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High Al and Ti content nickel-based superalloys with excellent performance are limited by cracking defects, and cannot be effectively applied in additive manufacturing (AM), which are referred to as non-weldable superalloys. Laser powder bed fusion (LPBF) was applied to manufacture non-weldable nickel-based superalloys, and the relationship between LPBF process parameters and the formation mechanism of defects was analyzed. Increasing laser power, decreasing scanning speed and hatch distance can effectively eliminate lack of fusion defects by achieving reasonable melt pool and channel overlap. Elements such as Ta, Nb, and Ti tend to enrich in the interdendritic regions, leading to the precipitation of MC carbides that obstruct liquid solidification during the final solidification stage, thereby inducing the formation of solidification cracking. The top of the melt pool exhibits higher cracking susceptibility compared to the bottom, with cracking more likely to initiate at the top. Solidification cracks preferentially form along high-angle grain boundaries with misorientations >40°. Under moderate laser power (220 W), reducing the scanning speed decreases the fraction of such boundaries while retaining a texture, thereby suppressing solidification cracking. In LPBF, a higher laser power input (280 W) more readily entrains oxygen and promotes Al 2 O 3 formation; these oxides remain incoherent with gammaˊ phase and MC carbides, acting as crack-initiation sites and increasing cracking susceptibility.
Bao et al. (Sat,) studied this question.