*Article* **Mechanical Properties of Low Carbon Alloy Steel with Consideration of Prior Fatigue and Plastic Damages**

**Qing Liu 1, Zhanzhan Tang 1,\*, Xuan Yang 1, Zhixiang He 1, Hanyang Xue <sup>1</sup> and Hanqing Zhuge <sup>2</sup>**


**Abstract:** Mechanical properties, including the fatigue behavior of metals, are usually determined from damage-free specimens, but it is not well known how these properties change with respect to prior damages; hence, the present work aims to understand the remaining mechanical properties of low carbon alloy steel Q345q with pre-damages. Low-cycle fatigue tests on the damage free specimens, tensile tests on the low-cycle fatigue damaged specimens, and fatigue tests on the plastic deformed specimens were carried out, respectively. The low-cycle fatigue life prediction formula was proposed. The influences of different kinds of pre-damages on the residual mechanical properties were analyzed. Results show that the stable hysteretic loops in the low-cycle fatigue tests are wellstacked. The material illustrates Masing behavior, and it has a good energy dissipation capacity. The ductility of the low-cycle fatigue-damaged materials decreases significantly in comparison with the undamaged ones. The low-cycle fatigue lives of Q345q steel are almost unaffected, so long as the pre-applied tensile strain is lower than 10%.

**Keywords:** plastic deformation; low-cycle fatigue; mechanical properties; pre-damage; low alloy steel; coupling damage
