Browsing by Author "Pandey C."

Now showing 1 - 20 of 50

Achieving optimized tungsten inert gas butt welding conditions of thin cold rolled steel sheets by response surface methodology and artificial neural networks
(2018) Giri A.; Pandey C.; Mahapatra M.M.
This paper describes the multiresponse optimization of tungsten inert gas welding for an optimal parametric combination to predict the weld characteristics of thin cold rolled steel sheets. The interaction effects of tungsten inert gas welding process parameters such as welding current, arc length, and traverse speed have been observed on the weld characteristic responses such as weld width, heat-affected zone width, and under-bead depression. Full factorial design of experiment was followed for determining the combinations of the experimental runs. Regression analysis was carried out to develop the mathematical models for the welding control factors and responses. Analysis of variance was used to check the adequacy of the developed mathematical model. The confirmatory tests were conducted to validate the accuracy of mathematical model. Sensitivity analysis was also done to analyze the effect of each individual process parameter on the weld responses. The full factorial experimental data was further utilized for multi-response optimization of the tungsten inert gas process parameters. It was observed that weld responses like weld width and heat-affected zone width could be optimized by regression modeling technique while the under-bead depression showed uncertain behavior. The under-bead depression ranged from 0.0 to 0.15 mm and was observed only when the arc traverse speed was at the lowest level (4 cm/min) for all values of the welding current and arc length. The experimental data were also modeled using the artificial neural network technique for the prediction of weld responses and the results were compared with that from the regression analysis. � IMechE 2017.
An assessment for mechanical and microstructure behavior of dissimilar material welded joint between nuclear grade martensitic P91 and austenitic SS304 L steel
(2019) Thakare J.G.; Pandey C.; Mahapatra M.M.; Mulik R.S.
The microstructural evolution and mechanical properties of gas tungsten arc welded creep strength enhanced martensitic (CSEM) and austenitic stainless steel (SS) dissimilar welded joint is explored in the as welded (AW) and post weld heat treated (PWHT) conditions. The as received normalized and tempered P91 steel has been welded with SS304 L by preparing a conventional groove and employing a P91 GTAW filler wire. The welded plate is subjected to PWHT at 760 �C for 120 min followed by air cooling. The P91 steel in as received condition exhibited fully martensitic (tempered) structure with lathe morphology and prior austenite grain boundaries while SS304 L have austenitic structure with twins. The heterogeneity (as-welded condition) across the welded joint were produced in terms of microstructure and mechanical properties (hardness, Charpy toughness and tensile strength). The variation in mechanical properties has been minimized after the PWHT. PWHT has observed a drastic influence on mechanical properties and microstructure of weld fusion zone and HAZ of P91 side however, remain unaffected for the SS304 L side HAZ. The strength of the welded joint have been measured 1016 � 2.5 MPa and 906 � 6.5 in as-welded and PWHT condition with joint efficiency of 140 % and 125 %, respectively. � 2019 The Society of Manufacturing Engineers
Autogenous tungsten inert gas and gas tungsten Arc with filler welding of dissimilar P91 and P92 steels
(2018) Pandey C.; Mahapatra M.M.; Kumar P.; Saini N.
Creep strength ferritic/martensitic modified 9Cr-1Mo-V-Nb (P91) steel also designated as ASTM A335 and P92 steel are used for piping, cladding, ducts, wrappers, and the pressure vessel in Gen IV nuclear reactors. In the present investigation, a comparative study of the effect of autogenous tungsten inert gas welding (A-TIG) with double pass and multipass gas tungsten arc (GTA) welding with filler on microstructure evolution in the weld fusion zone and the mechanical properties of P91 and P92 steel welded joints was carried out. The microstructure evolution was studied in as-welded and postweld heat treatment (PWHT) condition. The study also focused on the evolution of d-ferrite patches and their influence on the tensile properties of welded joints. PWHT was carried out at 760 C with durations from 2 to 6 h. To study the effect of d-ferrite evolution on mechanical properties, Charpy toughness, microhardness, and tensile tests were performed. The acceptable microstructure and mechanical properties were obtained after the 6 h of PWHT for A-TIG arc welding process while for GTA weld with filler wire, it was obtained after the 2 h of PWHT at 760 C. � 2018 by ASME.
A brief study on ?-ferrite evolution in dissimilar P91 and P92 steel weld joint and their effect on mechanical properties
(2018) Pandey C.; Mahapatra M.M.; Kumar P.; Saini N.; Thakre J.G.; Vidyarthy R.S.; Narang H.K.
Ferritic/martensitic 9Cr-1Mo-V-Nb steel also designated as ASTM A335 used in construction of several components of power plants operating in temperature range of 600�650 �C. In present investigation, dissimilar weld joint of P91 and P92 steel were prepared using the autogenous tungsten inert gas (A-TIG) welding and multi-pass gas tungsten arc welding (GTAW) process. A comparative study was performed on evolution of ?-ferrite patches in weld fusion zone and heat affected zones (HAZs) of welded joints. The evolution of ?-ferrite patches was studied in as-welded and post-weld heat treatment (PWHT) condition. PWHT was carried out at 760 �C for tempering time of 2 h and 6 h, for both A-TIG and GTA weld joints. It was observed that presence of higher content of ferrite stabilizer in P92 steel promote the formation of ?-ferrite patches in weld fusion zone as well as HAZs. To study the effect of welding process and PWHT, Charpy V impact energy and microhardness tests were performed. For microstructure characterization, field-emission scanning electron microscope (FESEM) and optical microscope were utilized. � 2017 Politechnika Wroc?awska
Characterisation of dissimilar P91 and P92 steel welds joint
(2019) Pandey C.; Mahapatra M.M.; Kumar P.
In the present study, dissimilar weld joint was prepared using the P91 and P92 steel plate of 8-mm thickness, using the multi-pass gas tungsten arc (GTA) welding with filler (weld 1) and autogenous tungsten inert gas welding (A-TIG) process (weld 2). Evolution of ?-ferrite patches was studied in weld zone and heat affected zone (HAZ) for both weld 1 and weld 2. Effect of varying post weld heat treatment (PWHT) duration was also studied on ?-ferrite patches and mechanical properties of the dissimilar weld joint. PWHT was carried out at 760�C. For weld 2, weld zone showed poor impact toughness and higher peak hardness as compared to weld 1. After the PWHT, a considerable reduction in hardness was obtained for both weld 1 and weld 2,while impact toughness of weld zone showed a continuous increment with PWHT duration. For weldments characterisation, optical microscope, scanning electron microscope (SEM) and microhardness tester were utilised. � 2018, � 2018 Informa UK Limited, trading as Taylor & Francis Group.
Characterization and evaluation of mechanical properties of CSEF P92 steel for varying normalizing temperature
(2017) Saini N.; Pandey C.; Mahapatra M.M.
The microstructural and mechanical properties of creep enhanced ferritic (CSEF) steels are affected by various parameters, solutionizing temperature is one of them. In the present investigation, the effect of normalizing temperature on the microstructural and mechanical properties of cast and forged (C&F) P92 steel were carried out. Grade P92 steel is considered as a candidate material for Thermal and Nuclear power plants at temperatures of up to 650��C. In this study, C&F P92 steel was subjected to various normalizing temperatures (from 950��C to 1150��C). For microscopic characterization, Optical microscope and Field emission scanning electron microscope (SEM) were used. The grain size, precipitate size, area fraction of precipitates and Cr/Fe were calculated from micrographs. The normalized specimens were tested for tensile strength, hardness, and toughness. Considering observation for the optimum combination of strength, ductility, and toughness, the normalizing at 1000��C and tempering at 760��C has been suggested for C&F P92 steel. � 2017 Elsevier B.V.
Characterization of Cast and Forged (C&F) Gr. 91 Steel in Different Heat Treatment Condition
(2017) Pandey C.; Mahapatra M.M.; Kumar P.; Saini N.
The present research work deals with the results of influence of different heat treatment conditions on the microstructure stability and mechanical properties of high-chromium X10CrMoVNNB9-1(P91) cast and forged (C&F) P91 steel. The C&F P91 steel was subjected to various tempering condition in the temperature range of 350�760 �C and tempering time of 2 h, after the normalizing at 1040 �C for 40 min. The steel was also subjected to furnace cooled and water quenched heat treatment. Tempering at 650 and 760 �C produced the fully tempered lath martensitic structure with M23C6, M7C3, M3C and MX precipitates along the prior austenite grain boundaries, lath boundaries and matrix region. Tempering at 350 and 1000 �C produced the partially tempered columnar laths and untempered columnar laths martensite, respectively. The tempering time was also varied from 2 to 8 h for fixed tempering temperature of 760 �C. The optimum microstructure evolution was obtained for 6 h of tempering at 760 �C that led to improved mechanical properties. � 2017 The Indian Institute of Metals - IIM
Characterization of microstructure of HAZs in as-welded and service condition of P91 pipe weldments
(2017) Pandey C.; Giri A.; Mahapatra M.M.; Kumar P.
Steels 9-12% Cr, having the high creep rupture strength are advocated for the modern low polluting thermal power plants. In the present investigation, the P91 pipe weldments have been characterized for microstructural responses in as-welded, post-weld heat treatment (PWHT) and ageing conditions. The PWHT of welded samples were carried out at 760 �C for time of 2 h and ageing at 760 �C for 720 h and 1440 h, respectively. The effect of time has been studied on precipitates size, distribution of precipitates and grain sizes present in various zones of P91 steel weldments. The impact toughness and hardness variation of heat affected zone (HAZ) have also been studied in as-welded condition as well as at different heat treatment condition. A significant change was observed in grain size and precipitates size after each heat treatment condition. The maximum impact toughness of HAZ was obtained after PWHT at 760 �C for 2 h. The main phase observed in weld fusion zone in as-welded, PWHT and ageing conditions were M23C6, MX, M7C3, Fe-rich M3C and M2C. The unwanted Z-phase (NbCrN) was also noticed in weld fusion zone after ageing of 1440 h. � 2017, The Korean Institute of Metals and Materials and Springer Science+Business Media Dordrecht.
Characterization of P92 Steel weldments in as-welded and PWHT conditions: Room-temperature tensile tests and microhardness measurements led to improving the ductility of the weld joints
(2018) Saini N.; Pandey C.; Mahapatra M.M.; Mulik R.S.
P92 steels have been developed as a candidate material for power plant components that operate in a temperature range of 620o-650�C. A heterogeneous microstructure formation across the P92 weldments makes the wettability of P92 steel a serious issue. The other problem that arises in P92 steel weldments is the formation of ?-ferrite due to the presence of a higher weight percentage of ferrite stabilizers such as V and Nb. as well as W and Mo. In the present work, the shielded metal arc welding (SMAW) process was utilized to prepare the P92 steel weld joints. After welding, postweld heat treatment (PWHT) was performed at 760�C for 2 h. To characterize the weld joints, room-temperature tensile tests and microhardness measurements were performed in the as-welded and PWHT conditions. The subsequent PWHT resulted in a decrease in the hardness gradient across the weldments. The PWHT resulted in enhancing the : ductility of the weld joints. � 2018 American Welding Society. All rights reserved.
Characterization of slurry-based mullite coating deposited on P91 steel welds
(2019) Kanwal S.; Thakare J.G.; Pandey C.; Singh I.; Mahapatra M.M.
Ceramic coatings are widely used as thermal and environment barrier coatings due to their inert properties and capability to withstand high temperature. Ceramic coatings are commonly deposited by air plasma spray process and electron beam physical vapor deposition. In the present work, a cost-effective, slurry-based dip coating technique was developed to deposit mullite-based ceramic coating on the P91 steel substrate. The coating has been characterized by X-ray diffraction technique and scanning electron microscopy. Sintering of coatings was carried out in the temperature range of 900�1000��C. Sintering time was varied between 0.5 and 1�h. Energy dispersive spectroscopy was carried out to study the distribution and diffusion of constituent elements during high-temperature sintering. Potentiodynamic polarization tests and thermo-gravimetric analysis were performed to investigate the corrosion behavior of the coating. The coating sintered at 1000��C was found to be free from cracks and other microdefects. The corrosion rate of coating sintered at 1000��C was found to be 26.06�mpy whereas the uncoated sample showed a higher corrosion rate of 153.7�mpy. � 2018, Australian Ceramic Society.
Characterization of weld fusion zone for TIG welded p91 and P92 steels
(2018) Pandey C.; Mohan Mahapatra M.; Kumar P.; Kumar P.; Thakare J.G.
The welding of nuclear grade P91 and P92 steel plate of thickness 5.2 mm were performed using the autogenous tungsten inert gas (TIG) welding process. The welded joint of P91 and P92 steel plate were subjected to the varying post weld heat-treatment (PWHT) including the post weld heat treatment (PWHT) and re-austenitizing based tempering (PWNT). A comparative study was performed related to the microstructure evolution in fusion zone (FZ) of both the welded joint using the scanning electron microscope and optical microscope in a different condition of heat treatment. The hardness test of the FZ for both joints was also conducted in a different condition of heat treatment. P92 steel welded joint have observed the higher tendency of the ? ferrite formation that led to the great variation in hardness of the P92 FZ. The homogeneous microstructure (absence of ? ferrite) and acceptable hardness was observed after the PWNT treatment for both the welded joint. � 2018 Polish Academy of Sciences. All Rights Reserved.
Comparative study of autogenous tungsten inert gas welding and tungsten arc welding with filler wire for dissimilar P91 and P92 steel weld joint
(2018) Pandey C.; Mahapatra M.M.; Kumar P.; Saini N.
Creep strength enhanced ferritic/martensitic 9Cr-1Mo-V-Nb (P91) steel is also designated as ASTM A335 used for out-of-core and in-core (piping, cladding, ducts, wrappers, and pressure vessel) of Gen IV reactors. In present investigation, the dissimilar weld joint of P91 and P92 steel were made using the autogenous tungsten inert gas (TIG) welding with single pass, double side pass and multi-pass gas tungsten arc (GTA) welding with filler wire. Microstructure evolution in sub-zones and mechanical properties of dissimilar welded joints were studied in as-welded and post weld heat treatment (PWHT) condition. Formation of ?-ferrite patches in weld fusion zone and heat affected zones (HAZs) and their influence on the mechanical behaviour of the welded joints were also studied. Presence of higher content of ferrite stabilizer in P92 steel have resulted the formation of ?-ferrite patches in weld fusion zone as well as HAZs. The ?-ferrite was observed in autogenous TIG welds joints. The ?-ferrite patches were formed in as-welded condition and remained in the microstructure after the PWHT. The ?-ferrite patches leads to reduction in Charpy toughness of autogenous TIG welds joint and also lower down the average hardness of weld fusion zone. Peak hardness and poor impact toughness were observed for autogenous TIG welds joint as compared to GTA welds. For microstructure characterization, field-emission scanning electron microscope (FESEM) with energy dispersive spectroscopy (EDS) and optical microscope were utilized. � 2017 Elsevier B.V.
A comparative study of ductile-brittle transition behavior and fractography of P91 and P92 steel
(2017) Saini N.; Pandey C.; Mahapatra M.M.; Narang H.K.; Mulik R.S.; Kumar P.
The modified 9Cr-1Mo (P91) and 9Cr- 0.5Mo- 1.8W (P92) steel used in fast breeder reactor is exposed to irradiation during service which severely affects the dynamic fracture resistance by increasing the ductile to brittle transition temperature (DBTT). Thus, even at room temperature, the steel can become brittle and prone to cracking. In the present investigation, to elucidate the influence of low temperature on the DBTT, Charpy toughness test was performed on creep strength enhanced ferritic P91 and P92 steel. Lower DBTT was observed for the P92 steel as compared to P91 steel. To find the mode of fracture, the fractured Charpy toughness specimens were investigated using a field electron scanning electron microscope (FESEM). The fracture surface revealed the brittle mode of fracture at a lower temperature for both the steels while the mixed mode of fracture was noticed at room temperature and above. � 2017 Elsevier Ltd
A comparative study of transverse shrinkage stresses and residual stresses in P91 welded pipe including plasticity error
(2018) Pandey C.; Mahapatra M.M.; Kumar P.
The paper deals with the measurement of the residual stresses in P91 welded pipe using the blind hole drilling technique. The P91 pipe weld joints were prepared using gas tungsten arc welding process. The residual stress measurement was carried out using the strain gauge rosette that was associated with the plastic deformation of material and stress concentration effect of multi-point cutting tool. Strain gauge response was estimated experimentally using the tensile testing for the uniaxial loading while finite element analysis was performed for biaxial loading. Gas tungsten arc welds joint was prepared for conventional V-groove and narrow groove design. The corrective formulation was developed for calculating the corrected value of residual stresses from the experimentally obtained strain value. The corrected and experimental induced residual stresses values as per ASTM E837-13 were calculated for both V-groove and narrow groove design. Post weld heat treatment (PWHT) of P91 welded pipe was also conducted to study their effect on residual stresses. � 2018 Politechnika Wroc?awska
Corrigendum to �A brief study on ?-ferrite evolution in dissimilar P91 and P92 steel weld joint and their effect on mechanical properties� [Archives of Civil and Mech Engineering 18 (2018)713�722](S1644966517301814)(10.1016/j.acme.2017.12.002)
(2019) Pandey C.; Mahapatra M.M.; Kumar P.; Saini N.; Thakare J.G.; Vidyathy R.S.; Narang H.K.
The authors regret that The authors regret for any inconvenience caused. � 2019 Politechnika Wroc?awska
Dissimilar joining of CFEF steels using autogenous tungsten-inert gas welding and gas tungsten arc welding and their effect on ?-ferrite evolution and mechanical properties
(2018) Pandey C.; Mahapatra M.M.; Kumar P.; Saini N.
Ferritic/martensitic 9Cr-1Mo-V-Nb steel also designated as ASTM A335 used in construction of several components of power plants operating in temperature range of 600�650 �C. In present investigation, dissimilar weld joints of P91 and P92 steel were prepared using the autogenous tungsten inert gas welding (A-TIG) and multi-pass gas tungsten arc (GTA) welding process. A comparative was performed on evolution of ?-ferrite patches in weld fusion zone and heat affected zone (HAZ) of welded joints. The evolution of ?-ferrite patches was carried out in as-welded and post-weld heat treatment (PWHT) condition. PWHT was carried out at 760 �C for 2 h for both A-TIG and GTA welding process. For A-TIG weld joint higher yield strength, ultimate tensile strength (UTS) and peak hardness were measured due to higher heat input in single pass and higher carbon content in weld fusion zone. Higher heat input, fast cooling rate and higher weight percentage of ferrite stabilizer like vanadium (V) and niobium (Nb) in A-TIG weld joint were resulted in formation ferrite patches in weld fusion zone and heat affected zone. Higher weight percentage of V and Nb in A-TIG weld zone was resulted poor impact toughness of A-TIG weld fusion zone than GTA welds in as-welded condition. After the PWHT at 760 �C�2 h, Charpy toughness of A-TIG weld fusion zone (48 J) just meet the minimum required value as required by the EN: 1557:1997 (47 J). � 2017
Effect of cooling medium on microstructure evolution and tensile properties of creep-strength-enhanced ferritic steel
(2018) Pandey C.; Saini N.; Thakre J.G.; Mahapatra M.M.; Kumar P.
In creep-strength-enhanced ferritic steels, hydrogen-induced cold cracking of weldments is a serious issue. In the present research work, the effect of cooling medium on tensile properties and microstructure evolution of P91 steel weldments has been studied. For water-cooling condition, the diffusible hydrogen metal in deposited metal was measured by the mercury method. The microstructure of weldments in different cooling condition was characterized by using the field-emission scanning electron microscope (FE-SEM) and optical microscope. The fractured tensile test samples were characterized using the FE-SEM. The maximum tensile strength was measured to be 624 MPa for air-cooling medium (very low level of diffusible hydrogen). � 2018 Sociedade Portuguesa de Materiais (SPM)
Effect of creep phenomena on room-temperature tensile properties of cast & forged P91 steel
(2017) Pandey C.; Mahapatra M.M.; Kumar P.; Saini N.
In present research work, the as-received cast & forged (C&F) P91 steel was subjected to the creep test at temperature of 620 �C and 650 �C for applied stress of 120 MPa. The room temperature tensile test was conducted after normalizing and tempering (N&T) treatment of the ruptured creep specimen. The standard tensile-test specimen was prepared from the gauge section of creep ruptured specimen. The N&T treatment was performed to restore the microstructure and mechanical properties of virgin P91 steel (N&T P91 steel). The microstructure of creep fractured specimen in ruptured state and N&T condition were characterized by using field-emission scanning electron microscope (FE-SEM) with energy dispersive X-ray spectroscopy (EDS). The fracture surface morphology of crept specimen and the tensile tested specimen was also studied. The effect of prior creep deformation on the mechanical strength was more significant in the sample with longer creep rupture life. � 2017
Effect of diffusible hydrogen content on embrittlement of P92 steel
(2017) Saini N.; Pandey C.; Mahapatra M.M.
In the present investigation, varying electrode conditions (dried and contaminated) have been employed during welding of P92 steel to study the effect of diffusible hydrogen level on hydrogen-assisted cracking (HAC). Shielded metal arc welding process was employed to deposit the metal on a P92 steel plate. To evaluate HAC, the Granjon implant test with varying diffusible hydrogen content in the deposited metal was utilized. The diffusible hydrogen level was measured in the deposited metal by using the mercury method. Lower critical stress (LCS), embrittlement index (EI) and normalized critical stress ratio were evaluated from the Granjon implant test. The fracture surface morphology of fractured implant specimens has been studied by using a field emission secondary electron microscope. The P92 steel plate welded by the contaminated electrode with a high level of diffusible hydrogen was found to be more susceptible to HAC. As diffusible hydrogen content increased in the deposited metal, the LCS value and EI were observed to be decreased. � 2017 Hydrogen Energy Publications LLC
Effect of grit blasting and thermal spraying on microstructure evolution of P91 weldment
(2018) Thakare J.G.; Pandey C.; Mulik R.S.; Mahapatra M.M.; Narang H.K.
In the present work, studies have been carried out on the variations in the microstructure and hardness of P91 base-metal and welded joint. This variations result from the grit blasting and thermal cycle experienced during the thermal spraying process. The microstructural effects have been analyzed in terms of the depth of the deformation zone. Scanning Electron Microscopy and X-ray diffraction were used as characterization techniques. The grit blasting carried out prior to thermal spraying has resulted in the highest change in sub-surface hardness of the heat affected zone (HAZ). However, flame treatment further reduced the subsurface hardness of the heat affected zone. The depth of deformation zone was highest for inter-critical heat affected zone (IC-HAZ). The overall coating process resulted in an increase in subsurface hardness of various regions of HAZ and fusion zone (FZ). The base metal showed a 7% increase in subsurface hardness due to the overall coating process. The IC-HAZ showed maximum variation with 36% increase in subsurface hardness. The coarse grained heat affected zone (CG-HAZ) and FZ did not show any change in subsurface hardness. As a whole, the hardness and microstructure of the welded joint was observed to be more sensitive to the thermal spray coating process as compared to the base metal. � 2018 Polish Academy of Sciences. All Rights Reserved.