As an important precious metal material, pure platinum was used in semiconductor, medical and other fields. The uniformity of grain structure and overall size were very important to the performance of the material. The grain morphology of pure platinum bar prepared by different methods was observed by metallographic microscope and microhardness tester, and the influence of forging, cold working deformation and annealing process on the grain uniformity of platinum bar was studied by quantitative software. The results showed that the recrystallization of pure platinum with 80% deformation was basically completed at 700℃ for 1.5 h. The pure platinum with 40% small deformation was kept at 900℃ for 1.5 h, and the grain size grew up to 155.2 m, with the best overall uniformity. To obtain a pure platinum bar with fine uniform recrystallized grain structure, the cast bar was forged and cold rolled, the cold rolling process deformation amount was 5%~10%, the final deformation amount was 80%, the formed platinum bar was annealed at 700℃ for 1.5 h, the grain size reached 47.8 μm, the hardness was 46.0, which met the requirements of pure platinum bar. |