Effect of laser heating on microstructure and deposition properties of cold sprayed SS304L

• Published in: Materialia 2022-05, Vol.22, p.101372, Article 101372
• Main Authors: Roper, Christopher M., Heczel, Anita, Bhattiprolu, Venkata Satish, Kolonits, Tamás, Gubicza, Jenő, Brewer, Luke N.
• Format: Article
• Language: English
• Subjects: Austenitic stainless steels; Dislocation density; X-ray diffraction (XRD), Cold spray, EBSD
• ISSN: 2589-1529; 2589-1529
• DOI: 10.1016/j.mtla.2022.101372

This paper investigates the effects of laser heated cold spray on the microstructure and mechanical properties of cold sprayed 304L stainless steel (SS304L). In this study, three samples were made by depositing SS304L powder onto SS304L substrates using cold spray (CS) with a nitrogen carrier gas. A laser was used to heat the surface of two of the deposits after cold spray to 750 ℃ and 950 ℃, and the resulting microstructure and mechanical properties were studied. Electron backscatter diffraction (EBSD) and X-ray line profile analysis (XLPA) were used to determine the microstructure and dislocation density in the three depositions both near the surface of the deposition and near the interface of the deposition with the substrate. Vickers microhardness was used to measure the hardness of the material as a function of depth in the samples. It was found that laser heating caused recrystallization in the material and ultimately grain growth, which correlated with a significant decrease in dislocation density in the material and a reduction in hardness for the laser heated deposits. The measured hardness of the material was found to be strongly related to the inverse square root of the grain size as measured by EBSD when accounting for ultrafine grains at the prior-particle interfaces. This paper points to the ability of laser surface heating for effective microstructural manipulation of cold sprayed materials. [Display omitted]