The paper presents the results of quality evaluation of weldments produced by a mutual combination of different steel grades. Weld joints were made using GMAW technology (method -135 ISO 4063). The type of welding parameters used for the quality of welded joints was monitored. The quality of welded joints was assessed using non-destructive tests. In non-destructive tests, the Visual test according to EN ISO 17637, the Penetration test with colour indication according to EN ISO 22476-12 was used to identify surface defects. The presence of internal errors was assessed by a radiation test according to EN ISO 17636-1. Within the destructive tests, the quality of the welds was assessed by a tensile test according to EN ISO 6892-1, by the test of brittleness of welds according to EN ISO 5173, the course of hardness according to EN ISO 6507-1 was determined on transverse cuts. The bending impact test according to EN ISO 9016 will determine the toughness of the weld metal and heat-affected areas. Metallographic analysis of welds according to EN ISO 17639 was performed on transverse metallographic sections using light microscopy. Based on the performed experiments, recommendations were set, or proposed changes in the welding procedures of the given steel grades.