Yao Jun, Xin Bo, Gong Yadong, Cheng Guang
Department of Mechanical Engineering and Automation, Northeastern University, Shenyang 110819, China.
Materials (Basel). 2021 Jun 28;14(13):3609. doi: 10.3390/ma14133609.
Stelite-6/Inconel 718 functionally gradient materials (FGM) is a heat-resisting functional gradient material with excellent strength performance under ultra-high temperatures (650-1100 °C) and, thus, has potential application in aeronautic and aerospace engineering such as engine turbine blade. To investigate the effect of initial temperature on the microstructure and properties of laser metal deposition (LMD) functional gradient material (FGM), this paper uses the LMD technique to form Stelite-6/Inconel 718 FGM at two different initial temperatures: room temperature and preheating (300 °C). Analysis of the internal residual stress distribution, elemental distribution, microstructure, tensile properties, and microhardness of 100% Stelite-6 to 100% Inconel 718 FGM formed at different initial temperatures in a 10% gradient. The experimental results prove that the high initial temperature effectively improves the uneven distribution of internal residual stresses. Preheating slows down the solidification time of the melt pool and facilitates the escape of gases and the homogeneous diffusion of elements in the melt pool. In addition, preheating reduces the bonding area between the gradient layers, enhancing the metallurgical bonding properties between the layers and improving the tensile properties. Compared with Stellite-6/Inconel 718 FGM formed at room temperature, the mean yield strength, mean tensile strength, and mean elongation of Stellite-6/Inconel 718 FGM formed at 300 °C are increased by 65.1 Mpa, 97 MPa, and 5.2%. However, the high initial temperature will affect the hardness of the material. The average hardness of Stellite-6/Inconel 718 FGM formed at 300 °C is 26.9 HV (Vickers hardness) lower than that of Stellite-6/Inconel 718 FGM formed at 20 °C.
司太立合金6/因科镍合金718功能梯度材料（FGM）是一种耐热功能梯度材料，在超高温（650 - 1100°C）下具有优异的强度性能，因此在航空航天工程如发动机涡轮叶片方面具有潜在应用。为研究初始温度对激光金属沉积（LMD）功能梯度材料（FGM）微观结构和性能的影响，本文采用LMD技术在两种不同初始温度下形成司太立合金6/因科镍合金718 FGM：室温以及预热（300°C）。分析了在10%梯度下不同初始温度形成的从100%司太立合金6到100%因科镍合金718 FGM的内部残余应力分布、元素分布、微观结构、拉伸性能和显微硬度。实验结果证明，高初始温度有效改善了内部残余应力的不均匀分布。预热减缓了熔池的凝固时间，有利于气体逸出以及元素在熔池中的均匀扩散。此外，预热减小了梯度层之间的结合面积，增强了层间的冶金结合性能并改善了拉伸性能。与室温下形成的司太立合金6/因科镍合金718 FGM相比，300°C下形成的司太立合金6/因科镍合金718 FGM的平均屈服强度、平均抗拉强度和平均伸长率分别提高了65.1 Mpa、97 MPa和5.2%。然而，高初始温度会影响材料的硬度。300°C下形成的司太立合金6/因科镍合金718 FGM的平均硬度比20°C下形成的司太立合金6/因科镍合金718 FGM低26.9 HV（维氏硬度）。
