In this study, AISI 1040 steel and AISI 304 austenitic stainless steel sheets with 10 mm thickness were joined by the manual gas metal arc (GMAW) and the synergic controlled pulsed (P-GMAW) welding methods. The microstructural changes, phases, and compounds occurred in the interface of welded samples were comprehensively examined by using a combination of scanning electron microscopy (SEM), microanalysis by energy dispersive spectrometry (EDS), X-Ray diffraction (XRD), and microhardness tests. To determine the mechanical properties of welded samples, notch impact strength tests were applied. In addition, fracture types in the notch impact test of samples were determined from the fractographic examinations by using SEM. At the end of these tests, the best result was obtained by the synergic controlled pulsed (P-GMAW) technique.