Study of sub-shoulder tool wear on friction stir welded steel plates using two modes of metal transfer phenomenon.

Tool wear study is undertaken with IS 3039, grade II steel plates and analysed by two modes of the metal transfer phenomenon. The first mode of metal transfer takes place by the direct contact of the tool shoulder on the work plate, generating heat owing to friction, and the second mode of metal transfer takes place around the pin. This study is aimed at knowing the formation of a weld for every 300-mm length, which indirectly reflects the effect of the pin profiles on producing a better weld. The individual contribution of two modes of metal transfer has been studied, and it was observed that the higher the area of the first mode of metal transfer, the more the strength of the weld. The variations in the distribution of hardness along the first mode of metal transfer were found to be higher, because the compaction offered by the tool shoulder is more than that in the second mode of metal transfer. Microstructure and macrostructural analyses were performed on the weld, based on the two modes of the metal transfer phenomenon. The ultimate tensile strength gets reduced, if the percentage formation of the first mode of metal transfer is less. [ABSTRACT FROM AUTHOR]