The Microstructure and Mechanical Properties of Inconel 718 Fine Grain Ring Forging

Abstract

The microstructure and mechanical properties of fine-grained Inconel 718 ring forging were investigated in this paper. The results indicated that the fine-grained ring forgings can be obtained by forging the fine-grained Inconel 718 bars. The grain size can be as fine as ASTM 10 and the precipitated δ phase are spherical. Heat treated at 980°C/1h/water cooling + 620°C /12h/air cooling, the ring forgings possessed very good mechanical properties. The impact toughness can be over 100J. In the fatigue test with the stress ratio -1, when the theoretical stress concentration factor is 1 and 2.7, the maximum stress for 10 7 fatigue cycles is over 620 MPa and 260 MPa, respectively. IntroductionInconel 718 alloy has been used world-wide in aerospace, aircraft, oil, and chemical industries, and also nuclear power plants because of its high strength, excellent ductility, good formability and weldability etc [1][2][3]. To meet the demands of different service conditions, the die forging process has been investigated intensively in the past few years. Besides two conventional forging processes, including forging driven by hydraulic presses or hammers, and some advanced forging processes, such as hot die forging, insulation die forging and isothermal forging, have been developed to manufacture fine grains forgings. The products of these processes have been applied significantly in new power units [4][5][6].

Electrochemical Polishing of Extruded and Laser Powder-Bed-Fused Inconel 718

“…Pores can be reduced by modifying the scanning strategies [27], but it might be more cost effective when hot-isostatic pressing the bulk number of L-PBF parts. Since Laves phases and pores can be eliminated by homogenizing and hotisostatic pressing [6,8,10,28,29], these post processes could be applied before ECP to achieve a better surface finish.…”