Mechanism of splitting of a few Fe‐Mn‐Ni‐base alloys subjected to thermo‐mechanical treatment

Splitting or delamination behaviour of four Fe‐Mn‐Ni base alloy compositions subjected to thermo‐mechanical treatments have been investigated. Delamination has been found to occur in tensile as well as charpy‐V specimens of the higher Mn‐containing alloys after ausforming with fracture surfaces parallel to the rolling plane. No splitting or delamination could be observed in the ausformed higher Ni‐alloy. No splitting occurs in all the four alloys after conventional heat treatment. Marforming produces parting of all the four alloys along a surface parallel to the rolling plane. It appears that the ausformed materials split by way of decohesion of grain‐boundaries. A boundary film of austenite or segregation of Mn atoms in the boundaries may be responsible for this. Marforming seems to promote some kind of texture‐banding which ultimately leads to the delamination.