Characterization and evaluation of diffusion bonding process temperatures of AISI 1010 plain carbon steel (PCS) with AISI 430 ferritic and AISI 420 martensitic stainless steels were experimentally studied. The diffusion bonding of AISI 1010 with AISI 430/420 steel couples were held for 40 min, at 800°C–900°C–1000°C– 1100°C, under protective atmosphere, with 10 MPa load blow those that would cause macroscopic deformation to the contacting surfaces. Microstructure morphologic evaluations were carried out with the help of SEM. Shear tests and weld efficiency were calculated at interface for mechanical properties characterization. Test results and morphologic evaluations showed that under given diffusion bonding conditions, welding/bonding integrity were slightly increased at elevated temperatures and highest values were traced at 1000°–1100°C process temperatures.