Mejora de la resistencia al desgaste abrasivo de un revestimiento Fe-Cr-Mn-C mediante la adición de V

El presente trabajo persigue incrementar la resistencia al desgaste abrasivo de un revestimiento, aplicado sobreplacas de acero al carbono del tipo AISI 1020, utilizando electrodos tubulares revestidos con el sistemade aleación Fe-Cr-Mn-C. Con la finalidad de lograr este incremento, al sistema de aleación se le adicionó V.Los depósitos resultantes se estudiaron mediante microscopía óptica (MO), difracción de rayos-X y ensayosde microdureza. Los ensayos de resistencia al desgaste por abrasión se llevaron a cabo en acuerdo con el procedimientola norma ASTM G 65-B. Los resultados mostraron que la adición de V al sistema Fe-Cr-Mn-Coriginó modificaciones microestructurales significativas, disminuyendo la cantidad de martensita en el depósito,y aumentando el tamaño de la zona eutéctica. Asimismo, el V originó la formación de VC, además delos carburos Cr7C3 presentes para los dos sistemas de aleación. Estas modificaciones microestructurales causaronque los depósitos que utilizan el sistema de aleación Fe-Cr-Mn-V-C presenten una resistencia al desgasteabrasivo significativamente mayor.Palabras clave: Revestimiento, Soldadura, Desgaste, Abrasión, Vanadio, Microestructura

Formability of the 5754-aluminum alloy deformed by a modified repetitive corrugation and straightening process

Sheets of 5754-aluminum alloy processed by a modified repetitive corrugation and straightening (RCS) process were tested in order to measure their formability. For this purpose, forming limit curves were derived. They showed that the material forming capacity decreased after being processed by RCS. However, they kept good formability in the initial stages of the RCS process. The formability study was complemented with microstructural analysis (derivation of texture) and mechanical tests to obtain the strain-rate sensitivity. The texture analysis was done by employing X-ray diffraction, obtaining pole figures, and the orientation distribution function. It was noticed that the initial texture was conserved after successive RCS passes, but the intensity dropped. RCS process did not induce ß-fiber, contrary to common deformation process. The strain-rate sensitivity coefficient was measured through tensile tests at different temperatures and strain rates; the coefficient of the samples processed after one and two passes were still relatively high, indicating the capacity to delay necking, in agreement with the good formability observed in the initial passes of the RCS processPeer ReviewedPostprint (published version

Microstructure and texture evolution of the Al-20sn alloy processed by equal-channel angular pressing using route C

In this work, the microstructure and texture evolution of an Al-20Sn (mass%) alloy processed by Equal Channel Angular Pressing is presented. The evolution of dislocation cells into subgrains and the mechanical response of the deformed alloy have been emphasized. Samples were characterized by transmission electron microscopy, X-ray diffraction (for microstrain and texture measurements) and Vickers microhardness. It was found, that Al grains, suffered the highest degree of deformation during the ECAP process, however, the evidence showed that the deformation was largely heterogeneous, in terms of crystalline domain and feasibly in misorientation angles. The initial copper texture changes throughout the ECAP process forming an incipient shear texture component (111)[11-2]. The heterogeneity of the results obtained from the Vickers microhardness mapping could be associated to the microstructure resulted after the ECAP process. © 2014 The Japan Institute of Metals and Materials

Production of al foams using the SDP method: Processing parameters and introduction of a new sintering device

The processing of aluminum (Al) foams with maximum porosity of around 70 %, regular pore size and interconnected pores were successfully produced by means of the powder metallurgy method of Sintering Dissolution Process (SDP). The metal powder used for the present study was Al powder with 99.5 % of purity and diameters between 75 μ m and 200 μ m. The chosen Space Holder Particles (SHP) were spherical carbamide CH4N2O particles with diameters ranging from 1 to 2 mm. The optimum sinterization temperature was found at 620 °C, at this temperature, a number of necks between Al particles surfaces were observed; indicating a good cohesion between Al particles, while keeping the porous structure of the green compact. The level of porosity was dependent of the carbamide content and the voids formed within the Al particles after the sinterization process. The sample with 60 wt.% of carbamide showed the lowest yield stress value than those for the samples with 40 and 50 wt.%. The strain values significantly increased when the carbamide content increased from 40 to 60 wt.%. Finally, the results obtained from a new sintering device for producing metallic foams at temperatures below 900 °C are also discussed

Texture and Lattice Distortion Study of an Al-6061-T6 Alloy Produced by ECAP

Equal channel angular pressing (ECAP) is a severe plastic deformation (SPD) technique that produces nanostructured materials. Based on a remarkable grain size reduction, this process has led to improve mechanical properties, such as yield strength, fatigue, UTS, etc. In this work the characterization of the microstructure of the aluminum 6061-T6 alloy; plastically deformed up to ε ≈ 6, by the ECAP process, following route Bc, is presented. For this purpose, the ECAP processed samples were characterized by means of X-ray diffraction (for texture and line profile analysis) and transmission electron microscopy. The initial crystallographic texture vanished after one ECAP pass and a new, well defined, shear texture Cθ was generated. For the subsequent ECAP passes, more shear components: A1θ *, Bθ and \bar{B}θ were also developed. From the orientation distribution function analysis, a shift (generally less than 15°) between some experimental maxima and the reported ideal shear texture positions was observed. From these results, it was found that the microstructure generated with this process was stabilized after the 5th ECAP pass. Finally, the micro-strain analyses, in addition to the texture and transmission electron microscopy, contributed to the understanding of the effect of the physical and mechanical processes that were activated during the SPD-ECAP technique