1. Nataliia Kovtun 832-AMS Materials Science Department “USE OF STEELS WITH ACICULAR FERRITE STRUCTURE PURPOSED TO INCREASE POWER EFFICIENCY OF FREIGHT RAIL TRAFFIC” Scientific supervisor: Ph.D. O.Uzlov Language supervisor: H. Syrtsova 1 PSACEA

2. Brand New Materials: high properties; affordable cost. 2 Energetics and Transport : weight loss

3. Acicular Ferrite in Steels large austenite grain size; the laths grow in different directions; one particle - a nucleation place for several laths. 3 Fig.1 The formation of the acicular ferrite structure [8]. [8]: S.S. Babu, H.K.D.H. Bhadeshia Mechanism of the Transition form Bainite to Acicular Ferrite; Materials Transactions

4. The high degree of laths misorientation The active opposition to the main crack 4 Fig 3: Distribution of misorientation angles in steel [11]: (a) packet bainite (b) acicular ferrite Fig 2: The main crack in the acicular ferrite structured steel [6] [6]: Ming-Chun Zhao, Ke Yang, Yiying Shan The effects of thermo-mechanical control process on microstructures and mechanical properties of a commercial pipeline steel [11]: J.S. Byun, J.H. Shim, J.Y. Suh et. al. Inoculated acicular ferrite microstructure and mechanical properties

5. Two constructional steels have been investigated (0,21%C and 0,37%C) [7] : “acicular ferrite + TiN” Titanium nitrides do not operate as crack nucleation centers 5 [7]: A. Echeveria, J.M. Rodriguez-Ibabe The Role of Grain Size in Brittle Particle Induced Fracture of Steels

6. Type of steel StructureYTS, MPa К IC, MPa/m² Ti-VAcicular ferrite 560-666133-155 Ti-VF+PF+P590-650134-139 TiAcicular ferrite 519169-176 TiF+PF+P440162-169 6 Acicular ferrite: the yield limit increases; ductile characteristics slightly increase Mechanical properties of steel with different structural states [10] [10]: M.A. Linaza, J.L. Romero, J.M. Rodriguez-Ibabe et. al. Scripta Metallurgica and Materialia 29

7. Conclusions high strength and high impact toughness; a possibility to abandon the expensive alloying elements (V, Nb, Ni, Mo, etc.); work at low operating temperatures (low to -60°C); work under conditions of considerable dynamic loads; reducing the weight of freight cars; 7

8. Thank You for your attention! 8