Effect of pool geometry on the quality of TIG welded joints

ABSTRACTPhD THESISEFFECT OF POOL GEOMETRY ON THE QUALITY OFTIG WELDED JOINTSUğur EŞMEDEPARTMENT OF MECHANICAL ENGINEERINGINSTITUTE OF NATURAL AND APPLIED SCIENCESUNIVERSITY OF ÇUKUROVASupervisor : Prof. Dr. Melih BAYRAMOĞLUYear: 2006, Pages: 366Jury : Prof. Dr. Melih BAYRAMOĞLU: Prof. Dr. Necdet GEREN: Assoc. Prof. Dr. Mustafa Kemal KÜLEKCİ: Assoc. Prof. Dr. Abdülkadir EKŞİ: Assist. Prof. Dr. Ali KOKANGÜLAcross the engineering spectrum, welding is an essential process in themanufacturing of components, assemblies or complete machines. Tungsten inert gas(TIG) welding is the best known and most frequently used method of weldingprocess in food industry, ships, bridges and welding of stainless steels. Basically,TIG weld quality is strongly characterized by the weld pool geometry which hasseveral quality responses such as tensile load (TL), heat affected zone (HAZ), upperwidth (UW), upper height (UH), penetration (P) and area of penetration (AP). Weldpool geometry plays an important role in determining the mechanical properties ofthe weld. Therefore, it is very important to select the welding process parameters forobtaining an optimal weld pool geometry. In this study, the effect of TIG weldingprocess parameters (welding speed, welding current, gas flow rate and gap distance)on the weld pool shape and the quality responses were investigated. Themathematical models were developed for optimization and prediction of the weldpool geometry. Also, a neural network (NN) was used to construct the relationshipsbetween welding process parameters and weld pool geometry in TIG welding.Keywords: Tungsten Inert Gas Welding (TIG), Weld Pool Geometry, CentralComposite Design (CCD), Response Surface Methodology (RSM),Neural Network (NN)