High cycle fatigue of ARMCO iron severely deformed by ECAP

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 681; pp. 85 - 96
• Main Authors: Muñoz, Jairo Alberto, Higuera, Oscar Fabián, Cabrera, José María
• Format: Journal Article Publication
• Language: English
• Published: Lausanne Elsevier B.V 10.01.2017; Elsevier BV
• Subjects: Acer; Acer d'alta resistència; Annealing; Cast iron; Crack propagation; Deformation; Dimpling; Electron back scatter diffraction; Electron backscatter diffraction; Enginyeria dels materials; Equal channel angular pressing; Failure analysis; Fatigue failure; Fatigue life; Fatigue limit; Fatigue tests; Fracture surfaces; Grain boundaries; Grain size; High cycle fatigue; High-Cycle Fatigue (HCF); Inverse Polo Figure (IPF); Iron; Microstructure; Orientation Distribution Function (ODF); S-N curve; Striations; Temperature; Texture; Àrees temàtiques de la UPC; High-Cycle Fatigue (HCF); Inverse Polo Figure (IPF); S-N curve; Fatigue limit; Orientation Distribution Function (ODF)
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2016.10.010

The high-cycle fatigue behavior of ARMCO iron severely deformed by Equal Channel Angular Pressing (ECAP) at room temperature through route Bc until 8 passes, with an average grain size of ~365nm, was studied and compared with the same material in the annealed state with an average grain size of ~72µm. The fatigue limit of the 8 passes ECAPed sample increased with respect to the annealed material by more than 250% rising from 274MPa to 717MPa. Striations and dimpled relief were observed on the fracture surfaces of the fatigued ultrafine and coarse grain fatigue samples. The microstructure was characterized by Electron Backscattered Diffraction (EBSD) before and after the fatigue tests and it was observed in both samples an increment in the fraction of Low Angle Grain Boundaries (LAGB) at high number of cycles to failure. A texture analysis for the materials after the fatigue failure was done. This study shown a preferential orientation towards the γ fiber for both conditions.