The aim of this paper is to demonstrate the application possibilities at using diffusion bonding for creation the homogenous joints regarding their strength properties in comparison with the fusion MMAW method and with the parent material. Connection was carried out for low-alloyed bainitic steel 10GN2MFA that is designed for production shells and bodies of the primary steam-generators collectors which are used in the nuclear power industry. In the paper are theoretically described the basics of diffusion. Moreover, there is described also the proposal and optimization of the diffusion bonding process parameters and optimization of the thermal treatment procedure. Experiments were carried out by means of the thermal-mechanical simulator Gleeble 3500. Welded joints were subsequently evaluated in light of mechanical properties by hardness measurement and metallography.