Aluminum alloy 6063-T5 and AISI SAE 1020 were obtained with dissimilar welded joints by friction stir welding in 2.0 mm thick sheet. The aim was to evaluate the effect of welding parameters to obtain Al-steel welds. Joints were evaluated according to surface quality and depth of the welded region. It was determined that besides the rotational (ω) and forward (υ) speeds, the offset and the tool penetration are key parameters because they define the heat input and therefore the adherence of aluminum in the tool, the surface quality and defect formation along the joint line.163265273Agudo, L., Intermetallic FexAly-phases in a steel/Al- alloy fusion weld (2007) Journal of Materials Science and Engineering, 42, pp. 4205-4214. , DOI 10.1007/s10853-006-0644-0Watanabe, T., Joining of aluminum alloy to steel by friction stir welding (2006) Journal of Materials Processing Technology, 178, pp. 342-349Chen, C.M., Kovacevic, R., Joining of Al 6061 alloy to AISI 1018 steel by combined effects of fusion and solid state welding (2004) International Journal of Machine Tools and Manufacture, 44, pp. 1205-1214Jiang, W.H., Kovacevic, R., Feasibility study of friction stir welding of 6061-T6 aluminium alloy with AISI 1018 steel (2004) Proceedings of the Institution of Mechanical Engineers, 218, pp. 1323-1331Fukumoto, M., (2004) Proceedings of the Fifth International Friction Stir Welding Symposium, , FranceUzun, H., Friction stir welding of dissimilar Al 6013- T4 to X5CrNi18-10 stainless steel (2005) Materials and Design, 26, pp. 41-46Lee, W., (2006) Interfacial Reaction In Steel-aluminum Joints Made By Friction Stir Welding, 55, pp. 355-358. , Scripta MaterialiaChen, T.J., Process parameters study on FSW joint of dissimilar metals for aluminium-steel (2009) Journal of Materials Science, 44, pp. 2573-2580Chen, T.P., Lin, W.-B., Optimal FSW process parameters for interface and welded zone toughness of dissimilar aluminum- steel joint (2010) Science and Technology of Welding and Joining, 15 (4), pp. 279-285Yasui, T., (2004) Proceedings of the Fifth International Friction Stir Welding Symposium, , FranceTanaka, T., Comprehensive Analysis of Joint Strength For Dissimilar Friction Stir Welds of Mild Steel to Aluminum Alloys, , Scripta Materialia, doi:10.1016/j.scriptamat.2009.06.022Soundararajan, V., Kovacevic, R., (2006) Proceedings of the Sixth International Symposium On Friction Stir Welding, , Quebec, CanadaCoelho, R.S., Microstructure and Mechanical Properties of an AA6181-T4 Aluminium Alloy to HC340LA High Strength Steel Friction Stir OverlapWeld (2008) Advanced Engineering Materials, 10 (10), pp. 961-972Coelho, R.S., EBSD Technique Visualization of Material Flow in Aluminum to Steel Friction-Stir DissimilarWelding (2008) Advanced Engineering Materials, 10 (12), pp. 1127-1133Totten, G.E., Mackenzi, D.S., (2003) Handbook of Aluminum: Physical Metallurgy and Processes, 1. , Marcel Dekker, Inc, New York, USABourget, J.-P., Optimization of heat treatment in cold-drawn 6063 aluminium tubes (2009) Journal of Materials Processing Technology, 209, pp. 5035-5041Zhang, J., Equilibrium pseudobinary Al-Mg2Si phase diagram (2001) Materials Science and Technology, 17, pp. 494-496Heinz, B., Characterization of a Friction-Stir- Welded Aluminum Alloy 6013 (2002) Metallurgical and Materials Transactions B, 33, pp. 489-498Gavgali, M., The effects of artificial aging on wear properties of AA 6063 alloy (2003) Materials Letters, 57, pp. 3713-3721Al-Marahleh, G., Effect of heat treatment on the distribution and volume Fraction of Mg2Si in structural aluminum alloy 6063 (2006) Metal Science and Heat Treatment, 48 (5-6), pp. 205-209Yang, Y.K., Liquation of Mg alloys in friction stir spot welding (2008) Welding Journal, 87 (7), pp. 167s-177s