低结合强度下热轧钛-钢复合钢材高周疲劳性能研究

为研究钛-钢复合钢材的高周疲劳性能，对由2mm厚钛合金TA2和8mm厚结构钢Q355采用热轧复合工艺生产的钛-钢复合钢板进行了轴向高周疲劳试验，并通过标准拉伸试验、复合界面剪切试验得到其基本力学性能。基于试验结果，得到了钛-钢复合钢材在应力比为0.1下的疲劳S-N曲线，并与4部钢结构设计标准中针对传统结构钢材的疲劳设计曲线进行对比分析。试验结果表明：所研究的钛-钢复合钢板在拉伸试验过程中具有三阶段断裂模式；尽管剪切试验得到的复合界面结合强度较低，但其疲劳性能依然高于一般单金属结构钢材，使用现有结构钢材的疲劳设计曲线预测钛-钢复合钢材的疲劳寿命过于保守；疲劳强度与抗拉强度比值为0.7，介于钛材和钢材之间；低结合强度界面和结构钢层表面均是潜在的疲劳源，产生两种不同疲劳破坏模式。基于上述研究结果提出了适用于该类钛-钢复合钢材的S-N曲线，可为钛-钢复合钢材在结构工程领域的疲劳设计提供参考，并有利于促进其工程应用。

Research on high-cycle fatigue properties of hot rolled titanium-clad bimetallic steel with low bonding strength

To study the high cycle fatigue properties of titanium-clad (TC) bimetallic steel, axial high cycle fatigue tests were carried out on TC bimetallic steel (TA2+Q355) plate produced by the hot rolling process with a thickness of 2mm+8mm. The basic mechanical properties were obtained by the tensile coupon tests and bonding interface shear tests. Based on the test results, the fatigue S-N curve of TC bimetallic steel at a stress ratio of 0.1 was obtained, which was compared with the fatigue design curves of traditional steel structures in four steel structure design specifications. The experimental results show that the tensile performance of TC bimetallic steels studied in this paper has three-stage fracture mode during tensile coupon test. In addition, although the shear strength of the bonding interface obtained by the shear tests is low, the fatigue performance of TC bimetallic steels is much higher than that of common single-metal structural steels, and it is conservative to predict the fatigue life of TC bimetallic steel by using the fatigue design curves of existing structural steel. Besides, the ratio of fatigue limit to tensile strength is 0.7, which is between those of titanium and steel. The low bonding strength makes the interface and the surface of the structural steel easy to become the fatigue sources of fatigue test, resulting in two different fatigue failure modes. Finally, the S-N curve suitable for this kind of TC bimetallic steel was presented. The research results can provide a reference for the fatigue design of TC bimetallic steel in the field of structural engineering, and promote its engineering application.