The Effect of Friction Stir Processing Speed Ratio on the Microstructure and Mechanical Properties of A 430 Ferritic Stainless Steel

This study is an attempt to investigate the effect of welding rotational and traverse speed on mechanical and microstructural properties of A 430 stainless steel in order to give an effective processing window to achieve an appropriate microstructure and so mechanical properties. There are a wide range industrial uses for ferritic stainless steel. There from they have some problems like grain coarsening and martensitic transformation during conventional fusion welding, solid state welding methods has found a great interest. A heavy duty NC machine is used for FSW. Water cooled brass chamber is used to prevent the tool from severe wear and damage. In order to study the effect of rotational to welding speed ratio ( ) on microstructure, rotational speeds of 600, 800 rpm and welding speeds of 50, 100, 150, 200 mm/min with a spindle tilt angle of 3° are selected. Results showed that ferrite grain size decreased by increasing welding speed at constant rotational speeds which prove dynamic recrystallization occurrence in the nugget zone. Mechanical tests showed that strength and hardness of weld zone in increased compared to base metal.