In the continuous casting production of medium carbon steel (whose mass fraction of carbon is 0.09 % to 0.16 %) and high strength low alloy steel (whose mass fraction of Mn is 0.90 % to 1.40 %), flecks occurring the m...In the continuous casting production of medium carbon steel (whose mass fraction of carbon is 0.09 % to 0.16 %) and high strength low alloy steel (whose mass fraction of Mn is 0.90 % to 1.40 %), flecks occurring the most often are usually longitudinal and star cracks. In additional to the employment of a galvanized plate mould, two kinds of fluxes with special properties were studied and used to harmonize the conflicts between the function of heat transfer and lubrication. An industrial application revealed that the crystallizing temperature (Tc) and crystal ratio (R) of fluxes have a crucible effect on impeding the occurrence of above defects on a slab surface. In the case of slab section (180 to 240) mm(1000 to 1400) mm and casting speed Vc of (0.7 to 1.2) m/min, the optimized parameters of fluxes are Tc of (1170 to 1190) ℃, R of 80 % to 95 % for medium carbon steel, and Tc of (1100 to 1150) ℃, plus R of 40 % to 60 % for high strength low alloy steel.展开更多
Continuous roll forming(CRF) is a novel forming process for three-dimensional surface parts,in which a pair of bendable forming rolls is used as sheet metal forming tool.By controlling the gap between the upper and lo...Continuous roll forming(CRF) is a novel forming process for three-dimensional surface parts,in which a pair of bendable forming rolls is used as sheet metal forming tool.By controlling the gap between the upper and lower forming rolls,sheet metal is non-uniformly extended in the longitudinal direction while it is bent in the transverse direction during the rolling process.As a result,longitudinal bending is gained and a doubly curved surface is formed.With the rotations of the forming rolls,the sheet metal is deformed consecutively,and a three-dimensional surface part is shaped continuously.In this paper,the mechanism of the three-dimensional surface formation in CRF is set forth.Through theoretical analysis of the CRF process,the governing equations for the bending deformation in rolling process are presented.Based on the simplification on the deformation and material model,the formulation to calculate the longitudinal bending deformation is derived,and the methods to design the compression ratio and the roll gap are given,the effects of compression ratio of rolling and the width of blank sheet on the longitudinal bending curvature are analyzed.The forming experiments on typical surface parts and measured results show that forming results with good precision can be obtained by CRF process.展开更多
文摘In the continuous casting production of medium carbon steel (whose mass fraction of carbon is 0.09 % to 0.16 %) and high strength low alloy steel (whose mass fraction of Mn is 0.90 % to 1.40 %), flecks occurring the most often are usually longitudinal and star cracks. In additional to the employment of a galvanized plate mould, two kinds of fluxes with special properties were studied and used to harmonize the conflicts between the function of heat transfer and lubrication. An industrial application revealed that the crystallizing temperature (Tc) and crystal ratio (R) of fluxes have a crucible effect on impeding the occurrence of above defects on a slab surface. In the case of slab section (180 to 240) mm(1000 to 1400) mm and casting speed Vc of (0.7 to 1.2) m/min, the optimized parameters of fluxes are Tc of (1170 to 1190) ℃, R of 80 % to 95 % for medium carbon steel, and Tc of (1100 to 1150) ℃, plus R of 40 % to 60 % for high strength low alloy steel.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51275202 and 51075186)
文摘Continuous roll forming(CRF) is a novel forming process for three-dimensional surface parts,in which a pair of bendable forming rolls is used as sheet metal forming tool.By controlling the gap between the upper and lower forming rolls,sheet metal is non-uniformly extended in the longitudinal direction while it is bent in the transverse direction during the rolling process.As a result,longitudinal bending is gained and a doubly curved surface is formed.With the rotations of the forming rolls,the sheet metal is deformed consecutively,and a three-dimensional surface part is shaped continuously.In this paper,the mechanism of the three-dimensional surface formation in CRF is set forth.Through theoretical analysis of the CRF process,the governing equations for the bending deformation in rolling process are presented.Based on the simplification on the deformation and material model,the formulation to calculate the longitudinal bending deformation is derived,and the methods to design the compression ratio and the roll gap are given,the effects of compression ratio of rolling and the width of blank sheet on the longitudinal bending curvature are analyzed.The forming experiments on typical surface parts and measured results show that forming results with good precision can be obtained by CRF process.
