الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 88 |  |  |
| | | from | 88 | | |
Abstract
The aim of this research is to study the effect of post weld heat-treatment (PWHT) and different process parameters on friction stir spot welding (FSSW). The quality characteristics chosen were categorized into mechanical properties and microstructure. A Taguchi based plan orthogonal array L27 were used for the acquisition of data. Signal-to-noise ratio (S/N) and analysis of variance (ANOVA) are used to optimize welding parameters. The parameters which have the most effect and the optimum combination of welding parameters levels were gained through the response graphs of ANOVA and S/N ratios. The results revealed that the most affecting welding parameter for the shear load of the weld and micro-hardness was PWHT, while the dwell time was the parameter that followed. For both microhardness and shear load, the combination of welding parameters levels 1500 rpm, 10 sec and T4 were the optimum. The improvement of grain size were obtained when reduce dwell time and/or reduce tool rotational speed and also when heat-treatment of welded joints. The combination of welding parameters levels 1200 rpm, 6 sec and T4 were the optimum to get minimum grain size.