Toughening mechanism of inter-critical heat-affected zone in a 690 MPa grade rack plate steel

摘要: Abstract The inter-critical heat-affected zone (ICHAZ) and fine grain (FGHAZ) of a 690 MPa grade rack plate steel were simulated by Gleeble3500 simulator. toughening mechanism ICHAZ was clarified analyzing microstructural characteristics instrumental Charpy impact tests. study showed that the had higher toughness than FGHAZ. And microstructure in FGHAZ martensite, while bainitic obtained ICHAZ. Both prior austenite size effective smaller FGHAZ, which played an important role improving It found extensive plastic deformation fracture could consume large energy during crack initiation propagation. capacity related to fraction large-angle boundaries low dislocation density, as well homogeneous distribution local strain geometrically necessary dislocations.