In recent years, some topics in Automotive industry has become important such as energy saving, carbon emission and automotive safety issues. The main motivation to meet these requirements is employing high strength and low weight materials for vehicles. Therefore, the conventional materials have been substituted with Advanced High Strength Steels (AHSS) and High Strength Low Alloy (HSLA) steels that have high strength-to-weight ratios. However, in addition to material investigation, the joining and welding of these materials is of high importance cannot be underestimated. In this work, weldability of TRIP 800 (transformation induced plasticity), a AHSS steel, and microalloyed steels, a HSLA steel, with resistance spot welding has been investigated. The effect of welding time parameter on tensile-shear properties was analyzed. The optimum parameters for tensile-shear strengths and the encountered separation modes have been examined. The highest tensile-shear loads was obtained using 15 periods. C1 [Ozsarac, Ugur; Ozen, Fatih; NuriAkkas; Aslan, Haci; Aslanlar, Salim] Sakarya Univ Appl Sci, Fac Technol, Serdivan Sakarya, Turkey. [Onar, Volkan] Pamukkale Univ, Fac Technol, Mech & Mfg Engn Dept, Denizli, Turkey. [Ozen, Fatih] Batman Univ, Fac Technol, Mech & Mfg Engn Dept, Batman, Turkey. [Aslanlar, Yusuf Sadi] AlimexAluminium, Akyazi, Sakarya, Turkey.