Investigations On Shot Peening Process For Hot Corrosion Resistance Of P22 And SS304L Steels And Their Weldments Used In Power Plants.
Kumar, Jagdish
Investigations On Shot Peening Process For Hot Corrosion Resistance Of P22 And SS304L Steels And Their Weldments Used In Power Plants. by Jagdish Kumar - IIT Jodhpur Department of Mechanical Engineering 2020 - xviii,50p. HB
"Dissimilar joints are widely used in critical locations of the power plant industry. This is done to ensure better performance output and enhanced structural integrity of the component and system as a whole. The present study investigates the hot corrosion behavior of dissimilar weld between P22/SS304L steel commonly used in high- temperature boilers. The weld is fabricated using the GTAW process employing ER309L filler. Argon shielding gas at flow rate 15L/min was used with welding parameters being 170A current and 15V voltage. The fabricated weld has been characterized for mechanical properties of tensile strength and microstructural investigations. The major thrust of this thesis is the high-temperature oxidation behavior of employed base metals and fabricated weld joint. The base metals P22, SS304L, and their weld joints were exposed to 50 high-temperature cycles at 600°C and 700°C in the environment of sodium chloride (NaCl), sodium sulfate (Na2SO4) and vanadium oxide (V2O5) in different combinations. To study the effect of shot peening on reducing the corrosion susceptibility, the specimens were shot-peened with varying distance and blasting time and then examined for hot corrosion behavior. The weight gain (Thermogravimetric analysis)analysis was performed to estimate the weight change of specimen after 50 cycle study. The oxide scale was also characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM).The fabricated weld has a tensile strength of 499.81 MPa which comparable to the tensile strength of P22 (530 MPa) and SS304L (515 MPa). Microstructure reveals no significant inclusion present. Hot corrosion experiment results indicate that maximum corrosion was observed in the environment of 50%Na2SO4+50%NaCl molten salt at temperature 700°C. Oxidation kinetics behavior of steels with salt mixture analyzed by parabolic kinetic equation indicates the growth of the protective oxide layer decreases with time. The weight gain behavior comparison between SS304L and P22 shows that P22 steel weight gain followed the parabolic curve better as compared to SS304L steel. The weld zone weight gain per area was observed less than that of the base material P22 and SS304L. This indicates that the rate of oxidation decreases with increases in Cr content in the steel. Cr favors the formation of a protective inner scale of chromium oxide (Cr2O3). Shot peening was found to enhance the hot corrosion resistance by a maximum amount of 33.79%. The oxide phases were observed majorly as Fe2O3 and minor presence of Fe3O4, Cr2O3, and FeS2. Thicker and heavy oxide scaling was observed in P22 with higher adhering tendency, whereas the scale in SS304L was exfoliated from the surface of the substrate and the scale was very thin in appearance. Electron dispersion spectroscopy (EDS) was performed for distinctive regions of the substrate and oxide scales. There was a sharp contrast in the chemical composition of these regions. This invariably leads to a difference in mechanical behavior. This study concludes the hot corrosion behavior of base metals P22,SS304L, their weld along with studying the influence of shot peening on high-temperature corrosion resistance.
"
Shot Peening Process For Hot Corrosion Resistance Of P22 And SS304L Steels
MTech Theses
Department of Mechanical Engineering
620.112 / K963I
Investigations On Shot Peening Process For Hot Corrosion Resistance Of P22 And SS304L Steels And Their Weldments Used In Power Plants. by Jagdish Kumar - IIT Jodhpur Department of Mechanical Engineering 2020 - xviii,50p. HB
"Dissimilar joints are widely used in critical locations of the power plant industry. This is done to ensure better performance output and enhanced structural integrity of the component and system as a whole. The present study investigates the hot corrosion behavior of dissimilar weld between P22/SS304L steel commonly used in high- temperature boilers. The weld is fabricated using the GTAW process employing ER309L filler. Argon shielding gas at flow rate 15L/min was used with welding parameters being 170A current and 15V voltage. The fabricated weld has been characterized for mechanical properties of tensile strength and microstructural investigations. The major thrust of this thesis is the high-temperature oxidation behavior of employed base metals and fabricated weld joint. The base metals P22, SS304L, and their weld joints were exposed to 50 high-temperature cycles at 600°C and 700°C in the environment of sodium chloride (NaCl), sodium sulfate (Na2SO4) and vanadium oxide (V2O5) in different combinations. To study the effect of shot peening on reducing the corrosion susceptibility, the specimens were shot-peened with varying distance and blasting time and then examined for hot corrosion behavior. The weight gain (Thermogravimetric analysis)analysis was performed to estimate the weight change of specimen after 50 cycle study. The oxide scale was also characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM).The fabricated weld has a tensile strength of 499.81 MPa which comparable to the tensile strength of P22 (530 MPa) and SS304L (515 MPa). Microstructure reveals no significant inclusion present. Hot corrosion experiment results indicate that maximum corrosion was observed in the environment of 50%Na2SO4+50%NaCl molten salt at temperature 700°C. Oxidation kinetics behavior of steels with salt mixture analyzed by parabolic kinetic equation indicates the growth of the protective oxide layer decreases with time. The weight gain behavior comparison between SS304L and P22 shows that P22 steel weight gain followed the parabolic curve better as compared to SS304L steel. The weld zone weight gain per area was observed less than that of the base material P22 and SS304L. This indicates that the rate of oxidation decreases with increases in Cr content in the steel. Cr favors the formation of a protective inner scale of chromium oxide (Cr2O3). Shot peening was found to enhance the hot corrosion resistance by a maximum amount of 33.79%. The oxide phases were observed majorly as Fe2O3 and minor presence of Fe3O4, Cr2O3, and FeS2. Thicker and heavy oxide scaling was observed in P22 with higher adhering tendency, whereas the scale in SS304L was exfoliated from the surface of the substrate and the scale was very thin in appearance. Electron dispersion spectroscopy (EDS) was performed for distinctive regions of the substrate and oxide scales. There was a sharp contrast in the chemical composition of these regions. This invariably leads to a difference in mechanical behavior. This study concludes the hot corrosion behavior of base metals P22,SS304L, their weld along with studying the influence of shot peening on high-temperature corrosion resistance.
"
Shot Peening Process For Hot Corrosion Resistance Of P22 And SS304L Steels
MTech Theses
Department of Mechanical Engineering
620.112 / K963I