Hot-rolled Steel Sheet Of Carbon Ultrafine Grain Microstructure And Mechanical Properties

In order to research the microstructures and mechanical properties of hot rolling sheets with ultra-fine grain,influence of deformation temperature on austenite recrystallization grain size are studied through adopt GLEEBLE hot simulate test method.Influence of coiling technology on ferrite grain fine and regular of deformation induce ferrite transformation in hot rooling are also studied.Influence of finish rooling temperature and coiling temperature and deformation value and steel base gauge on microstructures and mechanical properties of plain carbon hot rolling steel sheets are investigated through laboratory rolling test.The ultra-fine grain hot rolling sheets are produced with plain carbon composition in Pansteel 1450 industrial mill through control whole technological process of heating,finish rooling and coooling.The microstructure and mechanical properties and forming properties and corrosiveness-resistant of ultra-fine grain hot rolling steel sheets of industry produce are researched.The auto parts which made with ultra-fine grain hot rolling sheets are analysed.The paper are summarized as the following:The influence of deformation temperature on recrystallization austenite grain size are studied.The results show that recrystallization austenite grain size are fined remarkably with the drop of deformation temperature.Dropping rolling temperature are effective on fining original austenite grain size.Lower deformation temperature and lower deformation value are beneficial to deformation induce ferrite transformation.The finer recrystallization microstructure are obtaind in higher strain rate.The austenite stability are cut down by fined austenite.The deformation induce ferrite transformation can be taken place through rolling deform of roughing and finish rolling leads to finer original austenite grain size and dropping finish temperature in reality rolling plain carbon steel,accelerated cooling after finishing rolling to suppress the grain growth are needed.With the drop of coiling temperature,the ferrite grain size tends to be finer.The ultra-fine grain hot rolling steel sheets with Q235 plain carbon are produced in Pansteel 1450 industrial mill through adopting a series of technology measure with heating,rough rolling,finish rolling and cooling.Microstructure of ultra-fine grain hot rolling steel sheets are ferrite and pearlite.The ferrite proportion are about 80%～85%and pearlite proportion are about 15%～20%in microstructure.The yield strength is over 400MPa,the tensile strength is over 510MPa,the steel sheets have higher plasticity and toughness.The plain carbon hot rolling steel sheets with ultra-fine grain have excellent cold bending properties and impact properties,higher corrosiveness-resistant and forming properties.The hot rolling steel sheets have excellent comprehensive properties.