EN-GJMW-400-5 | Annealing A

The photos illustrate a white malleable cast iron after a short-day annealing. In the edge zone up to 100 µm there is a slight grain boundary oxidation. This is followed by the decarburised, completely ferritic zone. The areas where the annealed carbon was located are empty (hollow).
In thicker cross-sections, the ferritic zone is followed by a transition zone in which ferrite and pearlite are present. Even in the pearlitic zone near the edge, there are cavities from the former annealed coal. In the core there is still annealed coal, which is only completely removed by the second annealing.

The SEM images show a violent fracture caused by tensile testing. The remaining cavities of the former malleable coal can be seen impressively. Honeycomb fracture is present in the decarburised edge area and transcrystalline, brittle forced fracture in the core cross-section.