# Comparison of Two Intergranular Corrosion Tests on EN AW-6016 Sheet Material
## 2 Experiment  
Sheet material made of EN AW-6016 with a thickness of 1 mm was cut into rectangular pieces with a size of 50 \(\times\) 30 mm\({}^{2}\). Two different IGC tests were carried out on eight such samples. Six pieces were tested with modified versions of the ISO 11846:1995 [18]. The basic testing procedure without modifications is shown in Table 2. The other two pieces were tested following the VW-Audi PV1113 testing procedure [16]. This procedure is also shown in Table 2. The cleaning of the PV1113 samples in this work was done with acetone.  
The modifications to the ISO 11846:1995 were proposed by the German \"Gesamtverband der Aluminiumindustrie e.V.\" (GDA, General Association of the Aluminum Industry)  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**EN AW-6016** & **Al** & **Fe** & **Si** & **Mn** & **Cr** & **Ti** & **Cu** & **Mg** & **Zn** \\ \hline
**Min (wt.\%)** & Bal. & — & 1 & — & — & — & — & 0.25 & — \\
**Max (wt.\%)** & Bal. & 0.5 & 1.5 & 0.2 & 0.1 & 0.15 & 0.2 & 0.6 & 0.2 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Composition limits of EN AW-6016 [11].  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Method** & **Sample Preparation** & **Pre-Cleaning** & **Test Solution** & **Solution** & **Exposure Time** & **Reference** \\ \hline
**ISO 11846:1995** & 50 \(\times\) 30 mm\({}^{2}\) & \begin{tabular}{c} Degreasing with acetone, 5\% \\ NaOH solution for 1 min at \\ 60 \({}^{\circ}\)C, 70\% HNO3 for 1 min, \\ rolling direction \\ \end{tabular} & \
\begin{tabular}{c} Degreasing with acetone, 5\% \\ NaOH solution for 1 min at \\ 60 \({}^{\circ}\)C, 70\% HNO3 for 1 min, \\ cleaning with acetone and \\ DI water \\ \end{tabular} &
\begin{tabular}{c} Degreasing with acetone, 5\% \\ 100 00 mL H\({}_{2}\)O, \\ 30 g NaCl, 10 mL \\ 37\% HCl \\ \end{tabular} & Not defined & 24 \(\pm\) 0.25 h at 30 \(\pm\) 0.2 \({}^{\circ}\)C & [18] \\ \hline
**PV113** & Sample size & \
\begin{tabular}{c} Mandatory grinding of the \\ edges with 120 grinding \\ paper, degreasing with \\ acetone or paraffin oil, \\ ultrasonic cleaning \\ in alcohol \\ \end{tabular} &
\begin{tabular}{c} 1000 mL H\({}_{2}\)O, \\ 20 g NaCl, \\ 100 mL 25\% HCl \\ \end{tabular} & Min. 8 & 2 \(\pm\) 0.5 h at room  temperature & [16] \\ \hline \hline \end{tabular}
\end{table}
Table 2: ISO 11846:1995 and PV113 testing method parameters.  
in order to better compare test results in a round robin IGC test. It includes two different solution amounts and three different acid concentrations as shown in Table 3. ISO 11846:1995 usually demands testing three samples for better statistics. In this work, only one sample per 11846:1995 variant (Table 3) was tested. The time tolerances shown in Table 2 were kept to a minimum of less than two minutes to allow better comparability of the two different test methods and the varying testing parameters of ISO 11846:1995.  
After cleaning, the samples were polished and optically investigated with a Zeiss Imager.A2m optical microscope (OM). The highest IGC depth was averaged over three different areas of each sample with a magnification of 100. This results in eight IGC depths (6 for ISO 11846:1995-based and 2 for PV1113).