Mechanisms of Crack Formation in Nickel-Based Superalloys Processed by Selective Laser Melting This article reviews the mechanisms, types, and causes of cracks in nickel-based superalloys fabricated by Selective Laser Melting. Due to low thermal conductivity, wide solidification range, and severe shrinkage, SLMed superalloys are prone to solidification cracking, liquation cracking, DDC, and SAC. These defects arise from interdendritic segregation, liquid-film rupture, grain-boundary sliding, γ′ coarsening, and rafting. Although powder design, optimized scanning strategies, and heat treatment can reduce cracking, challenges remain. Future research must focus on process optimization, new alloy formulations, and improved post-processing to enhance the reliability of SLM-produced nickel-based superalloy components.