Kapoor, K.; Prahlad, B.
Stainless Steel Alloy D9 is the material for cladding in various sub-assemblies of Prototype Fast Breeder Reactor (PFBR). The fabrication, inspection, testing and supply of the clad tubes for the first core of PFBR is nearly completed. The paper also compares the specification requirements and the achieved results for some of the critical aspects which is arrived after completing supply against the first core requirement
Joseph, Jojo; Ramachandran, Divakar; Venkiteswaran, C. N.; Karthik, V.; Johny, T.; Rao, B. P. C.; Jayakumar, T.
A test fuel sub-assembly (FSA) with 37 fuel pins consisting of annular MOX fuel pellets encapsulated in Alloy D9 cladding and wrapper simulating the fuel design of the Prototype Fast Breeder Reactor (PFBR) was irradiated to a peak burn-up of 112 GWd/t in the FBTR and subjected to post-irradiation examination (PIE) at the Radiometallurgy Laboratory (RML) of IGCAR. The investigations consisted of non-destructive and destructive tests designed to evaluate the performance of the fuel and structural materials. Moderate fuel swelling and fission gas release of around 85% was observed. Non-destructive tests gave indications of changes in the central hole dimensions of the fuel pellet and Fuel-Clad Chemical Interaction (FCCI) and these were confirmed by metallographic sections. Initiation of FCMI was also revealed at the core top locations. The Alloy D9 cladding and wrapper have performed satisfactorily with respect to swelling resistance and residual mechanical properties up to the maximum displacement damage of about 60 dpa that has been attained in the FBTR. The results give confidence to operate PFBR with the designated fuel design. (author)
Mandal, Sumantra; Sivaprasad, P. V.; Dube, R. K.
An artificial neural network (ANN) model was developed to predict the microstructural evolution of a 15Cr-15Ni-2.2Mo-Ti modified austenitic stainless steel (Alloy D9) during dynamic recrystallization (DRX). The input parameters were strain, strain rate, and temperature whereas microstructural features namely, %DRX and average grain size were the output parameters. The ANN was trained with the database obtained from various industrial scale metal-forming operations like forge hammer, hydraulic press, and rolling carried out in the temperature range 1173-1473 K to various strain levels. The performance of the model was evaluated using a wide variety of statistical indices and the predictability of the model was found to be good. The combined influence of temperature and strain on microstructural features has been simulated employing the developed model. The results were found to be consistent with the relevant fundamental metallurgical phenomena.
Sudha, R.; Muralidaran, P.; Ganesan, V.; Periaswami, G.
This paper describes an application of tracer technique in determining the diffusion coefficient of 54 Mn in alloy D9 and AISI type SS 316 LN and, subsequently, its use in decontamination studies using suitable inorganic acid mixtures
Raj, Baldev; Jayakumar, T.; Bhaduri, A.K.; Mandal, Sumantra [Indira Gandhi Centre for Atomic Research, Kalpakkam (India)
Fast Breeder Reactors (FBRs) are vital towards meeting security and sustainability of energy for the growing economy of India. The development of FBRs necessitates extensive research and development in domains of materials and manufacturing technologies in association with a wide spectrum of disciplines and their inter-twining to meet the challenging technology. The paper highlight the work and the approaches adopted for the successful deployment of materials, manufacturing and inspection technologies for the in-core and structural components of current and future Indian Fast Breeder Reactor Programme. Indigenous development of in-core materials viz. Titanium modified austenitic stainless steel (Alloy D9) and its variants, ferritic/martensitic oxide-dispersion strengthened (ODS) steels as well as structural materials viz. 316L(N) stainless steel and modified 9Cr-1Mo have been achieved through synergistic interactions between Indira Gandhi Centre for Atomic Research (IGCAR), education and research institutes and industries. Robust manufacturing technology has been established for forming and joining of various components of 500 MWe Prototype Fast Breeder Reactor (PFBR) through 'science-based technology' approach. To achieve the strict quality standards of formed parts in terms of geometrical tolerances, residual stresses and microstructural defects, FEM-based modelling and experimental validation was carried out for estimation of spring-back during forming of multiple curvature thick plantes. Optimization of grain boundary character distribution in Alloy D9 was carried out by adopting the grain boundary engineering approach to reduce radiation induced segregation. Extensive welding is involved in the fabrication of reactor vessels, piping, steam generators, fuel sub-assemblies etc. Activated Tungsten Inert Gas Welding process along with activated flux developed at IGCAR has been successfully used in fabrication of dummy fuel subassemblies (DFSA) required
Kukreja, L. M.; Paul, C. P.; Kumar, Atul; Kaul, R.; Ganesh, P.; Rao, B. T.
Laser is undoubtedly one of the most important inventions of the twentieth century. Today, it is widely deployed for a cornucopia of applications including materials processing. Different lasers such as CO2, Nd:YAG, excimer, copper vapor, diode, fiber lasers, etc., are being used extensively for various materials processing applications like cutting, welding, brazing, surface treatment, peening, and rapid manufacturing by adopting conventional and unconventional routes with unprecedented precision. In view of its potential for providing solution to the emerging problems of the industrial materials processing and manufacturing technologies, a comprehensive program on laser materials processing and allied technologies was initiated at our laboratory. A novel feature-based design and additive manufacturing technologies facilitated the laser rapid manufacturing of complex engineering components with superior performance. This technology is being extended for the fabrication of anatomically shaped prosthetics with internal heterogeneous architectures. Laser peening of spring steels brought significant improvement in its fatigue life. Laser surface treatments resulted in enhanced intergranular corrosion resistance of AISI 316(N) and 304 stainless steel. Parametric dependence of laser welding of dissimilar materials, AISI 316M stainless steel with alloy D9, was established for avoiding cracks under optimum processing conditions. In the domain of laser cutting and piercing, the development of a power ramped pulsed mode with high pulse repetition frequency and low duty cycle scheme could produce highly circular, narrow holes with minimum spattered pierced holes. A review of these experimental and some theoretical studies is presented and discussed in this chapter. These studies have provided deeper insight of fascinating laser-based materials processing application for industrial manufacturing technologies.
Gary S. Was; Brian D. Wirth
Major accomplishments of this project were the following: 1) Radiation induced depletion of Cr occurs in alloy D9, in agreement with that observed in austenitic alloys. 2) In F-M alloys, Cr enriches at PAG grain boundaries at low dose (<7 dpa) and at intermediate temperature (400°C) and the magnitude of the enrichment decreases with temperature. 3) Cr enrichment decreases with dose, remaining enriched in alloy T91 up to 10 dpa, but changing to depletion above 3 dpa in HT9 and HCM12A. 4) Cr has a higher diffusivity than Fe by a vacancy mechanism and the corresponding atomic flux of Cr is larger than Fe in the opposite direction to the vacancy flux. 5) Cr concentration at grain boundaries decreases as a result of vacancy transport during electron or proton irradiation, consistent with Inverse Kirkendall models. 6) Inclusion of other point defect sinks into the KLMC simulation of vacancy-mediated diffusion only influences the results in the low temperature, recombination dominated regime, but does not change the conclusion that Cr depletes as a result of vacancy transport to the sink. 7) Cr segregation behavior is independent of Frenkel pair versus cascade production, as simulated for electron versus proton irradiation conditions, for the temperatures investigated. 8) The amount of Cr depletion at a simulated planar boundary with vacancy-mediated diffusion reaches an apparent saturation value by about 1 dpa, with the precise saturation concentration dependent on the ratio of Cr to Fe diffusivity. 9) Cr diffuses faster than Fe by an interstitial transport mechanism, and the corresponding atomic flux of Cr is much larger than Fe in the same direction as the interstitial flux. 10) Observed experimental and computational results show that the radiation induced segregation behavior of Cr is consistent with an Inverse Kirkendall mechanism.
Kaul, R.; Nath, A.K.
Laser processing, because of its characteristic features, often gives rise to unique microstructure and properties not obtained with other conventional processes. We present various diverse laser processing case studies involving control of microstructure through judicious selection of processing parameters carried out with indigenously developed high power CO 2 lasers. The first study describes microstructural control during end plug laser welding of PFBR fuel pin, involving crack pone alloy D9 tube and type 316 M stainless steel (SS) plug, through preferential displacement of focused laser beam. Crater and associated cracks were eliminated by suitable laser power ramping. Another case study describes how low heat input characteristics of laser cladding process has been exploited for suppressing dilution in 'Colomony 6' deposits on austenitic SS. The results are in sharp contrast to extensive dilution noticed in Colmony 6 hard faced deposits made by GTAW. A novel laser surface melting (LSM) treatment for type 316 (N) SS weld metal has been developed to generate a sensitization-resistant microstructure which leads to enhanced resistance against intergranular corrosion (IGC). IGC resistance of laser treated surface has been found to be critically dependent on laser processing parameters. Experimental observations have been analyzed with thermal simulation. We have also studied the effect of laser beam spatial intensity profile on the microstructure in LSM. We have developed laser-assisted graded hard facing of austenitic SS substrate with Stellite 6 which, in contrast to direct deposition either by laser or GTAW, produced smooth transition in chemical composition and hardness used to control grain coarsening and martensite formation in type 430 SS weldment. Laser rapid manufacturing (LRM) is emerging as a new rapid and cost effective process for low volume fabrication, esp. of expensive materials. The talk will also present microstructural characteristics of laser
Raj, B.; Rao, B.S.
excellent understanding of type IV cracking in the heat affected zone of 9Cr1Mo steel weldments, factors influencing hot cracking in 316L (N) welds and weldments, measures to be taken for prevention of hydrogen assisted cracking and achieving adequate toughness in the weld metal of Mod.9Cr1Mo and production of dissimilar weld joints between Mod.9Cr1Mo and 316L (N) stainless steels. All this experience could be utilized in the fabrication of sound components for fusion reactors. Robust ANN models have been developed for alloy development, thermomechanical processing, for prediction of creep-fatigue life, radiation damage and delta-ferrite in austenitic stainless steel welds. Extensive investigations by electron microscopy have led to understanding fundamental mechanisms associated with radiation damage in 316 SS and Alloy D9. The concept of Phase evolution diagrams has been developed for the prediction of remnant life of ferritic steel components based on the evolving microstructure. Grain Boundary Engineering (GBE) is being pursued as an innovative processing technique to tailor the properties of the existing alloys by producing higher number of coincident site lattice boundaries that lead to greater resistance to intergranular degradation against fracture, cavitation and localized corrosion, higher creep resistance and possibly higher radiation damage resistance. Experimental and modeling work done on GBE of austenitic and ferritic steels will be presented. Various Non Destructive Examination techniques and procedures have been developed for ensuring quality of the nuclear grade steels with respect to inclusion content, qualification of microstructure, mechanical properties, determination of residual stresses, and early detection and evaluation of damage in materials and components, in service. The adoption of suitable NDE techniques and methodologies would facilitate to obtain deeper insights into the development of materials, fabrication techniques and assessment of