Friction Stir Welding Temperature Field Experimental Research Of Aluminum Alloy

At present, most of the experimental studies on friction stir welding are measure thedistribution of temperature field by using thermocouples. But the systematic studies aboutthe temperature distribution of the friction stir tool are very few. Get the temperature field ofthe tool is important to guild the simulation of the boundary factors during the friction stirwelding process.The problem is how to measure the temperature field when the tool is in thehigh-speed rotating. In this paper, based on previous designing,the temperaturemeasurement system of friction stir tool is improved and calibrated.The experimental dataof the temperature measurement system are more accuracy and reliability.Various type of friction stir tools were designed. The temperature field of the tools andworkpieces with different material, different geometric feature of tools and different coolingcondition during the friction stir welding process is systematically studied by using the tooltemperature measurement system and the workpieces temperature recorder. The impact ofthe various boundary conditions on the temperature distribution of the tools and workpieceis analyzed. The similarities and differences of the test panels temperature curve withdifferent materials are preliminary explored.Results indicated that the temperature curves of tools and workpieces have a apparentlystage regularity. A smaller heat capacity could lead to the decrease of temperature and theincrease of the temperature change rate. More nearly corresponding to the feature points ofthe test workpiece joint line, the temperature difference is more obvious. With the samediameter,the temperature is lowest in the case of conical pin while the highest in the case ofcylindrical pin. With the same distance to the shoulder of friction surface, the temperature ofthe away from the axis point is higher than the point which near the axis. But to the point atthe edge of the tools, the temperature in the process of friction stir welding need to considerthe convective heat transfer factor with the air.Regression analyses by the least squaresmethod are used to predict the temperatures at the joint line. A second-order polynomialcurve is found to best fit the experimental temperature values in the width direction of theworkpiece.