a b s t r a c tLightweight magnesium alloys, such as AZ31, constitute alternative materials of interest for many industrial sectors such as the transport industry. For instance, reducing vehicle weight and thus fuel consumption can actively benefit the global efforts of the current environmental industry policies. To this end, several research groups are focusing their experimental efforts on the development of advanced Mg alloys. However, comparatively little computational work has been oriented towards the simulation of the micromechanisms underlying the deformation of these metals. Among them, the model developed by Staroselsky and Anand [Staroselsky, A., Anand, L., 2003. A constitutive model for HCP materials deforming by slip and twinning: application to magnesium alloy AZ31B. International Journal of Plasticity 19 (10), 1843-1864] successfully captured some of the intrinsic features of deformation in Magnesium alloys. Nevertheless, some deformation micromechanisms, such as cross-hardening between slip and twin systems, have been either simplified or disregarded. In this work, we propose the development of a crystal plasticity continuum model aimed at fully describing the intrinsic deformation mechanisms between slip and twin systems. In order to calibrate and validate the proposed model, an experimental campaign consisting of a set of quasi-static compression tests at room temperature along the rolling and normal directions of a polycrystalline AZ31 rolled sheet, as well as an analysis of the crystallographic texture at different stages of deformation, has been carried out. The model is then exploited by investigating stress and strain fields, texture evolution, and slip and twin activities during deformation. The flexibility of the overall model is ultimately demonstrated by casting light on an experimental controversy on the role of the pyramidal slip hc + ai versus compression twinning in the late stage of polycrystalline deformation, and a failure criterion related to basal slip activity is proposed.
The wear of TiCN coating carbide cutting tools (Sandvik® Grade 1010 and 4220) in different hard-milling machining conditions was monitored, analyzed, and discussed for AISI H13 steel. This material is commonly used in the forge industry in order to optimize the manufacturing process according to a qualimetry/cost compromise criterion. AISI H13 steel generally is used in modern production for high wear-resistant dies and molds. One of the most basic and primary geometric shapes in the manufacture of molds and die cavities is the geometry known as "inclined plane." Experimental investigations were carried out on a "mold model" design with the aim of analyzing and optimizing the principal manufacturing conditions. The tests are dependent on manufacturing factors, particularly their impactin a complex tribological process. Five clearly defined different surfaces of the hardened AISI H13 steel model mold, with appropriate geometries were studied; i) vertical downward; ii) curved downward; iii) horizontal; iv) curved upward; and v) vertical upward.The analysis of cutting tool wear during this process was based on computerized measurements of visually observable wear and power consumption. Morphological investigations of the surface topography for the cutting tool, as well as of the work-piece surfaces, were systematically carried out. Moreover, the interactions with simultaneously measured energy consumption during the process are also explicated in the present study and therefore tentative methods to optimize hard-milling machining are offered.
Robotic-directed energy deposition has attracted the attention of the research community and industry as a process capable of producing large metallic parts. The selection of the manufacturing conditions is a critical step in improving the process efficiency and quality of the produced parts. The present work aims at analyzing the geometry and surface topography of walls built using several conditions and inclination angles, without additional supports except for the substrate. The walls were made of AWS A5.18. ER70S-6 steel using the Wire Arc Additive Manufacturing process. The study used both dimensional and 3D topography measurements to analyze the results. As findings, the travel speed played an important role in the size of the cross-section due to the heat input to the welding zone. Heat accumulation was a critical factor in the size and accuracy of the beads. Moreover, intermediate cooling provided structures with more uniform dimensions, smaller width, and higher layer growth. The inclination of the pieces influenced the width and uniformity of the beads, generating minor imperfections on the downside of the pieces because of gravity.
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