Kim Hoyeol, Cong Weilong, Zhang Hong-Chao, Liu Zhichao
Department of Industrial, Manufacturing and Systems Engineering, Texas Tech University, Lubbock, TX 79409, USA.
School of Mechanical Engineering, Dalian University of Technology, Dalian 116023, China.
Materials (Basel). 2017 Mar 25;10(4):341. doi: 10.3390/ma10040341.
As a prospective candidate material for surface coating and repair applications, nickel-based superalloy Inconel 718 (IN718) was deposited on American Iron and Steel Institute (AISI) 4140 alloy steel substrate by laser engineered net shaping (LENS) to investigate the compatibility between two dissimilar materials with a focus on interface bonding and fracture behavior of the hybrid specimens. The results show that the interface between the two dissimilar materials exhibits good metallurgical bonding. Through the tensile test, all the fractures occurred in the as-deposited IN718 section rather than the interface or the substrate, implying that the as-deposited interlayer bond strength is weaker than the interfacial bond strength. From the fractography using scanning electron microscopy (SEM) and energy disperse X-ray spectrometry (EDS), three major factors affecting the tensile fracture failure of the as-deposited part are (i) metallurgical defects such as incompletely melted powder particles, lack-of-fusion porosity, and micropores; (ii) elemental segregation and Laves phase, and (iii) oxide formation. The fracture failure mechanism is a combination of all these factors which are detrimental to the mechanical properties and structural integrity by causing premature fracture failure of the as-deposited IN718.
作为表面涂层和修复应用的潜在候选材料，通过激光工程净成形（LENS）技术将镍基高温合金因科镍718（IN718）沉积在美国钢铁协会（AISI）4140合金钢基体上，以研究两种不同材料之间的相容性，重点关注混合试样的界面结合和断裂行为。结果表明，两种不同材料之间的界面呈现出良好的冶金结合。通过拉伸试验，所有断裂均发生在沉积态的IN718部分，而非界面或基体，这意味着沉积态的中间层结合强度弱于界面结合强度。从使用扫描电子显微镜（SEM）和能量色散X射线光谱仪（EDS）进行的断口分析来看，影响沉积态部分拉伸断裂失效的三个主要因素是：（i）冶金缺陷，如未完全熔化的粉末颗粒、未熔合孔隙和微孔；（ii）元素偏析和拉夫斯相；（iii）氧化物形成。断裂失效机制是所有这些因素的综合作用，这些因素通过导致沉积态IN718过早断裂失效，对力学性能和结构完整性产生不利影响。
