The inclusion characteristics in 55SiCr spring steel with different contents of titanium and calcium were investigated.The chemical compositions of steel samples were detected by inductively coupled plasma optical emi...The inclusion characteristics in 55SiCr spring steel with different contents of titanium and calcium were investigated.The chemical compositions of steel samples were detected by inductively coupled plasma optical emission spectrometer,and the inclusion characteristics was determined by field emission scanning electron microscopy(FE-SEM)and energy-dispersive spectroscopy.The results show that the Ti/Al ratio should be kept at less than 1,and the content of calcium should be controlled between 0.0015 and 0.0025 wt.%in Si-Mn-Al deoxidized steel,so that more solid inclusions can be converted to liquid inclusions.Moreover,the high Ti content in melts is the direct cause of the high proportion of Ti_(3)O_(5) in the inclusions,which involves[Ti]to reduce SiO_(2) and A1_(2)O_(3) in inclusions.In addition,calcium treatment can reduce the content of Ti_(3)O_(5) in inclusions,and the degree of reduction is closely related to the content of[O].The thermodynamic calculation of Fe-Si-Mn-Cr-Al-Ti-Ca-O molten steel system during solidification process was performed by FactSage software,taking all types of inclusions into account,such as titanium oxide,calcium oxide,aluminum oxide,silicon oxide,manganese oxide,calcium titanate,mullite,calcium aluminate,and liquid inclusion.The inclusion type of calculation results was in accordance with the experimental results at 1550℃,and TiO_(x) aggregation behavior was consistent with the Ti_(2)O_(3)-containing precipitation phase.展开更多
To reveal the effects of magnesium on the evolution of oxide and sulphide inclusions in liquid iron, both thermodynamic calculations and deoxidization experiments were carried out. The samples extracted from the liqui...To reveal the effects of magnesium on the evolution of oxide and sulphide inclusions in liquid iron, both thermodynamic calculations and deoxidization experiments were carried out. The samples extracted from the liquid iron were polished and analyzed by optical microscopy and scanning electron microscopy. The results showed that magne sium could modify oxide and sulphide inclusions simultaneously. Spherical MgO and irregular spinel inclusions were observed in the samples. The elongated MnS inclusions were replaced by small MgO · MgS or MgO · MgS · MnS complex inclusions, and the sulphides were distributed dispersively. The evolution mechanisms of inclusions were discussed comprehensively, and a proposed model for the formation of oxysulphide was set up.展开更多
Effect of Mg addition on the compositions of inclusions were studied. The results show that Mg can minimize the inclusions of steel obviously. Under the present condition, Mg deoxidation products of low-S content expe...Effect of Mg addition on the compositions of inclusions were studied. The results show that Mg can minimize the inclusions of steel obviously. Under the present condition, Mg deoxidation products of low-S content experimental steel would be changed in the order of Al2O3→MgAl2O4→Mg–Al–O–S→Mg–O–S. Mg deoxidation products of high-S content experimental steel generate Mg–S(–O)+MnS type inclusions, except for usual oxysulfide. And it is consistent with the results of thermodynamics calculation. Mg is preferred to react with oxide, compared with sulfide. The reaction reaches the equilibrium after 1 min or 5 min. It shows that the number and diameter of inclusions in all experimental steel samples are well under control, helping to improve the properties of steel.展开更多
基金The financial supports from the National Natural Science Foundation of China(51904346)the Introduce Talents Research Fund of Central South University are greatly acknowledged.
文摘The inclusion characteristics in 55SiCr spring steel with different contents of titanium and calcium were investigated.The chemical compositions of steel samples were detected by inductively coupled plasma optical emission spectrometer,and the inclusion characteristics was determined by field emission scanning electron microscopy(FE-SEM)and energy-dispersive spectroscopy.The results show that the Ti/Al ratio should be kept at less than 1,and the content of calcium should be controlled between 0.0015 and 0.0025 wt.%in Si-Mn-Al deoxidized steel,so that more solid inclusions can be converted to liquid inclusions.Moreover,the high Ti content in melts is the direct cause of the high proportion of Ti_(3)O_(5) in the inclusions,which involves[Ti]to reduce SiO_(2) and A1_(2)O_(3) in inclusions.In addition,calcium treatment can reduce the content of Ti_(3)O_(5) in inclusions,and the degree of reduction is closely related to the content of[O].The thermodynamic calculation of Fe-Si-Mn-Cr-Al-Ti-Ca-O molten steel system during solidification process was performed by FactSage software,taking all types of inclusions into account,such as titanium oxide,calcium oxide,aluminum oxide,silicon oxide,manganese oxide,calcium titanate,mullite,calcium aluminate,and liquid inclusion.The inclusion type of calculation results was in accordance with the experimental results at 1550℃,and TiO_(x) aggregation behavior was consistent with the Ti_(2)O_(3)-containing precipitation phase.
基金Sponsored by National Natural Science Foundation of China(50904017)Fundamental Research Funds for the Central Universities of China(N120502004,N120602005)
文摘To reveal the effects of magnesium on the evolution of oxide and sulphide inclusions in liquid iron, both thermodynamic calculations and deoxidization experiments were carried out. The samples extracted from the liquid iron were polished and analyzed by optical microscopy and scanning electron microscopy. The results showed that magne sium could modify oxide and sulphide inclusions simultaneously. Spherical MgO and irregular spinel inclusions were observed in the samples. The elongated MnS inclusions were replaced by small MgO · MgS or MgO · MgS · MnS complex inclusions, and the sulphides were distributed dispersively. The evolution mechanisms of inclusions were discussed comprehensively, and a proposed model for the formation of oxysulphide was set up.
基金Item Sponsored by National Natural Science Foundation of China(50904017)Fundamental Research Funds for the Central Universities of China(N120502004,N120602005)
文摘Effect of Mg addition on the compositions of inclusions were studied. The results show that Mg can minimize the inclusions of steel obviously. Under the present condition, Mg deoxidation products of low-S content experimental steel would be changed in the order of Al2O3→MgAl2O4→Mg–Al–O–S→Mg–O–S. Mg deoxidation products of high-S content experimental steel generate Mg–S(–O)+MnS type inclusions, except for usual oxysulfide. And it is consistent with the results of thermodynamics calculation. Mg is preferred to react with oxide, compared with sulfide. The reaction reaches the equilibrium after 1 min or 5 min. It shows that the number and diameter of inclusions in all experimental steel samples are well under control, helping to improve the properties of steel.
