6.5 Material testing
The quality of the welds and the sheet material also needed to be assessed independently. Samples from both intact and cracked welds were sectioned, and the sections polished and etched to show any internal structure. No serious problem with weld structure could be found (Figure 8, Paper 4). The tensile strength of the welds also proved reasonably consistent with one another and the manufacturer's figures (Table 1, Paper 4). Chemical analysis of the weld and bulk materials using DSC proved negative, the melting points all being close to one another. FTIR showed no obvious anomalies, such as an oxidation peak.