Achieving the Dual Phase Structure in Low Alloyed Steel with Slow Cooling Rate
In steel wire processing it is difficult to reach a homogenous structure throughout the cross-section of the wire particularly in greater diameters. One alternative for producing a homogenous structure is to find a cooling path with a wide transformation temperature range. Fully austenite steel wire rolled at high temperatures can be decomposed into ferritic-martensitic dual phase structure using relatively slow cooling rates. Test materials were low alloyed low carbon steels with variations in alloying elements. Gleeble-1500 thermomechanical simulator was utilised to study the effect of cooling rate on decomposition of austenite after deformation. The microstructures were studied with an optical microscope. In certain low alloyed steels slow cooling rates eliminate the bainite transformation and instead martensite is formed. The final microstructure depends mainly on the carbon content but also on the amount of other alloying elements and their effects on the austenite phase.
Jitai NIU, Zuyan LIU, Cheng JIN and Guangtao Zhou
T. Jäppinen and S. Kivivuori, "Achieving the Dual Phase Structure in Low Alloyed Steel with Slow Cooling Rate", Materials Science Forum, Vols. 575-578, pp. 1117-1122, 2008