Cold spray (CS), a solid-state depositing technique, has recently demonstrated promising application in additive manufacture (AM). Compared with fusion based AM technique, cold spray can eliminate solidification defects and is appropriate to fabricate some materials that are difficult for high energy beam methods, such as Aluminium. In the cold spray process, extreme plastic deformation will occur, which triggers the severe dynamic recrystallization and result in the formation of ultrafine grain structure. For a dense CSed component, the grain structure highly influences its performance. Especially for the grain structure in the region around the impact interface, which decides the bonding of particles. However, due to the extreme processing condition of CS and complicated deformation history around the interface, it is challenging to carryout systematic study on the factors that influence the finial grain structure and make a prediction on the final grain size in this region. Here, a Monte Carlo model was built to simulate the dynamic recrystallization in the Aluminium cold spray process. The influence of impact velocity and single/multiparticle impact on the final grain structure in the interface was investigated comprehensively and independently. And the average grain size on the impact interface predicted by the modelling agreed well with reported experimental results.

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