There are many industrial applications where different types of materials must be combined and used. However, this is not always possible with welding, bonding and other disassembling methods or it contains various problems. In order to eliminate these problems, mechanical locking method (MLM), which is a new and environmentally friendly method, is used as an alternative to classical joining methods. MLM method can be used especially in joining material pairs with different chemical and physical properties.However, it can be preferred in situations where it is desired to reduce microstructure defects caused by high heat input. In this study; For MLM method, the effect of the connection angle, which can directly affect the joining quality, on the microstructure and mechanical properties was investigated. For this purpose, AISI 1040 steel and AA6013 aluminum alloy were joined at different connection angles (7°, 10° and 13°) using the MLM method. After the joining process, microstructure analysis, microhardness measurements and tensile tests were performed and the connection performance was determined. At the end of the study, the highest mechanical properties were obtained with a value of 241.38 MPa in the samples prepared with 13° connection angle. An other samples where the connection angle was lower, it was determined that the flange formation performing the connection showed an irregular distribution, the material flow was insufficient and the mechanical properties decreased as a result.