The aim of the object is to provide PhD students with the complex science information about the theoretical principles of welded joints formation at fusion and pressure welding, physical principles of the metal welding processes, metallurgical behavior between weld metal and slag or shielding gases, weld metal formation and weld metal crystallization principles, phase transformations in the weld joints, weld joints cracking phenomena, deformation and tension processes in the welds, materials weldability and theoretical principles of materials brazing. Based on the received information the students will be able to independently scientifically solve the task in the both the basic and applied research activities in the field of welding.