Research of 50Mn2V continuous casting slab transverse cracking during its retarded cooling process

摘要

In this paper, the reason of 50Mn2V transverse cracking is studied by optical metallo-graphic, SEM and in situ analysis system. Results show that the pearlite is surrounded by the net-like pro-eutectoid ferrite which locates at the former austenite grain boundary, the hydrogen content (ca. 2 × 10~(-4) wt%) exceeds the critical solubility in room temperature structure, divers types and sizes inclusions (10-100 μm), plenty of fissures (2-50 μm) and classical cleavage fracture surface are obviously observed, meanwhile, a great degree of elements segregation (P, S, V, Ni, Cr correspond to 1.757,1.674,1.729,1.475,1.195, respectively) and a poorly 0.9283 integral density exist in this blank, high temperature thermoplastic experiment shows the ductility trough existing until the dynamic re-crystallization temperature range. From the above, internal gas pressure should be the dominant factor that leads the transverse embrittlement, while internal stresses, element segregation and defects play an ancillary role.