Effect of welding parameters on microstructure and mechanical properties of friction stir welded plain carbon steel

Abstract

In the present investigation, friction stir welding was carried out for plain carbon steel under variable rotational and traversing speed of tool keeping all other welding parameters same. Microstructural characterization was carried out for welded samples along with determination of microhardness distribution and evaluation of mechanical properties. Weld nugget microstructure principally consisted of ferrite-pearlite, however ferrite grain size and pearlite area fraction were varied depending on welding parameters. Substantial grain growth was found in heat affected zone. Sub-size tensile specimens exhibited improvement in strength; whereas, standard tensile samples showed lowering in strength with respect to parent alloy. Ductility of subsize and standard specimens showed smaller value in comparison to parent alloy and dependent on local microstructural characteristics. © 2012 ISIJ.