Investigation on cracking mechanism of austenite stainless steel during in situ tension in transmission electron microscope

Twin-roll strip casting technology is a new one to produce austenite stainless steel strip directly. However, during this process, the cracking occurs usually on the surface of the steel strip. The technique of in situ tension in transmission electron microscope was used to observe and analyze the crack initiation and propagation in austenite stainless steel produced by twin-roll strip casting technology in this work. The results show that the crack initiates in dislocation free-zone firstly and then propagates along the direction vertical to the tensile force. The crack may propagate in continuous propagation way and discontinuous one respectively. When the shear stress on the close-packing face and the normal stress on the secondary close-packing face are at the same side of the tensile force, the cracks propagate continuously. However, when the shear stress on the close-packing face and the normal stress on the secondary close-packing face are in two sides, the cracks propagate discontinuously.