Welcome to the LeTourneau University Friction Stir Welding Senior Design Project web page. This site will give you an overview of what we’re aiming to accomplish this academic year. Below is a summary of the process characteristics and what makes Friction Stir Welding unique when compared to other joining methods. If you have any questions pertaining to the information on this web site, please contact us by following the contact link on the left.
Friction Stir Welding (FSW) was introduced in
1991 by The Welding Institute as a new method for joining materials. It presented a revolutionary method of joining dissimilar and previously un-weldable materials through solid-state bonding. The advantage of this is that no melting is involved during welding, which eliminates the many problems associated with solidification. Many materials lose strength due to the undesirable microstructure produced by melting and solidification. This is one of the main problems that we are trying to correct. FSW uses a rotating tool to ‘mix’ the solid metal together, creating a metallurgical bond. In our particular case, the U.S. Transportation Dept. is looking for an effective way to join High Performance Steel (HPS) 70 and A1010 stainless steel. The FSW eliminates the negative effects of fusion welding process by preserving the microstructure which leads to sustained performance. Pictured above is the current machine we're using to complete our project. It is shown welding on Aluminum.
It is very difficult to friction stir weld A1010 stainless steel or HPS 70W due to its high strength and high heat input demands for sufficient plasticization. The aim of our senior design project is to successfully weld A1010 stainless steel by making a hybrid weld process combining FSW and High Frequency Induction (HFI) welding.
The goal of this new hybrid process is to force the heating to be extremely localized through HFI and also gain a favorable microstructure through FSW. The HFI heating should significantly cut down on the frictional heating demands from the tool bit. The shoulder and pin are subjected to the highest heat and frictional wear, thus limiting the overall tool life. Currently, the initial plunge and the amount of frictional heating required of the tool bit is the major cause of tool life reduction. The reduced demands on the tool will hopefully extend its life and increase travel speeds, making this process more lucrative for companies who can benefit from the improved microstructure properties. Pictured to the left is the current tool design equipped with a replaceable tip insert. The insert, composed of the shoulder and pin, will wear out, but when it does, only the tip needs to be replaced instead of the entire tool.