In this study, the effect of preheating on the quality of the joint created by simultaneous friction drilling of aluminum alloy AA6061T6 and stainless steel AISI304L sheets was experimentally investigated. Preheating temperatures of 250 , 300, and 350 °C were applied to the components, and the resulting joints were compared to those formed at ambient temperature (39 °C). The tensile test results indicated a reduction of 13% to 32% in the joint failure threshold in preheated specimens compared to specimens produced by friction drilling at ambient temperature. It was also observed from the results of hardness test that all three preheated samples have lower hardness than the sample produced by friction drilling at ambient temperature. Moreover, preheating the samples up to 350 °C improves the formability of aluminum sheets and eliminates the cracks in the joint area due to the reduction in hardness and microstructural changes in the joint. However, preheating at temperatures below 350 °C does not yield favorable results as it fails to prevent the crack formation and reduce the distance between the sheets near the joint.
