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Kumar Amit, Pandey Shailesh M., Pandey Chandan

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 1

art. no. e54, 2023

EN

A dissimilar joint of martensitic grade P92 and Ni-based Inconel 617 (IN617) alloy are employed commonly in advanced ultra-supercritical (AUSC) units to fabricate thick section components such as steam pipes and turbine rotors. This study investigated the weldability of the IN617 alloy and P92 steel dissimilar welds. Ni-based superalloy ERNiCrMo-3 filler was used to attempt the dissimilar joining for conventional V groove and narrow groove design by employing the gas tungsten arc welding (GTAW) process. The weld metal for the capping pass, backing pass, and near the interface showed the columnar and cellular grains while equiaxed grains are observed corresponding to root and filling passes. The energy dispersive spectroscopy and Electron probe micro-analyzer (EMPA) study confirmed the segregation of the Nb and Mo particles in inter-dendritic spaces and resulted in the formation of the Nb-rich NbC and laves phases and Mo-rich phases. The EDS line map and EPMA study of the P92 interface showed a sharp increase in Cr, Mo, and Ni concentration and a steep decrease in Fe concentration as moving from P92 base metal to weld metal. A negligible diffusion from filler weld to IN617 or vice versa across the IN617 interface was detected. The microhardness gradient along the weldments indicated a sharp rise in hardness value near the P92 fusion boundary due to the formation of the unmixed zone of lower hardness and the P92 coarse-grained heat-affected zone of higher hardness. The weld metal hardness results showed a great variation with an average hardness value for V groove and narrow groove welds of 227 and 262 HV, respectively. The mechanical tests were conducted at the ambient temperatures and data obtained for the weldments were compared with the base metals. The room temperature tensile tests showed the failure from the region of the P92 BM or the interface of P92 BM/weld metal, with joint strength of 646 ± 6 MPa and 747 ± 4 MPa in AW conditions for V groove and narrow groove, respectively. The Charpy impact test (CIT) also showed the variation in impact toughness along the weldments, and the ERNiCrMo-3 filler weld was identified as the weakest region of the welded joint in terms of impact toughness for both the groove designs. The residual stress variation along the thickness of the weld plate was measured using the deep hole drilling (DHT) methods, and the results indicated the peak magnitude of the residual stress for the V groove welded joint. The test results indicated that welded joint produced using ERNiCrMo-3 filler was safe for AUSC power plants' boiler applications for both the groove weld while optimum mechanical properties were measured for narrow groove weld.

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Effect of Karanja biodiesel blends on the characteristics of diesel engine

Yadav Sandeep, Kumar Amit, Chaudhary Abhilasha

Zeszyty Naukowe. Transport / Politechnika Śląska

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2022

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z. 115

249--264

EN

Extensive research is being conducted to create and use a wide range of alternative fuels to accommodate the world's growing energy needs. The objective of this experimental investigation was to analyze the effects of Karanja biodiesel blends on the performance, combustion, and emission characteristics of a compression ignition (CI) engine vis-a-vis neat diesel. Important physical parameters of Karanja oil were examined experimentally after transesterification and determined to be within acceptable limits. BTE of Karanja biodiesel blends was about 3-8% lower than diesel. For Karanja biodiesel blends, BSFC was about 2-9% higher than diesel but exhaust gas temperature and volumetric efficiency were lower. Emissions characteristics such as nitrogen oxides, hydrocarbons, and carbon monoxide were also analyzed for various tested fuels. Karanja biodiesel blends resulted in lesser CO and HC formation. Nonetheless, NOx emissions were around 10% greater than diesel. Peak cylinder pressure, heat release rate, and maximum rate of pressure rise versus crank angle were among the combustion characteristics parameters considered in this study. Combustion analysis revealed that for Karanja biodiesel blends heat release rate and peak cylinder pressure were lower than for neat diesel. Findings indicate that Karanja biodiesel can be considered a viable diesel engine fuel.

3

Autogenous laser-welded dissimilar joint of ferritic/martensitic P92 steel and Inconel 617 alloy: mechanism, microstructure, and mechanical properties

Kumar Amit, Pandey Chandan

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 1

art. no. e39, 2022

EN

Dissimilar autogenous welding of ferritic/martensitic P92 steel and Inconel 617 alloy was conducted using the laser beam-welding process. The microstructure evolution such as element segregation, grain size, and precipitate morphology was investigated in different areas of the welded joint for as-welded (AW) and post-weld heat treatment (PWHT) condition by using optical microscopy (OM) and Field Emission Scanning Electron Microscopy (FE-SEM). The tensile strength at room temperature, microhardness variation, and Charpy V impact toughness was evaluated for the welded joint to study the effect of laser beam welding on mechanical properties. Finally, the fractured impact-tested specimen was characterized by FE-SEM. Microstructure observation showed the microstructure heterogeneity across the welded joint. A typical martensitic lath structure devoid of carbide precipitates was observed in P92 HAZ, while Inconel 617 HAZ exhibited the fine-equiaxed austenite grains of average size 24 ± 7 µm with Ti-enriched Ti(C, N) and Mo-enriched carbide precipitates. A columnar and cellular structure consisting of the alloying element segregation in the inter-dendritic areas was observed for the weld metal (WM) near the interface, while the interior WM showed the cellular and equiaxed dendrites along with particles of type NBC, TiC, and M23C6. Fairly good strength and ductility were obtained for the welded joint, and it qualified the ultra-supercritical (USC) boiler requirement. The WM was witnessed as the weakest part of the welded joint for impact strength. However, the impact strength of the WM (61 ± 2 J) was measured higher than the ASME standard value (> 41 J) and EN ISO 3580:2017 standard value (> 47 J) in the AW joint. After the PWHT, a drastic reduction in impact strength of WM (48 ± 3 J) was measured, and it was very close to EN ISO 3580:2017 recommended value of 47 J. The HAZ of P92 and Inconel 617 showed good impact strength for both AW and PWHT joints. The austenitic microstructure in WM exhibited the hardness of 150 ± 8 HV0.5, which was lower than the hardness of P92 and Inconel 617 base metal. The hardness in P92 HAZ was estimated higher than other regions of the weldments (WM and Inconel 617 HAZ). PWHT resulted in a drastic reduction in hardness of P92 HAZ, while WM (154 ± 7 HV0.5) and Inconel 617 HAZ showed a minute change in hardness value. The tensile strength of welded joints for the transverse tensile-tested specimen was also measured higher than the base metal, and fracture was observed in weaker parent metal, i.e., P92 steel for both AW and PWHT joint.

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Reliability estimation of a Network Structure using Generalized Trapezoidal Fuzzy Numbers

Kumar Amit, Dhiman Pooja

Journal of KONBiN

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2021

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Vol. 51, iss. 1

225--241

EN

Classical sets are used commonly to consider reliability. Because of the uncertainty in the data (which considered in the present paper) classical sets fail to describe the reliability accurately. Uncertainty leads to fluctuation in the actual situation of the structure. Fuzzy logic method attempts to test system reliability with the benefit of membership function. Within this context, specific problems of reasoning-based approaches are studied, explored and correlated with standard reliability approaches. In this paper Generalized Trapezoidal Fuzzy numbers (GTrFN) are used to assess the structure's fuzzy reliability. The reliability of each event is assigned with different level of satisfaction and some improved operations on the generalized trapezoidal fuzzy numbers (GTrFN) are used to calculate the fuzzy boundaries for the resultant reliability of the final event along with the degree of satisfaction. Also the results are compared to demonstrate the application of the improved operations on Generalized Trapezoidal Fuzzy Numbers (GTrFN). The obtained results converge to more precise interval values as compare to the vague fuzzy number.

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A Review on Impulse RADAR

Kumar Saket, Kumar Amit, Singh Vikrant, Singh Abhishek Kumar

International Journal of Electronics and Telecommunications

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2021

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Vol. 67, No. 4

579--587

EN

RADAR plays a vital role in military applications since its origin in the 2nd world war. Recently it has been used in surface inception, health monitoring, infrastructure health monitoring, etc. In these applications, Ultra-wideband RADAR systems are more popular than traditional RADAR systems. Impulse RADAR is a special kind of ultra-wideband RADAR, which is mostly used for surface penetration, through-wall imaging, antimissile detection, anti-stealth technology, etc. because of its high resolution and low center frequency. Out of all these applications, impulse RADAR has been used intensively as a ground-penetrating RADAR for the detection of land mines, underlying pipelines, buried objects, etc. This report has attempted to provide the steps for designing the impulse ground penetrating RADAR (GPR) as well as provides the value of crucial parameters required in the design process of commercial GPR systems.

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Studies on the Effect of Nitrate Esters on the Properties of Advanced Energetic Propellants

Kumar Amit, Chavan Prakash V, Sadavarte Vaibhav S, Bhowmik Debdas, Mada S.S.N.M. Santosh, Pande Shrikant M.

Central European Journal of Energetic Materials

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2020

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Vol. 17, no. 3

384--407

EN

Propulsion designers all over the world are exploring the possibility of achieving higher performance by enhancing the energy of solid propellants. This can be achieved by replacing non-energetic ingredients with energetic ones or by replacing low density ingredients, particularly binders, with higher density ones, without affecting the processibility and ageing characteristics. The same has been attempted by using nitroglycerine (NG) and butanetriol trinitrate (BTTN) as plasticizers in propellant compositions. In the present study, NG and BTTN have been used in different plasticizer to polymer ratios (Pl/Po) and various parameters of each composition have been theoretically predicted. Three propellant compositions plasticized with NG, BTTN and a 1:1 combination of NG and BTTN, have been processed and analyzed for targeted properties. From the theoretical data, it was observed that there is a negligible increase in density impulse beyond a Pl/Po ratio of 2, apart from the higher density and calorimetric values of the NG-plasticized propellant; these plasticizers have a significant effect on the ballistic and mechanical properties. Another observation was that the elongation of BTTN and NG/BTTN (1:1) plasticized propellants is significantly higher at a low crosshead rate than NG-plasticized propellant, implying that the two former propellants have higher strain capabilities at low temperatures and can be used for missiles having long term low temperature storage requirements. Thermal decomposition studies have been carried out by DSC, and for each composition 5 distinct peaks were observed.

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Reliability analysis of an industrial system under cost-free warranty and system rest policy

Kumar Pardeep, Kumar Amit

Journal of KONBiN

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2019

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Vol. 49, iss. 2

377--395

EN

The aim of this paper is to analyze a system, which consists of two components, working under a cost-free warranty policy. Past literature reflects that till now the focus of researchers is those systems which work without taking rest. But here authors emphasized on an industrial system which takes rest after working for a specific amount of time. This strategy helps the system to run for a long time with less failure. After taking rest, the system starts its working again. During the mathematical modeling of the system various state of the same are critically analyzed. Reliability of the considered system has been obtained for the different combinations of failure and repair rates. Also, the various parameters which affect the system performance have been evaluated.