稳发生脆性断裂。

英文摘要：

High cycle fatigue experiment was conducted on DP 1000 steel plate , the fatigue test data were fitted and obtaining the fatigue life experience formula of DP steel .The microstructure of the steel＇s fatigue fracture was analyzed by means of SEM .The results show that under the conditions of the loading frequency for 8 Hz, the fatigue limit of DP1000 steel plate is 680 MPa.Fatigue fracture of the dual phase steel is mainly that instability fracture occurres when the main crack grows to a certain degree , secondary crack initiates but does not propagate . Fatigue crack source and fatigue area of the dual phase steel have obvious ductile fracture characteristics , and transient breaking area instabilizes and occurs brittle fracture .