18 research outputs found

    Control of UFG microstructure in welded carbon steel tubes by cold drawing and annealing

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    The present study is made to develop ultra fine grained microstructure in welded steel tubes, through multiple cold drawing passes followed by an annealing treatment. The average ferrite grain size is reduced from 16 to 1.9 μm. SAE 1019M steel grade used for a typical automotive driveline component is studied. Strains between 0.3 and 1.4 followed by annealing at 400, 450 and 500° C are considered to optimize the combination of cold drawing strain and temperature required to produce ultra fine grained microstructure in steel tubes. At a strain value of 1.4 and annealing temperature, 500°C, polygonal ferrite grains and fine carbide particles are obtained. This microstructure is found to be suitable owing to its combination of high strength and good ductility in steel tubes. Tensile strength as high as 1,061 MPa and 9% elongation is obtained due to microstructural refinement. The strength is increased by 350 MPa compared to the strength of conventional cold-drawn welded tubes

    EMOTION AND SARCASM IDENTIFICATION OF POSTS FROM FACEBOOK DATA USING A HYBRID APPROACH

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    Facebook has become the most important source of news and people’s feedback and opinion about almost every daily topic. Facebook represents one of the largest and most dynamic datasets of user generated content. Facebook posts can express opinions on different topics. With this massive amount of information in Facebook, there has to be an automatic tool that can categorize these information based on emotions. The proposed system is to develop a prototype that help to come to an inference about the emotions of the posts namely anger, surprise, happy, fear, sorrow, trust, anticipation and disgust with three sentic levels in each. This helps in better understanding of the posts when compared to the approaches which senses the polarity of the posts and gives just their sentiments i.e., positive, negative or neutral. The posts handling these emotions might be sarcastic too. When detecting sarcasm in social media posts, the various features that are especially inherent to Facebook must be considered with importance

    Influence of counterbody material on fretting wear behaviour of surface mechanical attrition treated Ti-6Al-4V

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    Surface mechanical attrition treatment (SMAT) was carried out on Ti-6Al-4V. Fretting wear tests were conducted using two counterbody materials (alumina and steel). SMAT resulted in surface nanocrystallization. Due to high hardness, low tangential force coeffl{ligature}cient (TFC) and more TiO 2 layer, fretting wear resistance of SMAT treated samples was higher than that of the untreated samples. TFC values obtained with alumina counterbody were higher than those obtained with steel counterbody. The fretting wear resistance of untreated and treated samples fretted against alumina was lower than that of the samples fretted against steel due to tribochemical reactions at the contact zone. © 2012 Elsevier Ltd

    Fretting wear behaviour of surface mechanical attrition treated alloy 718

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    Alloy 718 was subjected to surface mechanical attrition treatment (SMAT) using SAE 52100 steel balls of a 5 mm diameter for four different treatment durations (15, 30, 45 and 60 min). Fretting wear tests were conducted at different normal loads on untreated and treated samples for 25,000 cycles using alumina as a counterbody material. Microstructural features of the surface layer of samples treated by SMAT were characterized by cross-sectional optical microscopy and transmission electron microscopy. Hardness, surface roughness and residual stress were determined using a nano-indenter, surface roughness tester and X-ray residual stress analyzer respectively. SMAT resulted in the formation of nanocrystallites on the surface and near surface regions, increased hardness, increased surface roughness and compressive residual stress at the surface. Treated samples exhibited lower tangential force coefficient (TFC) compared to untreated samples. Samples treated for 60 min exhibited higher grain refinement, higher hardness, lower surface roughness and higher TFC compared to the samples treated for 30 min. The wear volume and wear rate of samples treated for 30 min were lower compared to those of the untreated samples, which may be attributed to an optimum combination of hardness and toughness and a low work hardening rate of the nanocrystalline structure at the surface of the treated samples. In contrast, the wear volume and wear rate of the samples treated for 60 min were higher than those of untreated samples, presumably due to the higher hardness and reduced toughness of the samples treated for 60 min

    Filament activity in a quiet region flare

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