3 mm thick 400 MPa grade ultrafine grained ferritic steel plates were bead-on-plate welded by CO2 laser with heat input of 120-480 J/mm. The microstructures of the weld metal mainly consist of bainite, which form is l...3 mm thick 400 MPa grade ultrafine grained ferritic steel plates were bead-on-plate welded by CO2 laser with heat input of 120-480 J/mm. The microstructures of the weld metal mainly consist of bainite, which form is lower bainite plates or polygonal ferrite containing quantities of dispersed cementite particles, mixed with a few of low carbon martensite laths or ferrite, depending on the heat input. The hardness and the tensile strength of the weld metal are higher than those of the base metal, and monotonously increase as the heat input decreases. No softened zone exists in heat affected zone (HAZ). Compared with the base metal, although the grains of laser weld are much larger, the toughness of the weld metal is higher within a large range of heat input. Furthermore, as the heat input increases, the toughness of the weld metal rises to a maximum value, at which point the percentage of lower bainite is the highest, and then drops.展开更多
A great deal of research and practical production indicated that a perfectshape control system needs a precise prediction model of roll wear. According to the practical wearcurve of work roll in Angang ASP1700 hot str...A great deal of research and practical production indicated that a perfectshape control system needs a precise prediction model of roll wear. According to the practical wearcurve of work roll in Angang ASP1700 hot strip mill, which was measured by a roll-profilemeter, themodel of wear curve caused by one single strip was established. The prediction of work-roll wear wasachieved by combining Fortran language and practical technology parameters. The calculated resultsagreed well with the measured.展开更多
基金This work was supported by the‘973'ScienceTechnology Development Plan of the National Basic Research Foundation(No.1998061500)the 985'Foundation of Tsinghua University.
文摘3 mm thick 400 MPa grade ultrafine grained ferritic steel plates were bead-on-plate welded by CO2 laser with heat input of 120-480 J/mm. The microstructures of the weld metal mainly consist of bainite, which form is lower bainite plates or polygonal ferrite containing quantities of dispersed cementite particles, mixed with a few of low carbon martensite laths or ferrite, depending on the heat input. The hardness and the tensile strength of the weld metal are higher than those of the base metal, and monotonously increase as the heat input decreases. No softened zone exists in heat affected zone (HAZ). Compared with the base metal, although the grains of laser weld are much larger, the toughness of the weld metal is higher within a large range of heat input. Furthermore, as the heat input increases, the toughness of the weld metal rises to a maximum value, at which point the percentage of lower bainite is the highest, and then drops.
文摘A great deal of research and practical production indicated that a perfectshape control system needs a precise prediction model of roll wear. According to the practical wearcurve of work roll in Angang ASP1700 hot strip mill, which was measured by a roll-profilemeter, themodel of wear curve caused by one single strip was established. The prediction of work-roll wear wasachieved by combining Fortran language and practical technology parameters. The calculated resultsagreed well with the measured.
