On the Issues of Asymmetry Observed in Heat Transfer & Material Flow in Friction Stir Welding

2012 ◽  
Vol 622-623 ◽  
pp. 289-293
Author(s):  
Barnik Saha Roy ◽  
Arnab Samaddar Chaudhuri ◽  
Subhash Chandra Saha

In this paper, a standard CFD code, COMSOL is used to describe the 3-dimensional modeling of friction stir welding using threaded tool and based on fully sticking friction. A standard threaded tool profile is used for the full flow analysis including heat generation and heat flow. Temperature distribution is analyzed for full sticking and sliding condition. The effect of different operating parameters on the temperature distribution was performed.The importance of cell Peclet number is also investigated in the temperature distribution on advancing and retreading side. The results are in reasonable agreement with the predictions.

Author(s):  
Toshiaki Yasui ◽  
Yuki Ogura ◽  
Xu Huilin ◽  
F. Farrah Najwa ◽  
Daichi Sugimoto ◽  
...  

Abstract For the Friction stir welding (FSW) between aluminum and steel is important to fabricate vehicles with light weight and high strength for safety at low cost. For the fabrication of sound weld, it is necessary to control the material flow during FSW. In this study, the material flow during FSW was elucidated by numerical simulation by computational fluid dynamics (CFD) analysis and simulation experiment by transparent Poly-vinyle chloride (PVC) as simulant of aluminum and tracer material. Based on this material flow analysis, several shapes of welding tool were examined for control of material flow during FSW. Scroll shoulder is effective for enhancement of stirring zone by increasing material velocity around the probe. Flute and fine screw probe promote the material flow in depth and horizontal direction. The welding tool with scroll shoulder and flute and fine screw probe achieved sound weld with highest tensile strength of 120.4 MPa.


Author(s):  
M. D. Bindu ◽  
P. S. Tide ◽  
A. B. Bhasi

A three dimensional computational fluid dynamics (CFD) model has been developed to study the effect of tool pin profile on the material flow and temperature development in friction stir welding (FSW) of high specific strength AA 7068 alloy. Numerical simulations were carried out using a RNG k-e turbulence model. Three tool pin profiles, viz. cylindrical, conical and straight cylindrical threaded were considered for the simulation. The temperature distribution and material flow pattern obtained from the simulation were compared for different pin profiles. Simulation results predicted Temperature distribution and material maxing was better in straight cylindrical tapered thread pin welds. Weld joints were fabricated using the straight cylindrical threaded pin with the same parametric combinations as in the simulation. Peak temperature measured in the experiment was less than that obtained by simulation. Hardness measurements taken at different weld regions has showed that about 71% of that of the base metal hardness is obtained with the threaded tool pin. The microstructure study revealed a defect free weld joint. Precipitates distributed in the microstructure indicate sufficient heat input to join the material without dissolving precipitates. The developed numerical model is helpful in optimising FSW process parameters.


2020 ◽  
Author(s):  
Manoj Kumar ◽  
Ramesh Kumar ◽  
Sachin D Kore

Abstract A fully-coupled 3-D model of FSW was developed for 4 mm plates of AA6061-T6 aluminum alloy based on the Finite Volume Method (FVM) in ANSYS Fluent 14.5 software. Two types of the model; one with the tool and another without tool was developed for different tool geometry and analysis was done for temperature distribution in the workpiece as well as in tool using system coupling for first model and workpiece only in later one. A parametric study was performed at different tool rotational speed regarding temperature distribution, and material flow analysis was carried out for all tool geometries at a single rotational speed. The material behaves differently when passes through the different tool and it was affected by thermal history, viscosity and strain rate for particular tool geometry. Temperature-dependent material properties and a user-defined function (UDF) code of viscosity have been incorporated in the model considering the workpiece as a non-Newtonian viscous fluid. A better material mixing observed in case of threaded pin geometry by using a steady-state laminar flow model. All tapered tool geometries were unable to mix material properly just below and around the pin tip due to very low-velocity magnitude in this region, which may lead to a kind of defect. An asymmetric temperature distribution observed in the workpiece and at higher rotational speed peak temperature observed higher in the workpiece, and the flow of heat was more in tool. Validation of the model was done by performing experiments.


2004 ◽  
Vol 824 ◽  
Author(s):  
Therese Källgren ◽  
Lai-Zhe Jin ◽  
Rolf Sandström

AbstractIn an effort to enhance safety for long time disposal of waste nuclear fuel, friction stir welding has been developed as one alternative to seal copper canisters. To avoid the formation of voids and cracks during the welding process, an understanding of the heat and material flow andthereby the evolution of the microstructure, is of great importance. Finite element modelling has been used to simulate the heat and material flow as well as thermal expansion during the friction stir welding process. A model involving heat transfer, material flow, and continuum mechanics has been developed. The steady state solutions have been compared with experimental temperature observations as well as analytical solutions, showing good agreement. Temperature distribution is affected by the welding speed. For a given reference pointperpendicular to the welding direction, a lower welding speed corresponds to a higher peak temperature. The plunging position of welding tool influences the temperature distribution and therefore the displacement distribution of the weldment.


Sign in / Sign up

Export Citation Format

Share Document