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
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.
