电熔增材制造16MND5钢的低周疲劳特性

摘要：电熔增材是一种新型重型金属3D打印技术，使用该技术制造的16MND5钢是一种新型材料，对其低周疲劳特性进行系统研究，对推动该技术在核电压力容器上的应用具有重要的指导意义。对电熔增材制造16MND5钢进行了低周疲劳试验研究，试验温度为室温和350℃，采用轴向总应变控制方式，应变比R=-1，应变范围±0.2%～±0.8%。对试验数据进行拟合计算，获得电熔增材制造16MND5钢的应力 应变曲线、应变-寿命曲线和低周疲劳设计曲线等。采用扫描电子显微镜对疲劳试样断口进行了观察，结果显示电熔增材16MND5钢的低周疲劳断口存在多个裂纹源，裂纹扩展区为一系列相互平等的疲劳条带，扩展区同时存在着蠕变孔洞和二次小裂纹，最终断裂区属于韧性断裂。

Low cycle fatigue characteristics of 16MND5 steel produced by electrical additive manufacturing

Electrical additive manufacturing is a new 3D printing technology for heavy metal materials, and 16MND5 steel is a new material produced by the technology. The systematic investigations on the low-cycle fatigue characteristics of the material provide significant guidelines for further applying the technology into the field of nuclear pressure vessels. The low cycle fatigue behaviors of 16MND5 steel are revealed by experiments under temperatures 20℃(room temperature) and 350℃, respectively. In addition, the control method of axially total strain is adopted in the experiment. The strain ratio R is -1 and the strain is within the range (±0.2% to ±0.8%). Furthermore, the stress strain curve, strain life curve and low cycle fatigue design curve of 16MND5 steel are achieved. Finally, the fracture in the specimen is observed by scanning electron microscope. The results show that several crack sources are positioned in the low cycle fatigue fracture of the specimen; the crack growth zone is a series of fatigue bands with same size; creep holes and secondary cracks occurs in the growth zone, and the final fracture zone is a ductile fracture.