Influence of the Geometry of a Similars Specimen on the Parameters of the Dynamics of the Thermal Field in Friction Stir Welding

Abstract

The paper considers two mathematical models of temperature distribution in the process of friction stir welding (FSW) of dissimilars thin-sheet and bulk samples. The model makes it possible to take into account the geometric dimensions of the welded samples, the thermophysical properties and the temperature distribution in the sample-disk and the sample-hemisphere during the transition of the welded material into the superplastic state. The paper presents comparisons of the temperature distribution for disks with a thickness of 2 and 3 mm, a hemisphere. Temperature measurements were carried out at various points of the hemispherical sample and the disk during the FSW process. These models are used to assess the linear velocity of the FSW associated with the thermophysical properties and mass and dimensions of the welded samples. The calculation results are in satisfactory agreement with the experimental data. A decrease in the thickness of the disk specimen leads to an acceleration of heating in the region adjacent to the rotating welding tool during the FSW. A sample 3 mm thick reaches the state of superplasticity within 3 s, and a sample 2 mm thick - within 1.5 s. The linear speed of the FSW decreases from 6.32 mm/s (h = 2 mm) to 1.85 mm/s (h = 3 mm). Comparison of the calculated dynamics of the temperature of a massive hemisphere with thin disks shows that heating to a superplastic state of an element adjacent to the tool occurs almost equally quickly.KeywordsFriction stir weldingMathematical modelingSimilar materialSuperplastic state