The method based on transient heat transfer model is adopted to simulate electro-slag remelting process. The calculated results of the model show that the process is in the quasi-steady state, and the shape of pool re...The method based on transient heat transfer model is adopted to simulate electro-slag remelting process. The calculated results of the model show that the process is in the quasi-steady state, and the shape of pool remains unchanged when the height of ingot is approximately 2.5-3 times the thickness of slab ingot. The change in the shape of pool is found to be strongly dependent on the pattern of melting rate, and hence, the power input; the depth of the molten pool increases with the increase in melting speed. It is concluded that a transient heat transfer model has to be used to obtain reliable input information for the entire, operatina time.展开更多
The influence of ingot segregation on quenching distortion of gear steel was investigated in this paper. The results show that the shape of ingot segregation of rod steel depends on the shape of continuous casting (C...The influence of ingot segregation on quenching distortion of gear steel was investigated in this paper. The results show that the shape of ingot segregation of rod steel depends on the shape of continuous casting (CC) molds ,and that the distortion of gear steel with square ingot segregation is uniform, while that of gear steel with rectangular ingot segregation is anisotropic. After quenching,the outer circle of the ring sample with a large rectangular segregation area is distorted into an oval shape. No obvious element segregation has been found in the rod steel produced through the rectangular CC mold. Obvious difference in density has been detected at the cross section of rod steel. It suggests that center porosity may be the main reason for the strong impact of segregation on heat treatment distortion of gear steel.展开更多
The rectangle core plate of all-steel buckling-restrained braces(BRBs) usually exhibit obvious local buckling, due to the lack of longitudinal restraint from the encasing tube. To eliminate the undesirable effects, a ...The rectangle core plate of all-steel buckling-restrained braces(BRBs) usually exhibit obvious local buckling, due to the lack of longitudinal restraint from the encasing tube. To eliminate the undesirable effects, a novel steel BRB is proposed. In this new-type steel BRB, two T-shaped steels are adopted as the minor restraint elements to restrain the core plate instead of infilled concrete or mortar. Meanwhile, the ingot-iron material with low yielding strength and high elongation is applied to the steel core to study the mechanical properties of steel BRBs. To validate the theoretical requirements for the width-to-thickness ratio of the steel core and the thickness of angle steel, quasi-static tests of eight specimens were conducted. The tests focused on the energy dissipation capacity and failure modes of the proposed steel BRBs. Nonlinear finite element analysis was also carried out to validate the experimental results. Both the aforementioned results imply that appropriately designed steel BRBs can meet the performance requirements for BRB components.展开更多
文摘The method based on transient heat transfer model is adopted to simulate electro-slag remelting process. The calculated results of the model show that the process is in the quasi-steady state, and the shape of pool remains unchanged when the height of ingot is approximately 2.5-3 times the thickness of slab ingot. The change in the shape of pool is found to be strongly dependent on the pattern of melting rate, and hence, the power input; the depth of the molten pool increases with the increase in melting speed. It is concluded that a transient heat transfer model has to be used to obtain reliable input information for the entire, operatina time.
文摘The influence of ingot segregation on quenching distortion of gear steel was investigated in this paper. The results show that the shape of ingot segregation of rod steel depends on the shape of continuous casting (CC) molds ,and that the distortion of gear steel with square ingot segregation is uniform, while that of gear steel with rectangular ingot segregation is anisotropic. After quenching,the outer circle of the ring sample with a large rectangular segregation area is distorted into an oval shape. No obvious element segregation has been found in the rod steel produced through the rectangular CC mold. Obvious difference in density has been detected at the cross section of rod steel. It suggests that center porosity may be the main reason for the strong impact of segregation on heat treatment distortion of gear steel.
基金Supported by:Basic Research Foundation of Institute of Engineering Mechanics,CEA under Grant No.2017A01the Earthquake Scientific Research Funds Program under Grant No.201508023
文摘The rectangle core plate of all-steel buckling-restrained braces(BRBs) usually exhibit obvious local buckling, due to the lack of longitudinal restraint from the encasing tube. To eliminate the undesirable effects, a novel steel BRB is proposed. In this new-type steel BRB, two T-shaped steels are adopted as the minor restraint elements to restrain the core plate instead of infilled concrete or mortar. Meanwhile, the ingot-iron material with low yielding strength and high elongation is applied to the steel core to study the mechanical properties of steel BRBs. To validate the theoretical requirements for the width-to-thickness ratio of the steel core and the thickness of angle steel, quasi-static tests of eight specimens were conducted. The tests focused on the energy dissipation capacity and failure modes of the proposed steel BRBs. Nonlinear finite element analysis was also carried out to validate the experimental results. Both the aforementioned results imply that appropriately designed steel BRBs can meet the performance requirements for BRB components.