In accordance with the minimum degree of disregistry mechanism in oxide metallurgy, the intragranular acicular ferrite (IAF) generated by microalloying elements in austenite was studied. Herein, the effect of Mg treat...In accordance with the minimum degree of disregistry mechanism in oxide metallurgy, the intragranular acicular ferrite (IAF) generated by microalloying elements in austenite was studied. Herein, the effect of Mg treatment on the microstructure and toughness of the heat-affected zone (HAZ) in shipbuilding steel was investigated. Mg treatment produced inclusions that influenced the formation of acicular ferrite in the microstructure. This refined the HAZ microstructure and improved its toughness. Electron backscatter diffraction was used to determine the oxides of titanium and the MgO Al_(2)O_(3) or MgAl_(2)O_(4) complex inclusions that induced the formation of IAF. MnS precipitated on MgAl_(2)O_(4) on a specific habit plane and in a specific direction. MnS had a specific orientation relationship with MgAl_(2)O_(4), i.e., f100gMgAl_(2)O_(4) //{100}MnS. The 35-mm-thick plate obtained in the industrial test after welding at a welding heat input of 120 kJ/cm had an average impact absorbed energy of 282.7 J at - 40 ℃ and 2 mm from the weld joint in the HAZ. The twodimensional disregistry index between inclusions can be used as the basis for controlling their distribution and adsorption force. Microalloy addition in the order of Al-Mg-Ti is key to obtaining abundant dispersion and fine nucleation in austenite.展开更多
The formation and growth behavior of inclusions in the liquid steel were studied based on 45 steel by virtue of high temperature confocal laser scanning microscope.The structures of all kinds of complex inclusions for...The formation and growth behavior of inclusions in the liquid steel were studied based on 45 steel by virtue of high temperature confocal laser scanning microscope.The structures of all kinds of complex inclusions formed in the process of cooling and solidification of liquid steel were analyzed,and disregistries between various inclusions were calculated.The results showed that inclusions with high melting point precipitated firstly,and inclusions with low disregistries precipitated later.The latter precipitated and grew up on the surface of the former,and finally clear layered complex inclusions formed.The low disregistry mechanism could not fully explain the forming reasons of all complex inclusions,but no matter which kind of mechanism leading to the formation of complex inclusions,its basic principle is that the first precipitated phase provides a low nuclear power interface for the latter,which can reduce the nucleation interface and strain energy barrier of the latter.展开更多
基金support from the National Natural Science Foundation of China(Nos.52004094 and 51874137)the Hebei Province Natural Science Fund Project(E2021209037.E2020209044,_and E2020209036)Fundamental Innovation Team of High Quality Clean Stcel in Tangshan_fromTangshan Scienceand Technology Bureau(21130209D).
文摘In accordance with the minimum degree of disregistry mechanism in oxide metallurgy, the intragranular acicular ferrite (IAF) generated by microalloying elements in austenite was studied. Herein, the effect of Mg treatment on the microstructure and toughness of the heat-affected zone (HAZ) in shipbuilding steel was investigated. Mg treatment produced inclusions that influenced the formation of acicular ferrite in the microstructure. This refined the HAZ microstructure and improved its toughness. Electron backscatter diffraction was used to determine the oxides of titanium and the MgO Al_(2)O_(3) or MgAl_(2)O_(4) complex inclusions that induced the formation of IAF. MnS precipitated on MgAl_(2)O_(4) on a specific habit plane and in a specific direction. MnS had a specific orientation relationship with MgAl_(2)O_(4), i.e., f100gMgAl_(2)O_(4) //{100}MnS. The 35-mm-thick plate obtained in the industrial test after welding at a welding heat input of 120 kJ/cm had an average impact absorbed energy of 282.7 J at - 40 ℃ and 2 mm from the weld joint in the HAZ. The twodimensional disregistry index between inclusions can be used as the basis for controlling their distribution and adsorption force. Microalloy addition in the order of Al-Mg-Ti is key to obtaining abundant dispersion and fine nucleation in austenite.
基金Sponsored by Natural Science Foundation of Hebei Province of China(E2013209207)
文摘The formation and growth behavior of inclusions in the liquid steel were studied based on 45 steel by virtue of high temperature confocal laser scanning microscope.The structures of all kinds of complex inclusions formed in the process of cooling and solidification of liquid steel were analyzed,and disregistries between various inclusions were calculated.The results showed that inclusions with high melting point precipitated firstly,and inclusions with low disregistries precipitated later.The latter precipitated and grew up on the surface of the former,and finally clear layered complex inclusions formed.The low disregistry mechanism could not fully explain the forming reasons of all complex inclusions,but no matter which kind of mechanism leading to the formation of complex inclusions,its basic principle is that the first precipitated phase provides a low nuclear power interface for the latter,which can reduce the nucleation interface and strain energy barrier of the latter.
