# A Literature Survey on Electrical-Current-Assisted Friction Stir Welding
## 4 Various Types of EA-FSW Tools
The various joints and related data collected from dissimilar EA-FSW joints are presented in Table 2. Due to limited data about EA-FSW joints between dissimilar materials, it can be seen that the rotational tool speed is much higher than the EA-FSW of similar joints. This is due to the second alloy's higher melting point and strength than the first one. The range of electrical current used is related to the base materials. The typical current used for a similar joint was below 720 A, while the electrical current used in a dissimilar joint reached 1000 A. On the other hand, the tools with Type a and Type c were used in dissimilar joints. The current and tool rotational velocity can determine the soundness of final joints. The typical tool material used for dissimilar EA-FSW was tool steel. The ceramic composite material introduced as the XYTIN-1 alloy was the specific material used for an EA-FSW \begin{table}
\begin{tabular}{c c c c c} \hline
**Tool Material** & **Type of Tool** & **Electrical Current** & **Rotational Velocity** & **Workpiece** & **Ref.** \\ \hline H-13 tool steel & Type a & Not mentioned & 555 rpm & AA6061-T6511 aluminum & [26] \\ \hline A2 tool steel & Type a & 37.2 A & 350 rpm & AA6061 aluminum & [27] \\ \hline Not mentioned & Type c & 720 A & 1120 rpm & AA6082-T6 aluminum & [28] \\ \hline H13 tool steel & Type b & 720 A & 1120 rpm & AA6082-T6 aluminum & [29] \\ \hline Not mentioned & Type d & 0–600 A & 800 rpm & AA2219-T87 aluminum & [30] \\ \hline T12 carbon tool steel & Type c & 0–150 A & 940 rpm & AA7075 aluminum & [31] \\ \hline T12 carbon tool steel & Type c & 0–150 A & 1000 rpm & AZ31B Magnesium & [31] \\ \hline H13 tool steel & Type a & 0–400 A & 800 rpm & AZ31B Magnesium & [32] \\ \hline Not mentioned & Type a & 0–200 A & 1300 rpm & AZ31B Magnesium & [33] \\ \hline Tungsten rhenium & Type d & 100–300 A & 200 rpm & Ti-6 Al-4V Titanium & [34] \\ \hline Tungsten rhenium & Type d & 100–300 A & 200 rpm & Ti-6 Al-4V Titanium & [35] \\ \hline Tungsten Carbide & Type a & 50–150 A & 500, 700 and 1000 rpm & Low carbon steel & [36; 37; 38] \\ \hline Tungsten Carbide & Type a & 50–150 A & 600, 800 and 1000 rpm & Inconel 601 & [39] \\ \hline \end{tabular}
\end{table} 
Table 1: Used tools and process parameters in EA-FSW of similar joints. \begin{table}
\begin{tabular}{c c c c c} \hline
**Tool Material** & **Type of Tool** & **Electrical Current** & **Rotational Velocity** & **Workpiece** & **Ref.** \\ \hline Not mentioned & Type c & 0–500 A & 800–1500 rpm & AA6061 aluminum to AZ31B magnesium & [31] \\ \hline T12 carbon tool steel & Type c & 1000 A & 1000 rpm & 2 Cr13 Mn9 Ni4 stainless steel to & [40] \\ \hline XYTIN-1 & Type a & 10 A & 1800 rpm & AA6061-T6511 aluminum to & [41] \\ \hline H13 tool steel & Type a & 560 A & 2000 rpm & AA6061-T6 aluminum to TRIP steel & [42] \\ \hline H13 tool steel & Type a & Not mentioned & Not mentioned & 7075-T6 aluminum to glass & [43] \\ \hline Tungsten & Type a & 400 mA & 1200 rpm & high-density polyethylene (HDPE) to 316L stainless-steel textile & [44] \\ \hline \end{tabular}
\end{table} 
Table 2: Used tools and process parameters in EA-FSW of dissimilar joints. tool when joining aluminum to steel. By comparing the data, any relation between tool material and used electrical current or rotational velocity cannot be found. The collected data indicate that the lowest electrical current (37.2 A) was used with the A2 tool steel during the joining of AA6061 aluminum alloy, and the highest electrical current (1000 A) was used for dissimilar EA-FSW during the joining of 2 Cr13 Mn9 Ni4 stainless steel to Q235B steel. The harder materials need a higher electrical current to become soft, and softer materials need a lower electrical current. During EA-FSW, the researchers selected the joint type of the tool type related to the final properties of the joint. By selecting various joint types, the joint line can be affected by electrical current. During the welding procedure, the joint line can be affected by external heat.