The modified 9Cr-1Mo (P91) steel belongs to the family of creep strength enhanced ferritic steels which are widely used for many high temperature service applications like the main steam piping, super heaters, reheaters, headers of fossil fuel fired power plants and in fast breeder reactors of nuclear steam generators. The alloy has several desirable properties like higher strength at elevated temperatures, better rupture life at creep temperatures of the order of 600 8C, better resistance to high temperature oxidation and corrosion and good weldability which makes this material the ideal candidate for power generation industries [1,2]. The weld metal of modified 9Cr-1Mo steel consists of very hard martensitic phase in the as-welded condition and has to be subjected to a proper post weld heat treatment (PWHT) for tempering the martensitic structure of the weld metal and to improve the weld ductility by way of reduction of hardness [3]. As per the recommendations of ASME Boiler and Pressure Vessel Code -VIII Division 1 [4], the weld metal of modified 9Cr-1Mo steel has to be subjected to a post weld heat treatment (PWHT) at a soaking temperature in the range of 730-775 8C.In the absence of an adequate PWHT, it is learnt that the martensite phase present in modified 9Cr-1Mo welds would remain in the untempered condition exhibiting high hardness. This untempered martensite is highly deleterious for service performance and is likely to cause premature failures. There
Distortion is a perennial problem faced by engineers engaged in welding fabrication. The shape change deformations and change in the dimensions that occur after welding is termed as distortion, leading to various undesirable consequences. So there exists a necessity to control distortion within limits. When distortion exceeds acceptable limits, correction of distortion after the complete fabrication results in major reworking operation that consumes both fabrication time and cost. Distortion control in complex structures has always been a challenge to fabrication engineers, dealing with stainless steels. To arrive at an appropriate control method, an in-depth analysis of the shape change deformation behavior of the component and adaptation of appropriate methods to control distortion are essential. In this study, two circular components made of stainless steel have been taken up for control of distortion. The first structure is the labyrinth used in hydro turbine assembly that consists of a ring type of flange made of martensitic stainless steel (ASTM grade A240 S41500) welded with a shell type web using grooved fillet welds. The size of the welded assembly is huge and the quantum of weld is very high leading to heavy distortion that often required to be corrected by way of weld build-up and subsequent machining. The second one is the vortex finder assembly which is a part of cyclone separator that is used to separate the fine particles of coal from coarse ones for use in the combustion chamber of typical Circulating Fluidised Bed Combustion (CFBC) boilers. This is again a cylindrical structure with three shells joined with three flanges and supported by stiffeners. The structure is made of special grade Austenitic stainless steel to withstand high temperature. In both the structures, most of joints are of Tee-joints with fillet welds. During fabrication of these assemblies, the angular tilt, local waviness and the diameter variation were the major issues. Correction after fabrication is not viable considering the configuration and shape of the component. This calls for control of distortion during fabrication itself. Towards this, a suitable welding procedure using an appropriate weld sequence was evolved after studying the weld details of the components. This weld sequence was implemented in-situ in actual components. During fabrication on-line monitoring was carried out and course corrections were provided. After implementation of the weld sequence, it was found that the distortion of the component could be reduced and contained well within the permissible limits. This made the extra rework redundant thus leading to a significant reduction in the cycle time of manufacture of the component. The details of the methodology adopted are described in this paper. Keywords: Labyrinth assembly, vortex finder assembly, stainless steel welding, distortion, T joint, grooved fillet weld, angular tilt, weld sequence.
The diagnosis of skin cancer has been identified as a significant medical challenge in the 21st century due to its complexity, cost, and subjective interpretation. Early diagnosis is critical, especially in fatal cases like melanoma, as it affects the likelihood of successful treatment. Therefore, there is a need for automated methods in early diagnosis, especially with a diverse range of image samples with varying diagnoses. An automated system for dermatological disease recognition through image analysis has been proposed and compared to conventional medical personnel-based detection. This project proposes an automated technique for skin cancer classification using images from the International Skin Imaging Collaboration (ISIC) dataset, incorporating deep learning (DL) techniques that have demonstrated significant advancements in artificial intelligence (AI) research. An automated system that recognizes and classifies skin cancer through deep learning techniques could prove useful in the medical field, as it can accurately detect the presence of skin cancer at an early stage. The ISIC dataset, which includes a vast collection of images of various skin conditions, provides an excellent opportunity to develop and validate deep learning algorithms for skin cancer classification. The proposed technique could have a significant impact on the medical industry by reducing the workload of medical personnel while providing accurate and timely diagnoses..
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