The paper describes the substance-to-substance joining of the material combination CrNi steel and AlMg alloy. The joint was created through a thermal joining procedure in the solid state without interlayers. Material characteristics such as thermal strain and hardness were investigated. The investigations were conducted in the transition areas of the joining zones depending on the joining parameters. The joining quality of the surfaces was especially assessed and the diffusion zones were classified by means of the scanning electron microscope. Crack-free and homogeneous joining zones, which guarantee a high-quality joint with adequate strength, were the primary objective of the investigations.