ROLLING OF 316L STAINLESS STELL WITH ROUGH ROLLS: A POSSIBLE TECHNIQUE TO OBTAIN SUPERFICIAL NANOGRAINS

• DOI: 10.37572/EdArt_3006213611

• Palavras-chave: Surface; nanograins; rolling; rough rolls; annealing

• Keywords: Surface; nanograins; rolling; rough rolls; annealing

• Abstract:

  316L stainless steel plates of 5 mm thickness, normalized at 900°C, were cold rolled with different reductions and number of passes by using rolls with three different surface roughnesses: grain heights of  0.17 and 0.33 mm and rombhoid-shaped grains of 1.5 mm height. Subsequently, the rolled samples were annealed at 275°C for 1 h in an effort to achieve superficial nanograins. The plates laminated by using low-roughness rolls had continuous superficial microcrystallization when they were rolled for at least 26 passes. For samples made with rougher rolls, the recrystallized superficial grains formed on the surface (sized ~10–15 μm) were smaller than those below the surface; this behavior was caused by the major deformation induced by repeated indentations. The superficial recrystallization of the sample also tended to be more continuous for higher number of passes; micrographs of the penetration profiles of indentation in the samples rolled with high roughness rolls revealed that a sample rolled 24 times had not yet reached the steady surface topology. As a conclusion, in order to successfully form superficial nanograins, very low roughness rolls must be used as well as a small absolute reduction per pass, followed by annealing. These rolling conditions generate a continuous field of highly superficial deformations, which act as nucleation centers for nanograins during annealing. 

• Número de páginas: 10