The composition,morphology,size,and number of inclusions in Fe-22Mn-xAl-0.7C(x=0.5%,5.2%,and 10.5%)lightweight steels after smelting and heat treatment experiments are characterized by scanning electron microscopy and...The composition,morphology,size,and number of inclusions in Fe-22Mn-xAl-0.7C(x=0.5%,5.2%,and 10.5%)lightweight steels after smelting and heat treatment experiments are characterized by scanning electron microscopy and energy-dispersive X-ray spectroscopy from both 2D and 3D perspectives.The inclusions are classified into eight categories according to chemistry and morphology.For the steel sample with a low Al content(0.5%),the inclusions are MnS,AlN-MnS,and Al_(2)O_(3)-MnS,among which Al_(2)O_(3)-MnS is the primary type.With the increase in Al content in the steel sample(to 5.2%),the populations of AlN and AlN-MnS inclusions of 1-3μm in diameter increase.A further increase in Al content(to 10.5%)leads to a significant decrease in the amount of AlN inclusions of 1-3μm in diameter,and an increase in the amount of AlN-MnS inclusions.The precipitation behavior during the phase transformation is also studied by FactSage 8.0 thermodynamic software,and a precipitation mechanism is proposed based on the calculation results.During the heat treatment,AlN inclusions re-precipitate out,due to the interactions between Al and dissolved N in the steel matrix.However,AlN inclusions cannot grow large because of unfavorable kinetic conditions.The re-precipitation phenomenon of AlN is predominant under low Al and high N conditions but not at high Al cases.展开更多
基金This work was supported by the National Natural Science Foundation of China(Grant No.U20A20270).
文摘The composition,morphology,size,and number of inclusions in Fe-22Mn-xAl-0.7C(x=0.5%,5.2%,and 10.5%)lightweight steels after smelting and heat treatment experiments are characterized by scanning electron microscopy and energy-dispersive X-ray spectroscopy from both 2D and 3D perspectives.The inclusions are classified into eight categories according to chemistry and morphology.For the steel sample with a low Al content(0.5%),the inclusions are MnS,AlN-MnS,and Al_(2)O_(3)-MnS,among which Al_(2)O_(3)-MnS is the primary type.With the increase in Al content in the steel sample(to 5.2%),the populations of AlN and AlN-MnS inclusions of 1-3μm in diameter increase.A further increase in Al content(to 10.5%)leads to a significant decrease in the amount of AlN inclusions of 1-3μm in diameter,and an increase in the amount of AlN-MnS inclusions.The precipitation behavior during the phase transformation is also studied by FactSage 8.0 thermodynamic software,and a precipitation mechanism is proposed based on the calculation results.During the heat treatment,AlN inclusions re-precipitate out,due to the interactions between Al and dissolved N in the steel matrix.However,AlN inclusions cannot grow large because of unfavorable kinetic conditions.The re-precipitation phenomenon of AlN is predominant under low Al and high N conditions but not at high Al cases.
