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Bishal Silwal - Georgia Southern University. Statesboro, GA, US

Bishal Silwal Bishal Silwal

Assistant Professor, Department of Mechanical Engineering | Georgia Southern University

Statesboro, GA, UNITED STATES

Bishal Silwal is an expert in Welding and Joining, Arc Based Additive Manufacturing, and Transport Phenomenon in Material Processing.

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Biography

Dr. Bishal Silwal is affiliated to Mechanical Engineering, Georgia Southern University, where Dr. Bishal Silwal is currently working as Assistant Professor. Dr. Bishal Silwal has authored and co-authored several national and international publications and also working as a reviewer for reputed professional journals. Dr. Bishal Silwal is having an active association with different societies and academies around the world. Dr. Bishal Silwal made his mark in the scientific community with the contributions and widely recognition from honourable subject experts around the world. Dr. Bishal Silwal has received several awards for the contributions to the scientific community. Dr. Bishal Silwal major research interest involves Mechanical Engineering.

Areas of Expertise (3)

Transport Phenomenon in Material Processing

Welding and Joining

Arc Based Additive Manufacturing

Education (1)

Utah State University: Ph.D.

Articles (3)

Effect of vibration and hot-wire Gas Tungsten Arc (GTA) on the geometric shape

Journal of Materials Processing Technology

B. Silwal et al.

2017 Bead-on-plate experiments were carried out, and the weld-bead size and shape were compared and discussed. The welding droplet parameters were measured by a high-speed camera. A computation fluid dynamics (CFD) model utilizing VOF (volume of fluid) method, incorporating the experimental droplet parameters has been developed to understand the weld pool dynamics and subsequent weld pool geometry. From the experimental results, a narrower and deeper penetration was observed with hot-wire while wider and shallow penetration was observed with cold wire gas tungsten arc welding (GTAW). The developed model has been applied to predict and analyze the mechanism for narrower and deeper penetration. A modified relationship has been established for droplet detachment in hot wire GTAW.

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Creep rates of heat-affected zone of grade 91 pipe welds as determined by stress-relaxation test:

Creep rates of heat-affected zone of grade 91 pipe welds as determined by stress-relaxation test

B. Silwal et al.

2016 Cross-weld creep testing conducted at 650 °C under 69 MPa stress has reproduced either the Type I or Type IV failure mode in Grade 91 welds, depending on the post-weld heat treatment procedures. Welds post-weld heat treated below the AC1 temperature have ruptured in the Type VI failure mode, while welds heat-treated above the AC1 temperature of the alloy have ruptured in the Type I failure mode. Heat-treatments at lower temperatures and shorter durations have produced a reduced creep rate. The accelerated short term stress-relaxation test has been conducted to obtain the input creep rates for a finite element model for the cross-weld creep testing. The model predicted secondary creep rates are in good agreement with the results from the conventional cross-weld creep tests. From the finite element model, the creep damage by cavitation is believed to start at regions where the first principal stress and stress triaxiality concentrate.

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Effect of Post-weld Heat Treatment on Toughness of Heat-affect Zone of Grade 91 Steel

Welding Journal

B. Silwal et al.

2013 The impact toughness of the heat-affected zone (HAZ) for Grade 91 steel welds has been experimentally investigated. The as-welded multipass HAZ has a significant scatter in toughness, due to variations in the Charpy notch location and the path of fracture propagation. The cross-weld Charpy specimen gives a toughness value that can be attributed to contributions by the weld metal, various HAZ regions, and the base metal. The microstructure evolution of various HAZ regions during postweld heat treatment (PWHT) has been investigated and used to explain the toughness changes. A 760° for 2 h PWHT can significantly increase the cross-weld toughness of the HAZ. The measured weld HAZ toughness can be understood using a linear additive model that employs as the inputs the toughness values of various HAZ regions reproduced on the Gleeble® The toughness of the coarse-grained heat-affected zone (CGHAZ) recovers the slowest as a function of increasing PWHT temperature, and remains low until a 730° heat treatment. To guarantee an adequate HAZ toughness, a PWHT of at least 730° is recommended. Postweld heat treatment above the A C1perature will result in the formation of fresh martensite, which decreases the toughness and increases the hardness of all HAZ regions. Postweld heat treatment 20° below the AC1 temperature for 2 h has produced the highest toughness and lowest hardness of all HAZ regions.

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