Long Ping, Wen Dongxu, Min Jie, Zheng Zhizhen, Li Jianjun, Liu Yanxing
State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
College of Mechanical Engineering, Dongguan University of Technology, Dongguan 523808, China.
Materials (Basel). 2021 Mar 29;14(7):1681. doi: 10.3390/ma14071681.
Two single track multi-layer walls with linear energy inputs (LEIs) of 219 and 590 J/mm were deposited by cold metal transfer-based wire arc additive manufacturing system. Combined with the X-ray diffraction technique, scanning electron microscope and uniaxial tensile tests, the influences of LEI and cooling rate (CR) on the microstructure evolution, mechanical properties and fracture mechanisms of the studied steel are analyzed. It is observed that the microstructures of the studied steel are mainly composed of δ-ferrite and austenite dendrites. σ phase is formed on the δferrite-austenite interface under low CR. Meanwhile, the primary dendrites' spacing decreases with the decrease in LEI or the increase in CR, and the maximal primary dendrites' spacing is 32 μm. The values of elongation to fracture roughly decline with the decrease in LEI or the increase in CR, but the variations of ultimate tensile strength and yield stress show an opposite trend. In addition, the mesoscopic damages in the studied steel under low LEI are mainly caused by the coalescence of pores. While under high LEI, the cracks are induced by the dislocations piling up around δ-ferrite.
通过基于冷金属过渡的电弧增材制造系统沉积了两个具有219和590 J/mm线能量输入（LEI）的单道多层壁。结合X射线衍射技术、扫描电子显微镜和单轴拉伸试验，分析了线能量输入和冷却速率（CR）对所研究钢的微观结构演变、力学性能和断裂机制的影响。观察到所研究钢的微观结构主要由δ-铁素体和奥氏体枝晶组成。在低冷却速率下，δ-铁素体-奥氏体界面上形成σ相。同时，随着线能量输入的降低或冷却速率的增加，初生枝晶间距减小，最大初生枝晶间距为32μm。断裂伸长率值大致随着线能量输入的降低或冷却速率的增加而下降，但极限抗拉强度和屈服应力的变化呈现相反趋势。此外，低线能量输入下所研究钢中的细观损伤主要由孔隙合并引起。而在高线能量输入下，裂纹由δ-铁素体周围的位错堆积诱导产生。
