Ma Liyong, Zhang Ziyong, Meng Bao, Wan Min
School of Mechanical Engineering and Automation, Beihang University, Beijing 100091, China.
School of Mechanical Engineering, Hebei University of Architecture, Zhangjiakou 075000, China.
Materials (Basel). 2021 May 13;14(10):2546. doi: 10.3390/ma14102546.
Electric field-assisted sintering has ubiquitous merits over conventional sintering technology for the fabrication of difficult-to-deform materials. To investigate the effect of sintering pressure and temperature on the densification of Inconel 718 superalloy, a numerical simulation model was established based on the Fleck-Kuhn-McMeeking (FKM) and Gurson-Tvergaard-Needleman (GTN) models, which covers a wide range of porosity. At a sintering pressure below 50 MPa or a sintering temperature below 950 °C, the average porosity of the sintered superalloy is over 0.17 with low densification. Under a pressure above 110 MPa and a temperature above 1250 °C, the sintered superalloy quickly completes densification and enters the plastic yield stage, making it difficult to control the sintering process. When the pressure is above 70 MPa while the temperature exceeds 1150 °C, the average porosity is 0.11, with little fall when the pressure or temperature rises. The experimental results indicated that the relative density of the sintered superalloy under 70 MPa and 1150 °C is 94.46%, and the proportion of the grain size below 10 μm is 73%. In addition, the yield strength of the sintered sample is 512 MPa, the compressive strength comes to 1260 MPa when the strain is over 0.8, and the microhardness is 395 Hv, demonstrating a better mechanical property than the conventional superalloy.
与传统烧结技术相比，电场辅助烧结在制备难变形材料方面具有诸多优点。为了研究烧结压力和温度对Inconel 718高温合金致密化的影响，基于Fleck-Kuhn-McMeeking（FKM）模型和Gurson-Tvergaard-Needleman（GTN）模型建立了一个数值模拟模型，该模型涵盖了广泛的孔隙率范围。在烧结压力低于50MPa或烧结温度低于950℃时，烧结高温合金的平均孔隙率超过0.17，致密化程度较低。在压力高于110MPa且温度高于1250℃时，烧结高温合金迅速完成致密化并进入塑性屈服阶段，使得烧结过程难以控制。当压力高于70MPa且温度超过1150℃时，平均孔隙率为0.11，压力或温度升高时孔隙率下降很小。实验结果表明，在70MPa和1150℃条件下烧结的高温合金的相对密度为94.46%，晶粒尺寸小于10μm的比例为73%。此外，烧结样品的屈服强度为512MPa，应变超过0.8时抗压强度达到1260MPa，显微硬度为395Hv，表明其力学性能优于传统高温合金。
