[en] In this talk, the metallurgical considerations in weld repair of investment castings in a Russian-origin nickel-base superalloy XH43 (nominal composition in wt. %: Ni-34Fe-14Cr- 1.5Mo-0.5C-2.5Nb-1.8Ti-0.5Al) will be discussed. The hot cracking behavior of alloy XH43 in as-cast and homogenized (1130 °C/3h/air cooling) conditions will be analyzed based on longitudinal Varestraint and Gleeble hot ductility test data and detailed microstructural observations. It will be shown that satisfactory weld repair of alloy XH43 castings calls for a judicious choice of pre- and post-weld heat treatments as well as filler metal. (author)

[en] Welding is the lifeline on which a variety of industries, ranging from infrastructure and paper and pulp industries to nuclear power, chemical, petrochemical, space and defence survive. The key to the success of these industries lies in the soundness of the welds, production of which require maintenance of high quality standards. Welding was known to the ancient man in the form of forge welding. However, welding, as a technology, grew only with the advent of electricity. Subsequently, a number of fundamental principles of physics, such as electric resistance, friction, magnetism, laser and electron energy, ultrasound, microwave etc. were used to develop a number of welding processes. This conference focusses on these and such issues relevant to welding industry. Papers relevant to INIS are indexed separately

[en] Microstructure and creep fracture characteristics were examined of IN740H and P92 dissimilar welded joint for power plant. Welded joint made by GTAW (Gas Tungsten Arc Welding) and SMAW (Shielded Metal Arc welding) with AWS Class ERNiCr-3 and ENiCrFe-3 filler material and then applied post weld heat treatment. Regardless of the test conditions, fracture location was heat affected zone of P92 side and also, with increasing lMP (larson Miller Parameter), fracture location changed from weld fusion line to Type IV region. Fusion line crack is related to microstructural change due to dilution of chemical component and Type IV crack is related to deformation concentration of FGHAZ and low hardness. (author)

[en] In the present work, AISI 304 stainless steel sheets are laser welded in but the joint configuration using a robotic control 600W pulsed Nd:YAG laser system. The objective of the work is of twofold. Firstly, the study aims to find out the effect of incident angle on the weld pool geometry, microstructure and tensile property of the welded joints. Secondly, a set of experiments are conducted, according to response surface design, to investigate the effects of process parameters, namely, incident angle of laser beam, laser power and welding speed, on ultimate tensile strength by developing a second order polynomial equation. Study with three different incident angle of laser beam 89.7 deg, 85.5 deg and 83 deg has been presented in this work

[en] I am associated with design, development and commissioning of engineering systems for R and D related to nuclear fuel cycle technology. The work is targeted to product development involving conceptualization, design, technology development, testing and deployment of the product in plant. My work encompasses (a) Thin wall welding technology and automation in remote environment for fabrication of nuclear fuel pins for reactor (b) Fabrication of large size stainless steel boxes, enclosures, pressure vessels, complex piping etc and (c) Automation and development of precision engineering. systems involving welding and fabrication. I have presented few challenging contributions spanning from development of welding automation that are mechanically complex which required synergic integration with R and D on welding in remote hostile radiation environment. I have also discussed the technology development and standardization process towards manufacturing of glove boxes, enclosures, complex welded structures etc for fuel cycle facilities. The work of welding and fabrication in the nuclear industry is not restricted to heavy sections, but also thin wall components down to 0.45mm for fuel pins which are more critical for reactor operation and nuclear safety. The procedures differ over the range but what is common is the very high standard of integrity demanded for reasons of safety. (author)

[en] A piping facility which is under construction uses boiling nitric acid of around 8-11.5 M as process fluid. Austenitic stainless steel type 304L with controlled chemistry is used as material of construction due to its inherent corrosion resistance and ease of fabricability. To meet the design and process requirements, nonstandard big bore pipes are specified for certain areas with outside diameter ranging from 250 mm to 750 mm and wall thickness ranging from 3 to 8 mm, These nonstandard size pipes are fabricated by rolling 304L plates and subsequent joining by welding. This paper describes the optimisation of welding pararneters and development of Tri-cathode technique for the welding of SS304L rolled plates, qualification of welding procedure to meet the ASME Section IX requirements, in addition to the stringent corrosion testing requirements. Almost 3500 m long longitudinal seam welds have berm successfully fabricated meeting the stringent testing and qualification requirements and by employing surface as well volumetric NOT examinations. This paper covers the tangible benefits of using the Tri-cathode technique in comparison with the conventional fusion welding techniques with the addition of filler metal

[en] Alloy 617M and 10%Cr ferritic-martensitic steel are candidate rotor materials under consideration for steam turbine of India Advanced Ultra Super Critical (AUSC) coal fired power plants. Therefore, there is a dissimilar metal welding (DMW) between 10% Cr steel rotor parts to Alloy 617M rotor parts. This DMW will be executed by hot-wire narrow-gap TIG welding process using Alloy 617 filler (ERNiCrCoMo-1) wire. Narrow- Gap TIG (NGTIG) welding is carried out using specially designed TIG torch on a narrow-groove joint preparation. Welding procedure has been developed for joining 10%Cr steel to Alloy 617M by two methodologies. Ferrite grain size at weld nugget was finer compared to the base metal. Heat-affected zone also experienced phase transformation and exhibited enhancement in ferrite grain size in comparison to base metal with marginal drop in microhardness. From this investigation, it is concluded that the tool exhibited microstructural stability at elevated temperatures and thus dynamic recrystallisation was also achieved during FSW process

[en] P91 steel was widely used in the fabrication of pressure vessels and also used as structural material in nuclear power plants. Gas tungsten arc welding was widely used for joining of modified 9Cr-1Mo steel. For P91 steel welds, minimum requirement of toughness of 47 Joules at 20°C to be met so that brittle fracture can avoided during hydrotesting of vessels. Filler composition influences the microstructure evolution and mechanical properties of P91 steel welds. Among the elements present in P91 steel, Mn+Ni content influences toughness and also PWHT cycle of weldments. The objective of the present work is to study the influence of low nickel (0.09 wt. %) filler wire on microstructure and mechanical properties of weldments in as-weld and PWHT conditions. The lower critical temperature of weld was 861°C as predicted by JMatpro analysis

[en] Tungsten Inert Gas (TIG) welding process has traditionally been the most widely used process for joining high temperature alloys such as Stainless Steels, Titanium alloys and Nickel base alloys. The drawbacks of TIG welding process are the high heat input leading to distortion, porosity from trapped shielding gases and low welding speeds due to the limited power of the torch and wide arc leading to low penetration. It is for these reasons that 'keyhole' welding processes such as Laser Beam Welding (LBW) and Electron Beam Welding (EBW) have been developed, which use a more concentrated (and lower overall) heat input, and fully penetrate the material being joined. These tend to result in less thermal distortion, a narrower heat affected zone (HAZ) and fusion zone, all of which are beneficial to mechanical properties. The paper validates the InterPulse TIG technique as a viable process for welding of high temperature alloys such Stainless Steels, Titanium alloys and Nickel base alloys through microstructural and microtextural characterisation. The principal objective of this paper is to show that technically sound welds could be produced using IPTIG welding process for the high temperature alloys

[en] The components of steam generators are often subjected to repeated thermal stresses due to temperature gradients that occur on heating and cooling during start-ups and shut-downs or during temperature transients that may result in situations like low cycle fatigue (LCF) and creep-fatigue interaction (CFI). Hence, LCF and CFI are important considerations in the design of steam generator (SG) components. Since welding is unavoidable in large components such as SG,a complete understanding of the deformation mechanism occurring in weld joints under service condition is crucial. Welds frequently represent weak link in a component, both microstructurally and mechanically. In this work, role of stress relaxation (SR) under CFi shall be also highlighted because SR is an often-neglected parameter but can be effectively used to understand and predict the CFI behavior of P91 weld joint. SR is directly related with the duration of hold, strain amplitude and the direction of application of hold. In the present study, SR has been found to be inversely related with the fatigue life. A double logarithmic plot between the amount of stress relaxation versus fatigue life has been proposed, similar to the well-established Coffin-Manson plot. Ferritic steels undergo microstructural changes that are very different from the austenitic alloys. In this work, role of stress relaxation (SR) under CFi shall be also highlighted because SR is an often-neglected parameter but can be effectively used to understand and predict the CFI behavior of P91 weld joint. 5R is directly related with the duration of hold, strain amplitude and the direction of application of hold. In the present study, SR has been found to be inversely related with the fatigue life. A double logarithmic plot between the amount of stress relaxation versus fatigue life has been proposed, similar to the well-established Coffin-Manson plot