Influence of XHV-adequate atmosphere on surface integrity

In aerospace engineering, high temperature alloys such as titanium are the preferred choice. However, machining of such materials remains a major challenge due to high process forces and process temperatures. Currently, machining is performed almost entirely in the presence of oxygen. This results in a process-inherent oxidation of the metal surface, which leads to higher tool wear during machining. By means of an oxygen-free machining undesirable oxidation reactions will be avoided and thus results in an extension of tool life. In addition, oxygen-free machining in an extreme high vacuum (XHV) adequate environment can influence the resulting workpiece surface and subsurface properties due to change in process forces and chip formation. In the present work, the influence of machining under air and XHV-adequate atmosphere is examined with regard to chip formation, workpiece surface topography and residual stresses. Significant differences can be seen in resulting surface integrity depending on the machining atmosphere

Chip formation in machining hybrid components of SAE1020 and SAE5140

The requirements for massive high-performance components are constantly increasing. In addition to the reduction of component weight, requirements such as smaller design, more functionality and longer lifetime are increasing. By joining different materials in one component, these contradictory requirements can be met. In the process chain of manufacturing hybrid components, machining as the final step has a decisive influence on the application behavior and service life due to the surface and subsurface properties generated. Thereby thermomechanical loads during machining determine the final subsurface properties and the chip formation mechanisms determine the final surface properties of components. However, for the specific adjustment of required surface and subsurface properties, first of all an understanding of the generation of the addressed properties in the material transition zone is necessary. In the current work, the chip formation and the mechanical loads in the transition zone of hybrid components are presented. Within the scope of orthogonal cutting investigations, the influence of process parameters and tool microgeometry on mechanical loads and chip formation is analyzed. Chip forming has a significant influence on the surface properties of the hybrid component. The chip formation depends on the hardness of the machined material. During machining of hybrid components an abrupt change of the chip shape takes place in the material transition zone. The process variables influence the level in the surface topography of hybrid components. © 2020, The Author(s)

Combination of Cladding Processes with Subsequent Hot Forming as a New Approach for the Production of Hybrid Components

A new process chain for the manufacturing of load-adapted hybrid components is presented. The "Tailored Forming” process chain consists of a deposition welding process, hot forming, machining and an optional heat treatment. This paper focuses on the combination of laser hot-wire cladding with subsequent hot forming to produce hybrid components. The applicability is investigated for different material combinations and component geometries, e.g. a shaft with a bearing seat or a bevel gear. Austenitic stainless steel AISI 316L and martensitic valve steel AISI HNV3 are used as cladding materials, mild steel AISI 1022M and case hardening steel AISI 5120 are used as base materials. The resulting component properties after laser hot-wire cladding and hot forming such as hardness, microstructure and residual stress state are presented. In the cladding and the heat-affected zone, the hot forming process causes a transformation from a welding microstructure to a fine-grained forming microstructure. Hot forming significantly affects the residual stress state in the cladding the resulting residual stress state depends on the material combination.Mechanical Engineerin

Influence of abiotic environmental factors on the abundance and distribution of <i style="">Vibrio</i> species in coastal waters of Kerala, India

587-592Quantification of Vibrio spp. and abiotic environmental factors on the proliferation and longevity of V. parahaemolyticus and V. cholerae was studied. Water samples were collected onboard CRV Sagar Purvi from Veli, Neendakara, Kochi, Calicut and Kasaragod along the Kerala coast for hydrological and microbiological parameters. Pearson correlation and regression analysis were done for evaluating the relationship between abiotic environmental factors and abundance of Vibrio spp. Hydrological and microbiological variations are greatly observed at nearshore transect of all stations. Significant correlation was observed between V. cholerae and nutrients and negative correlation with pH, dissolved oxygen and salinity. The population of V. parahaemolyticus showed an inverse correlation with dissolved oxygen. pH, salinity and nutrients and these factors were responsible for the incidence and abundance of Vibrio cholerae and Vibrio parahaemolyticus. The proliferation and survivality of V.parahaemolyticus in marine waters is independent to hydrological variables while that of V.cholerae is determined by certain abiotic factors

<smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="place" downloadurl="http://www.5iantlavalamp.com/"> Occurrence and distribution of some enteric bacteria along the southern coast of Kerala </smarttagtype>

97-103Six major groups of enteric bacteria, viz, Faecal coliforms, E. coli, Shigella spp., Salmonella spp., Vibrio parahaemolyticus and Vibrio cholerae were screened for the present study. The overall percentage occurrence of enteric bacteria in water and sediment was maximum accounted for Vibrio parahaemolyticus (81.7%) and minimum for Salmonella spp. (9.6%) and moderate reported against Vibrio cholerae (60.6%). The distribution of enteric bacteria was more in the water sample than sediment except Vibrio spp. and the highest occurrence was found to be at Cochin transect, which is the most polluted transect due to enteric microbes. Relationship between the stations on the occurrence of enteric bacteria was linear and significant variations was observed (R2=0.899) and the same pattern of linear regression model was also obtained in source wise occurrence (R2=0.777). The present study elucidates that the health status of the Kerala coast may deteriorates and will be detrimental to the coastal community