Microstructures and Tensile Properties of Friction Stir Welded 0.2%C-2%Si-Cr Steels

The 0.2C-2Si (mass%) steels with the addition of 0–4 mass% Cr were prepared by hot rolling followed subsequent annealing for normalization. subjected to friction stir welding (FSW) conducted above A3 temperature. For all steels, sound FSWed joints obtained. Microstructures and tensile properties using small specimens investigated both base materials zones. showed a relatively good balance strength ductility when content is over 3 presumably owing fine microstructures ferrite martensite. zones substantially enhanced FSW, zone 0.2C-2Si-4Cr joint fully martensitic structure exhibited surprisingly high 1720 MPa compared that conventional steel 0.2 mass%C together excellent ductility. This assumed be caused refinement block size in fresh lath martensite and/or formation ausformed induced dynamically recrystallized austenite grains FSW added steels.