Continuous Annealing Process of TRIP1000 Steel and Its Microstructure and Properties

A series of intercritical annealing and isothermal treatment in bainite region for low carbon Si-Mn experimental steel were carried out.The mechanical properties of experimental steel after heat treatment were tested through the tensile experiment.The change of content of retained austenite after heat treatment was detected using the analytical method of X-ray diffraction.And the microstructure after heat treatment was observed by SEM.The results show that when intercritical annealing temperature is 820 ℃,isothermal bainite treatment temperature is 420 ℃ and isothermal treatment time is 240 s,the microstructure of three phase,which are ferrite,bainite and retained austenite,can be obtained in TRIP1000.Under this heat treatment process,crystal dimension of the specimen is between 2 μm and 4 μm,the content of retained austenite in the specimen and the content of carbon in retained austenite are higher than other specimens'.So TRIP1000 steel has the best mechanical properties,and its UTS×EL can reach 23088MPa.%.