الفهرس 
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Abstract
Stainless steel are structural materials used in conventional and nuclear power generating plants.
Stainless steels are used as cladding material for pressure vessels.
Stainless steels are used also in coolant piping of pressueized water reactors and valve bodies.
Welding techniques are used for repairing and replacing the components of th nuclear reactors.
The purpose of this work is to evaluate the microstructure, mechanical properties and corrosion resistance of two types of austentitic stainless steels(304L, 316L) and one type of duplex stainless steel at different conditions for base and weld metals.
For welding processes austenitic stainless steel electrode types E308L, E316L, ER316L, ER308LSi, and E2209, ER2209 were used to join 304L, 316L, and duplex stainless steels (DSS).
Welding of specimens was conducted using Shield Metal Arc Welding (SMAW), and Tungsten Inert Gas (TIG) processes.
Charpy-V- notch impact properties were determind at ambient temperature for base and weld metals before and after heating at 475, 650 750 and 850*C for 3hr.
Impact energy of base metls and weld metals were also determind for the three types at cryogenic temperatures
of -50, -100, -150 and -196C.
The ferrit content of the base and weld metals berfore and after heating were measured.
Vickeres micro-hardness profiles across the bas metal, heat affected zone, and weld metal (BM, HAZ, WM)
before and after heating for austenitic types stainless steels and duplex stainless steel was performed.
The electrochemical tests for the three types of stainless steel weld metals were performed in two media; 2400ppm boric acid solution containing 4ppm lithium hydroxide and 1%NaCI solution .
Optical and scanning electron microscoppes were used to characterize the microstructure and fracture surface
morphology.
The results revealed the influence of precipitation of secondary phases, due to heating on ferrite content, micro-hardness, impact toughness, and corrosion resistance of the investigated stainless steels.
Heating decreased the impact energy of 316L and duplex base and wed metals while those of 304L were not much affected.