Effect Of Process Conditions On Microstructure And Properties Of Fe-based Nano-alloys

The development of global economy has put forward higher requirements for steel materials,so the research on the hot rolling process of medium carbon steel is beneficial to obtain good and cheap materials.Microstructure and properties of medium carbon pseudoeutectoid steel were studied by means of SEM,EBSD and tensile test.By rolling the medium carbon pseudoeutectoid steel at different temperatures of500 °C,550 °C,600 °C,650 °C and 700 °C,it is found that as the rolling temperature increases,the degree of cementite fragmentation increases.The average grain size of ferrite increases,the tensile strength decreases,and the total elongation gradually increases to constant.After rolling at 500 °C,the average grain size of ferrite is the smallest,which is 374 nm.The tensile strength after rolling at 550 °C is 1228 MPa,the total elongation is 6.8%,and the comprehensive mechanical properties are the best.The medium carbon pseudoeutectoid steel rolled at 500 ℃ was annealed at 600 ℃for 10 min,15 min,30 min and 60 min respectively.The distribution tends to be uniform,the tensile strength increases and then decreases,and the total elongation increases.As the rolling temperature increases,the distribution of spherical cementite in the annealed structure becomes uniform and the size increases.After annealing,the experimental results show that the tensile strength of medium carbon pseudoeutectoid steel rolling at550 °C and annealing at 600 °C for 30 min is 785 MPa,the total elongation is 9.5%,and the comprehensive mechanical properties are the best.The medium carbon pseudoeutectoid steels with different pro-eutectoid ferrite contents were rolled at 500 ℃ and annealed at 600 ℃ for 30 min showed that the smaller the proeutectoid ferrite content is,the smaller the average grain size of ferrite after warm rolling is,the higher the tensile strength is,and the greater the uniform elongation is.The smaller the average grain size of ferrite after annealing,the higher the tensile strength and the smaller the uniform elongation.Figure 42;Table 6;Reference 71...