INVESTIGATION OF THE EFFECT OF ANNEALING ON THE MICROSTRUCTURE AND HARDNESS OF THE EP648 ALLOY AFTER DIRECT METAL DEPOSITION

10.25712/ASTU.1811-1416.2023.01.014

Abstract

Samples of Ni-based super alloy EP648 are received by the method of direct metal deposition. Annealing at temperature 1180 °С during 4 hours is provided. Measurements of hardness, optical metallography, X-Ray analysis are carried out. It was found that direct metal deposition of samples from Ni-based super alloy EP648 lead to the formation of a structure with a strong reflection in the region of the interference angle 2θ=51°, which may belong to a solid solution of alloying elements in nickel, as well as to the phase Ni₃Cr₂. Peaks are observed in the region of interference angles 2θ<40°, which may belong to the phase Ni₂Cr, the particles of this phase are hardly distinguishable in the images of optical metallography. Annealing of the samples at indexed mode leads to hardness increasing from от 19±4 HRC to 34±0.3 HRС. The peaks appear in the region of the interference angle 2θ=43° and 75° as a result of annealing, what is likely for the nickel-based solid solution and the phase Ni₃Cr₂. The face-centered cubic structure is revealed, high value of lattice period is saving; presence of the phase Ni₂Cr is found. Position and height of peaks at small interference angles 2θ<40° does not change.