L. Wei, T. W. Nelson, BRIGHAM YOUNG UNIVERSITY, PROVO, UT
Friction Stir Welded HSLA-65 steel is investigated at four different heat input conditions. The tool rotational speed was varied from 400 to 600rpm and the travel speed ranged from 50.8 to 254 mm/min. The microstructures of various distinct thermal zones are examined by using Orientation Imaging Microscopy (OIM) and Scanning Electron Microscopy (SEM). In the nugget center, finer polygonal ferrite and lath bainite are formed than base material. In advancing side hard zone, obvious Widmanstätten ferrite and bainite are transformed due to severe plastic deformation experiencing. Most grains in that region have {111}<011> dominant orientation. The investigation of microstructures changes with different heat input is also evaluated. Microstructures in FSW weld are highly dependant on peak temperature, cooling rate, extent of plastic deformation obtained from FSW process and dynamic recrystallization involved. The relationship among friction stir weld process parameters, microstructures and heat input conditions is discussed.
Summary: Friction Stir Welded HSLA-65 steel is investigated at four different heat input conditions. The relationship among friction stir weld process parameters, microstructures and heat input conditions is discussed.
