Papers by Author: R. Salekrostam

Abstract: The Friction Stir Welding (FSW), a relatively new welding process, was developed in 1991 at the Welding Institute near Cambridge, England. There are two tool speeds to be considered in friction-stir welding; how fast the tool rotates and how quickly it traverses the interface. These two parameters have considerable importance and must be chosen with care to ensure a successful and efficient welding cycle. The relationship between the welding speeds and the heat input during welding is complex. In this paper the friction stir welding (FSW) process of stainless steel alloys has been modeled using a three dimensional finite element method. A coupled thermal viscoplastic model was used for the simulation. Tool speeds and temperature distribution are coupled and solved together using this method. The relationship between the welding speeds and the heat input during welding is obtained by numerical analysis, and the stress contour occurred by temperature field and tool force is surveyed. In addition, the effects of FSW process conditions on heating mainly near the tool pin are investigated in this paper.

Abstract: Compared to the many fusion welding processes that are routinely used for joining stainless steel 316L, the friction stir welding (FSW) process is an emerging solid state joining process in which the material that is being welded does not melt and is being recast. The welding parameters play a major role in deciding the weld quality. In this investigation an attempt has been made to understand the influences of rotational speed and traverse speed of the tool on the microstructure of the friction stir processing zone in stainless steel 316L. Five different tool rotational speeds have been used to fabricate the joints at four different traverse speeds from this investigation which is the optimum for the tool speed and higher or lower amounts of these parameters are not useful for the process.

Abstract: Friction stir processing (FSP) is a solid state process to modify microstructure and mechanical properties of sheet metals and as-cast materials. In this process stirring action of the tool causes the material to intense plastic deformation that yields a dynamical recrystalyzation. In this study the effect of FSP and process parameters on hardness, and microstructure of stainless steel 316L has been investigated. Also by using of FSP, a composite layer of 316L/SiC has been produced. Results show that FSP leads to a finer and homogenized grain structure, as well as increased hardness, strength, toughness, and elongation at failure of the material. The composites produced by FSP have a uniform distribution of SiC particles between the grains of the base metal.