On friction stir butt welding of Al+12Si/10 wt%TiC in situ composite

The stirring action and solid state nature of friction stir welding process provide interesting possibilities for very fine refinement and redistribution of in situ reinforcements in the grain refined metal matrix. The present investigation discusses the effect of varying process parameters on friction stirred butt welded hot rolled Al + 12%Si/10 wt%TiC in situ composites. A bimetallic tool with flame hardened titanium alloy probe was used in the experiment. The tool shoulder dimension, welding speed and tool rotational speed were varied during welding to study their effects on the ultimate tensile strength, percentage elongation and micro-hardness of the butt joints. Plan of full factorial design was followed for producing the Al + 12%Si/10 wt%TiC butt welds. The friction stirred weld zone of the aforementioned composite exhibited grain refinement of the matrix as well as refinement and uniform redistribution of in situ reinforcements. The average value of the micro-hardness in the weld zone varied significantly with respect to the process parameters and tool design. The ultimate tensile strength of the weld joints also varied from 124.23 MPa to 171.74 MPa based on the process parameters and tool type. The desired outputs were also optimized as per the multi-response desirability function-based technique. The observed 0.07-2.98% error in the optimality test results witnessed the adequacy of the adopted optimization technique. (C) 2013 Elsevier Ltd. All rights reserved.