EBSD Study of Delta-Processed Ni-Based Superalloy

Abstract

Nickel-based superalloys are extensively used in the aerospace and power generation industries due to their excellent mechanical properties at elevated temperatures and good corrosion resistance. Typically, these alloys require accomplishing critical standards during their manufacturing process. In this study, an Inconel 718 (IN718) Ni-based superalloy was subjected to a delta-processing treatment (DP718) and subsequently deformed at high temperature. Samples were compressed below and above the δ-solvus temperature at two different strain rates of 0.001 s−1 and 0.01 s−1. A detailed microstructural characterization was carried out by the electron backscattered diffraction technique (EBSD). Kikuchi patterns and the orientation relationship of the δ-phase were identified. For samples deformed above the δ-solvus at 0.01 s−1, an increase in the percentage of low angle grain boundaries (LAGB) within deformed grains and a decrease in high angle grain boundaries (HAGB) were observed. Comprehensive observation of the microstructural evolution of IN718 subjected to DP718 using orientation map images was also performed.

Analysis of strain-induced precipitates by delta-processing in Inconel 718 superalloy

“…The intentional δ-phase precipitation cycle, in preparation for subsequent DP718 thermomechanical processing, may control excessive grain growth during hot deformation and may produce a uniform microstructure with ASTM grain sizes primarily ranging from 6 (45μm), 5 (63μm), 4 (90μm) as can be seen in previous reports [10,27,28]. Figure 3 shows the metallographic OM images after double impact hot deformation steps for 50, 500, 5000 s of interpass times between the first and the second deformation steps at a strain rate of 0.1 s -1 of the samples tested at 900, 925, 950, 975 and 1000 °C.…”

Grain Boundary Wetting by the Second Solid Phase: 20 Years of History

“…GB wetting by the second solid phase can have a strong influence on the properties of materials, including Al alloys [18,20,22,23,[25][26][27][28][29][30][31][32][33][34][35], Fe-based alloys and steels [36,, Co-and Ni-based alloys [78][79][80][81][82][83][84][85], Cu alloys [86,88,90], Ti-and Zr-based alloys [91,93,95,97,, Mg alloys [124,126,[128][129][130][131], as well multicomponent and high-entropy alloys [132,134,[136][137][138][139][140][141][142][143][144].…”

“…The decreased cleavage size, in turn, increased ductility [80]. The high-temperature oxidation behavior induced by precipitation in a Ni-Y-Al alloy is also controlled by the wetting of interfaces [82] [79], in a Ni-Y-Al alloy after high-temperature oxidation [82], in the (Ti 45 Ni 55 ) 100−x Fe x (x = 0.5, 1, 3, 5 at%) alloy containing X-phase precipitates and having high hardness and high compressive strength [85], the Invar/Cu bimetal composites [88], NiTi superelastic alloy manufactured by selective laser melting [115], Cu based Ti 2 AlC composite [91] as well as in Bi-containing brass (Cu-3wt%Bi-30wt%Zn) [90]. The transition between discontinuous and continuous precipitation of the Cr-rich phase was observed by the annealing of solution-treated binary Ni-Cr alloys with 30%, 35%, 40%, 45%, and 50% Cr, and ternary ones doped by 0.5% third elements (Cu, Zr, Nb, Fe, and B) [81].…”

“…Almost 20 years have passed since the discovery of the phenomenon of GB wetting by other solid phases in 2004 [17]. The indications of GB wetting by other solid phases were found and studied in a large circle of systems such as Al alloys [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35], Fe-based alloys and steels , Co-and Ni-based alloys [77][78][79][80][81][82][83][84][85], Cu alloys [86][87][88][89][90], Ti-and Zr-based alloys , Mg alloys [124][125][126][127][128][129][130][131], as well multicomponent and high-entropy alloys [132][133][134][135][136]…”

Advances in Microstructural Characterization of Metals by EBSD

“…Mayo et al [2] shown a combination of interrupted tensile tests with crystallographic characterization performed by means of EBSD, by analyzing the evolution of an intercritically deformed micro-alloyed steel. Kanetas et al [3] performed a detailed microstructural characterization by the EBSD of Inconel 718 (IN718) Ni-based superalloy that was subjected to a delta-processing treatment (DP718) and, subsequently, deformed at high temperature. Gondo et al [4] studied the evolution of texture in the thickness direction of the cylindrical cup, which was spun from a rolled aluminum sheet in 13 passes, using electron backscatter diffraction pattern analysis.…”