JOURNAL OF MATERIALS SCIENCE LETTERS 12 (1993) 1335-1336 Microstructural changes associated with vibratory prepared weldments S. P. TEWARI, A. SHANKER Department of Mechanical Engineering, Institute of Technology, Banaras Hindu University, Varanasi 221005, India The solidification of grey cast irol~L [1] under imposed vibration shows a varying microstructure. Kou and Le [2] showed experimentally that under low- frequency vibration there is improvement in the microstructure and mechanical properties of alumi- nium weldments. Researchers [3-6] have proved that solidification of castings under vibratory condi- tions shows a refinement in grain size, metaUo- graphic refinement and reduction in various casting defects. This letter pertains to the microstructure of the weldments prepared under stationary and vibrat- ory conditions. Micrographs show an appreciable improvement in the grain refinement of the weld- ments prepared under vibratory conditions. Two mild steel workpieces were clamped with the help of C-clamps and angle iron pieces on a vibrating table (Fig. 1). The vibrating table rested on shafts which were supported on bearings. This table was rigidly coupled to an electrodynamic vibrator. A three-phase a.c. transformer and futile-coated mild steel electrodes were used for welding. A oscillator/ power amplifier and vibration meter were used for Pick up - C- c~amp Workpieces Base plate Figurei Experimental set-up. Figure2 Micrograph of stationary weldment. 0261-8028 © 1993 Chapman & Hall Figure3 Micrographs of vibratory weldments: (a) frequency 400 Hz and amplitude 5/xm, (b) frequency 200 Hz and amplitude 10/xm, and (c) frequency 80 Hz and amplitude 30/xm. 1335