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1
Content available remote Finite element investigation of IGSCC-prone zone in AISI 304L multipass groove welds
Taraphdar P. K., Pandey C., Mahapatra M. M.
Archives of Civil and Mechanical Engineering
|
2020
|
Vol. 20, no. 2
353--365
EN
AISI 304L stainless steel is most commonly used for spent nuclear fuel management; however, the welded joints of this steel are susceptible to intergranular stress corrosion cracking (IGSCC) under the influence of low-temperature sensitization. In the present research, the temperature history of two different groove designs (conventional and narrow groove) has been analyzed to ascertain the propensity of the weld zone to intergranular corrosion (IGC). 3D finite element models (FEMs) have been developed to retrieve the nodal thermal history and predict the region susceptible to IGSCC. The FEM results predicted a lower duration of exposure to the IGC temperature range for narrow groove design as compared to conventional design. The lower duration of exposure exhibits a lower propensity to chromium carbide precipitation and the tendency to IGSCC. The FEM analysis also has been used to observe the difference in the size of the region susceptible to IGSCC in the heat-affected zone of the respective weld designs. The predicted results obtained from the numerical analysis were validated by comparing the chromium carbide precipitation for both the groove designs.
2
Content available Effect of Grit Blasting and Thermal Spraying on Microstructure Evolution of P91 Weldment
Thakare J. G., Pandey C., Mulik R. S., Mahapatra M. M., Narang H. K.
Archives of Metallurgy and Materials
|
2018
|
Vol. 63, iss. 4
1725--1734
EN
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 Xray 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.
3
Content available Characterization of weld fusion zone for TIG welded P91and P92 steels
Pandey C., Mahapatra M. M., Kumar P., Kumar P., Thakare J. G.
Archives of Metallurgy and Materials
|
2018
|
Vol. 63, iss. 4
1755--1761
EN
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 δ ferrite formation that led to the great variation in hardness of the P92 FZ. The homogeneous microstructure (absence of δ ferrite) and acceptable hardness was observed after the PWNT treatment for both the welded joint.
4
Content available A Comparative Study of Residual Stress and Mechanical Properties for FSW and TIG Weld on Structural Steel
Chaurasia P. K., Pandey C., Giri A., Saini N., Mahapatra M. M.
Archives of Metallurgy and Materials
|
2018
|
Vol. 63, iss. 2
1019--1029
EN
Mechanical properties and residual stresses of friction stir welded and autogenous tungsten inert gas welded structural steel butt welds have been studied. Friction stir welding (FSW) of structural steel butt joints has been carried out by in-house prepared tungsten carbide tool with 20 mm/min welding speed and 931 rpm tool rotation. Tungsten inert gas (TIG) welding of the butt joints was carried out with welding current, arc voltage and the welding speed of 140 amp, 12 V and 90 mm/min respectively. Residual stress measurement in the butt welds has been carried out in weld fusion zone and heat affected zone (HAZ) by using blind hole drilling method. The magnitude of longitudinal residual stress along the weld line of TIG welded joints were observed to be higher than friction stir welded joint. In both TIG and FSW joints, the nature of longitudinal stress in the base metal was observed to be compressive whereas in HAZ was observed to be tensile. It can be stated that butt welds produced with FSW process had residual stress much lower than the autogenous TIG welds.
5
Content available remote A comparative study of transverse shrinkage stresses and residual stresses in P91 welded pipe including plasticity error
Pandey C., Mahapatra M. M., Kumar P.
Archives of Civil and Mechanical Engineering
|
2018
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Vol. 18, no. 3
1000--1011
EN
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.
6
Content available remote A brief study on δ-ferrite evolution in dissimilar P91 and P92 steel weld joint and their effect on mechanical properties
Pandey C., Mahapatra M. M., Kumar P., Saini N., Thakre J. G., Vidyarthy R. S., Narang H. K.
Archives of Civil and Mechanical Engineering
|
2018
|
Vol. 18, no. 3
713--722
EN
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 δ-ferrite patches in weld fusion zone and heat affected zones (HAZs) of welded joints. The evolution of δ-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 δ-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.
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