The alloys 1.7386, 1.4841, 1.4959 and 2.4816 were tested under conditions simulating a thermal cracking process. Tests were performed at 480, 580 and
680 °C, for 24, 72 and 240 h in a gas atmosphere containing 3.8 vol.% HCl, 200 ppm H2S and CO, CO2 and N2. It represents the partial pressures, which are present in the reactor of a thermal cracking process of anthropogenic resources. The software FactSage 7.0 and PetroSIM were used to calculate the composition of the artificial gas mixture.

Flat samples were prepared from pipes and showed the dimensions of 25x10x2 mm. In order to achieve a uniform surface the samples were ground to 1000 grit SiC paper. After corrosion experiments the samples were analyzed by metallography, SEM/EDX and XRD. Additionally the mass loss of the samples during the experiment was evaluated.

After the tests the samples showed a multilayered surface structure. The outer layer consisted mainly of chromium sulphide, followed by a chromium oxide layer. Below these two layers a chlorine containing layer was detected. This general structure of corrosion products was detected at all tested materials. The FeCl2 was not observed on the samples, but as colorless crystals at the colder parts of the testing equipment.

At high testing temperatures the mass loss decreased with increasing nickel content. However, at lower testing temperatures this effect changed entirely, so that at 480 °C 1.7386 and 2.4816 showed nearly the same mass losses.