Fiction Stir Welding(FSW) was first developed in 1991 by british company, The Welding Institute(TWI). Unlike conventional fusion welding method, FSW had characteristic of solid phase welding which did not accompany a process of melting and solidification among the general process. FSW is significantly used in general industry especially in Transportation Industry like automobiles, ships, aircraft, railroad cars etc. Recently, the desire to produce material that is environmentally friendly is increasing and so the important task for Transportation Industry and other industries is to produce a light weight material for the people''s consumption. Aluminum alloys are light weight materials with strong intensity, high corrosion resistance and ease of production. Aluminum alloys are currently being used a lot in automotive industry because bonding between different materials is essential. Because of many technical problems, universal fusion welding method is not suitable for aluminum alloy thus, FSW can be an alternative method. Some factors that affect welding performance of FSW include the feed rate, the RPM and the shape of the tool. Welding performance of FSW is determined by the aforementioned conditions. In this country, there are many study of FSW used by same materials. But the study of FSW used by dissimilar materials is not enough.
In this study, a researcher measured the welding characteristics of FSW of dissimilar materials using Digital Image Correlation(DIC). To improve welding performance, a researcher made optimal conditions that affect welding performance of FSW. Digital Image Correlation is one of the optical measurement methods being employed to measure the property of material. It is non-contact measurement system to find displacement and strain compared with deformed image and before image. Digital Image Correlation can easily measure large area(full-field) unlike contact measurement. Its advantage is that strain was measured until 1000% and easily shows displacement and strain in each point to visualize as a map. In this study, Digital Image Correlation have the variable advantage measured displacement and strain of dissimilar of FSW. The results help to improve welding performance by measuring welding characteristic of dissimilar materials.