A quantitative understanding of the role of ultrasonic treatment (UST) process variables on microstructure and mechanical properties is critical for the development of process maps for manufacturing metal matrix composites (MMCs). This article presents a novel mathematical framework to delineate the functional correlations among ultrasonication time, grain refinement, and hardening in SiC nanoparticle‐reinforced Al matrix composites. UST generates microbubbles and deagglomerates SiC to increase heterogeneous nucleation sites synergistically. The increase in volumetric nucleation density due to SiC addition exhibits slow exponential kinetics with varying ultrasonication time. An outstanding grain refinement efficiency of 62.8% is achieved upon ultrasonication for 90 s. The contributions to an increase in the hardness due to grain refinement and SiC dispersion are isolated to develop correlations between ultrasonication time and hardening. Hardening increases exponentially with treatment time due to the reduction of interparticle distance from sonication‐induced SiC dispersion. These fundamental mathematical correlations constitute a significant advancement toward the development of ultrasonic process maps and MMC manufacturing technology.