A B C D E F G H I J K L M N O P Q R S T U V W X Y Z All
Murugan, S.
- Development of Brazed Joints Using Induction Heating System for High Temperature Nuclear Applications
Authors
1 Group for Remote Handling, Robotics, Irradiation. Experiments and Post Irradiation Examination (GRIP), Metallurgy and Materials Group (MMG), Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam- 603 102, Tamilnadu, IN
Source
Indian Welding Journal, Vol 44, No 2 (2011), Pagination: 43-53Abstract
Fabrication of instrumented capsule for irradiation experiments for evaluating the irradiation performance of fuel and structural materials in a nuclear reactor requires development of thin-walled joints capable of withstanding high temperature and internal pressure. Instrumented capsules are being developed in IGCAR for irradiation of fuel and structural material specimens in Fast Breeder Test Reactor (FBTR). Instrumented capsule for irradiation of fuel pin specimen will have thermocouple of diameter 1 to 1.5 mm passing through the end plug of the fuel pin in a leak tight manner to prevent the release of fission gases generated in the fuel pin that may reach a pressure upto 10 MPa at 550°C during reactor operation. Out of the various joining methods, development of high temperature brazed joint method is found to be beneficial with respect to sealing the thermocouple passing through the end plug of the fuel pin and the intermediate plug of the irradiation capsule. Furnace and induction brazing methods have been tried and induction brazing method is seen to be more suitable for the present application. A procedure has been established to properly orient and braze the thermocouples in stainless steel plugs representing end plug and intermediate plug. Brazing parameters like temperature, time, vacuum level, and the brazing gap width are important factors in achieving good quality brazing joints. The trials carried out and the results obtained are discussed in this paper.
Keywords
Instrumented Fuel Irradiation Capsule, High Temperature Brazing, Induction Heating.
- Laser Welding of Precision Engineering Components
Authors
1 Group for Remote Handling, Robotics, Irradiation Experiments and Post Irradiation Examination (GRIP), Metallurgy and Materials Group (MMG), Indira Gandhi Centre for Atomic Research (IGCAR) Kalpakkam- 603 102, IN
Source
Indian Welding Journal, Vol 44, No 2 (2011), Pagination: 54-59Abstract
Laser beam welding (LBW) with its high power density produces narrow and deep welds with a small heat-affected zone. Nd-YAG laser has been used extensively in the fabrication of small precision components at Indira Gandhi Centre for Atomic Research (IGCAR). Some important laser welding works carried out are related to Eddy Current based Position Sensor (ECPS) and Sodium Leak Detector (SLD) in Diverse Safety Rod Drive Mechanism (DSRDM) of Prototype Fast Breeder Reactor (PFBR), and components for Ir-192 High Dose Rate (HDR) source for Board o f Radiation and Isotope Technology (BRIT). ECPS is being designed to incorporate in the DSRDM to provide a measurement on signal which indicates that all the safety rods are dropped in case of a reactor scram signal. Mineral insulated (MI) cable of 1 mm diameter used as the eddy current coil in the ECPS has been terminated with suitable end configuration using laser welding. SLD is housed inside the electromagnet assembly of DSRDM to indicate if there is any leakage of sodium into the electromagnet. The fabrication of SLD requires precision laser welding of a few of its components. For the indigenous development of Ir-192 source assembly for use in HDR Branchy therapy, the feasibility study has been carried out for the fabrication of the miniature source holder by laser welding process. This paper discusses the techniques followed in the successful fabrication of above mentioned variety of intricate components used in critical applications.
Keywords
Nd-YAG Laser Welding, Precision Components, PFBR, ECPS, DSRDM, Sodium Leak Detector, HDR Source.- Prediction of Weld Penetration in Circular Laser Welds of Ferritic Steel (P91) Material
Authors
1 Water & Steam Chemistry Division, Chemistry Group, Bhabha Atomic Research Centre, Kalpakkam, IN
2 IDEAS
3 Materials Technology Division, Metallurgy & Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, IN
Source
Indian Welding Journal, Vol 46, No 2 (2013), Pagination: 54-66Abstract
Any weld designer will always try to design a weld joint with as much low heat input as possible, at the same time obtain a good depth of penetration and in the process maintain minimum heat affected zone. When a tube or a rod has to be welded using a process and if a design analysis can be done, prior to freezing of the design, to find the depth of penetration, then it may raise the confidence level of the weld design. By this way we can avoid wasting time in carrying out random trials. In the present work an approximate method of predicting the depth of penetration during welding over the peripheral of a circular rod has been formulated under Laser Welding Process. This method will be helpful to design the joint with enhanced efficiency and with lesser probability of defects like lack of penetration and excess penetration. In the analysis ‘Thermal Explosion” theory has been used to predict the depth of penetration to map the fusion zone of a circular weld joint on P91 rod. The calculated depth of penetration has been compared with the measured depth of penetration on the weld carried out on a rod using Laser Welding process and the results were found to be nearly matching. It has been found that the depth of penetration increases as the welding progresses over the rod and the difference between the depth of penetration between starting & ending points is around a few microns. This is due to the buildup of heat in the cross section of the rod as the weld progresses.
- Residual Stress Analysis in Weldments-Theoretical Approach
Authors
1 Metallurgy and Materials Group Indira Gandhi Centre for Atomic Research, Kalpakkam, IN
2 Department of Mechanical Engineering Indian Institute of Technology, Powai, Bombay, IN
Source
Indian Welding Journal, Vol 29, No 4 (1996), Pagination: 7-23Abstract
Residual stresses are self equilibrating stresses existing in materials or components under uniform temperature conditions. When two pieces of plates/pipes are joined together by welding, localised residual stresses coupled with shrinkage are generated in the vicinity of the weld. The presence of these residual stresses can be detrimental to the strength of the joint. Tensile residual stresses are generally detrimental, increasing the susceptibility of a weld to fatigue damage, stress corrosion and fracture. During welding, temperature conditions range from melting point of the material to room temperature. Mechanical and thermal properties of the material are temperature dependent and this change with temperature during the welding process. The material stress-strain behaviour is elastic-plastic and temperature dependent. Thermal stresses are produced in the material during the process of heating and cooling. When the material is cooled to room temperature, the locked up stresses present in the material are retained residual tresses.- Importance of Thermophysical Properties of Materials in Thermal Modelling of Welds
Authors
1 Metallurgy and Materials Group Indira Gandhi Centre for Atomic Research. Kalpakkam, IN