Please use this identifier to cite or link to this item: http://localhost:8081/xmlui/handle/123456789/3665
Title: STUDIES ON FATIGUE AND FRACTURE REJr TOUGHNESS PROPERTIES OF PULSE CURRENT MIG WELDED Al-Zn-Mg ALLOY
Authors: Reddy, Y. Srikanth
Keywords: MECHANICAL & INDUSTRIAL ENGINEERING;FRACTURE REJr TOUGHNESS;PULSE CURRENT MIG WELDED;Al-Zn-Mg ALLOY
Issue Date: 1991
Abstract: Al-Zn-Mg alloy weldments were prepared using 10mm thick extruded plates (7039) and 1.6mm diameter Al+4.7Mg filler wire at a constant'- mean current level of 235 Amp. using pulsed M1G we l d i ng---pro-cess - .During welding, the p-uI se--frequency -was varied from 25 to 100Hz and the pulse duration was varied from 4.5 to 8.5ms. The weldments were also• prepared using continuous (conventional) current welding process at the same mean welding current level as used in pulsed current welding. The effect of pulse frequency and pulse duration on weldment mechanical properties such as hardness, tensile strength, fracture toughness (CTOD) and fatigue properties and on microstructure and porosity content of the weld deposit have been studied. Relatively fine morphology of weld metal has been marked in case of weldments prepared by pulse current technique as compared to the conventional one. However the extent of refinement was found to vary wl.th the variation in the pulse parameters. Porosity content of the weld deposit was found to vary with the variation in 1,/le ratio and has shown a least porosity content in the I./lb ratio range of 3.5 to 4.5. Hardness, tensile strength, fracture toughness (CTOD) and fatigue properties of weldments were found better in welds prepared with pulse current as compared to that conventional one. At a given pulse frequency the hardness and tensile strength of the weld deposit was found to be increased with the increase in pulse duration from 4.5 to 8.5 ms. and they were in good agreement with zinc pick up in the weld deposit. At a given pulse frequency the decrease in pulse duration from 8.5.to 4.5 ms. was found to enhance the CT-OD v-aiue--of -we l d--depos i t considerably as compared to CTOD value of conventional welding. At a given pulse frequency fatigue life of the weldments were found to be decreased with the increase in pulse duration from 4.5 to 8.5 ms. It was also found that the fatigue life is decreased with the increase in porosity content of the weld deposit.
URI: http://hdl.handle.net/123456789/3665
Research Supervisor/ Guide: Ghosh, P. K.
Babu, P. Nagesh
metadata.dc.type: M.Tech Dessertation
Appears in Collections:MASTERS' THESES (MIED)

Files in This Item:
File Description SizeFormat 
MIED246112.pdf3.02 MBAdobe PDFView/Open


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.