Abstract
The nickel-based Colmonoy-5 hardfacing alloy is used to hard-face 316LN austenitic stainless steel components in fast reactors. The nominal composition (in wt%) was listed as follows: 0.01 C, 0.49 Si, 0.87 Mn, 17.09 Cr, 14.04 Ni, 2.56 Mo, 0.14 N, and balance Fe. Hardfacing is a technique of applying hard and wear-resistant materials to substrates that need abrasion resistance. The thickness of hardfacing deposit varies between 0.8 mm and 2 mm based on parameter combinations. In this study, laser hardfacing process parameters including laser power, powder feed rate, travel speed, and defocusing distance were optimized to reduce weight loss of laser hard-faced Ni-based deposit. The tribological characteristics of reactor-grade NiCr-B hard-faced deposits were investigated. The RSM technique was used to identify the most important control variables resulting in the least weight loss of the nickel-based alloy placed on AISI 316LN austenitic stainless steel. Statistical techniques like DoE and ANOVA are utilized. Changing the laser settings may efficiently track the weight loss of laser hard-faced nickel alloy surfaces. These are created using the response surface technique. The deposit produced with a laser power of 1314 W, powder feed rate of 9 g/min, travel speed of 366 mm/min, and defocusing distance of 32 mm had the lowest weight loss of 16.4 mg. Based on the F value, the powder feed rate is the major influencing factor to predict the hardness followed by power, travel speed, and defocusing distance.
Highlights
Prototype Fast Breeder Reactor (PFBR) is a 500 MWe pool type sodium-cooled nuclear reactor having two separate sodium circuits with the intermediate heat exchanger (IHX) providing thermal contact between the primary pool and the secondary circuit. e secondary sodium circuits transfer heat from the IHX to the steam generator (SG), the steam from which drives the conventional steam turbines. e minimum sodium temperature in the primary pool during normal operation is 400°C, while the mean above-core temperature is 550°C. e minimum and maximum sodium temperatures in the secondary circuit are 355 and 525°C, respectively. e steam temperature is 490°C at 16.6 MPa pressure
Austenitic stainless steel (SS) is the major material of construction for PFBR. e Main Vessel, Inner Vessel, GridPlate, and Primary Piping, etc., whose service temperatures are above 427°C, are made of numerous austenitic
By replacing process parameter values in the coded form, the empirical connections may be utilized to anticipate responses. e primary and interaction impacts of process factors on deposit characteristics were calculated and shown as perturbation plots in Figures 4 and 5. e perturbation plot is a diagrammatic depiction of the response surface. e perturbation plot compares the impacts of all variables in the Response Surface Method (RSM) design space
Summary
Prototype Fast Breeder Reactor (PFBR) is a 500 MWe pool type sodium-cooled nuclear reactor having two separate sodium circuits with the intermediate heat exchanger (IHX) providing thermal contact between the primary pool and the secondary circuit. e secondary sodium circuits transfer heat from the IHX to the steam generator (SG), the steam from which drives the conventional steam turbines. e minimum sodium temperature in the primary pool during normal operation is 400°C, while the mean above-core temperature is 550°C. e minimum and maximum sodium temperatures in the secondary circuit are 355 and 525°C, respectively. e steam temperature is 490°C at 16.6 MPa pressure. Laser cladding and wear testing of nickel base hardfacing materials have process parameter effects on ASTM [14]. In this study, an attempt has been made to optimize the important laser hardfacing parameters to attain maximum hardness in nickel-based hard-faced deposits on 316 LN austenitic stainless steel by RSM. E following process parameters have been identified as having a greater impact on deposit characteristics: laser power (P), powder feed rate (F), travel speed (T), and defocusing distance (D) All of these factors affect the melting and flattening of powder particles and, the deposit properties of nickel-based hardfacing. To determine the possible working limits of laser hardfacing parameters, trial runs were conducted using a 12 mm thick 316 LN austenitic stainless steel plate and nickel-based alloy powder. Identify problem and objectives of 316LN austenitic stainless steel and Nickel based alloy
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