In this study, a pair of X40CrMoV5 1 (H13) hot working tool steel and Ç1030 (SAE1030) plain carbon steel were welded to each other by using flash butt welding method. During the experimental study the pressure was set to 2 bars and upsetting current times were chosen as 1,6; 1,8 and 2 seconds. The suitable welding parameters were chosen by examining the effect of welding parameters on microstructures and mechanical properties of materials. Experimental results showed that welding exhibited the highest hardness was measured from joining interface of Ç1030 steel, while it was in the coarse grained region of H13 steel. It was also found that hardness values decreased with increasing upseting current time. Tensile test results showed that fracture was occured (in the main material) at C1030 steel side.