Evaluation of Flash Bainite in 4130 Steel

ARDEC independently evaluated a Flash Bainite process developed by Gary Cola, Jr., Sirius Protection LLC. Chemical analysis, welding including flash processing after welding, bend, tensile, fracture toughness, x-ray diffraction, impact toughness, and Gleeble heat affected zone tests were performed on AISI 4130 steel plate. When possible, testing was baselined against conventional quench and tempered material. Manufacturability tests demonstrated that Flash Bainite plate is weldable and bendable, and that welded plate can subsequently be flash processed to restore strength. Small tensile residual stresses were measured in the welded plate and approximately two percent retained austenite was measured in the base material. Flash Bainite demonstrated an impressive combination of strength, elongation, ductility and toughness. Moreover, its impact toughness was consistently higher than quench and tempered plate at all test temperatures evaluated. Intergranular cracking was observed on the fracture surface of some the Flash Bainite impact toughness specimens. The impact toughness testing on the Gleeble heat affected zone specimens in the Flash Bainite and quench and tempered conditions exhibited equivalent results. Though this subject testing identified a few issues that need to be addressed, the Flash Bainite processing of 4130 steel demonstrates promise for applications needing a combination of high strength with good elongation, ductility, and toughness e.g. armor and vehicle. The novel Flash Bainite process for steels has the potential to reduce product cost and weight while also enhancing mechanical performance.