TA2/Q235B复合板不同作用面成形极限及界面损伤行为

采用Nakazima实验法对不同尺寸的退火态TA2/Q235B复合板样品进行胀形实验,研究不同作用面对TA2/Q235B复合板的成形极限和界面损伤行为的影响。结果表明,当凹模与碳钢侧接触时,由于接触材料、界面变形协调能力和应变状态的不同,复合板的胀形高度和成形极限增加,其中R140试样的极限拱高达到最大值(46.17 mm),R60和R180试样在3个方向上的厚度减薄量和界面裂纹更大。此外,由于硬度和拉应力不同,两组样品中所有的水平和斜向孔都向纯钛侧延伸。

Mechanism of high-energy pulsed current-assisted rolling of 08AL carbon steel ultra-thin strip

To improve the plastic deformation performance of a 08AL carbon steel ultra-thin strip,a pulsed electric field was integrated into the plastic processing of the ultra-thin strip,and the effects of high-energy current on its deformation ability were investigated.Current-assisted tensile tests were employed,and the results clarified that the pulsed current could reduce the activation energy of faults and promoted dislocation slip within grains and at grain boundaries,leading to a decrease in the deformation resistance of the metal and an increase in its plastic properties.Under the current density of 2.0 A/mm2,the yield strength,tensile strength,and elongation of the rolled sample reached 425 MPa,467 MPa,and 12.5%,respectively.During the rolling process,it was found that the pulsed current promoted the dynamic recrystallization of the ultra-thin strip,reduced its dislocation density and deformation resistance,and promoted the coordinated deformation of the metal.

Effect of cooling rate on solidification microstructure and mechanical properties of TiB2-containing TiAl alloy

Effects of cooling rate and 0.25 at.%TiB2 addition on solidification microstructure and mechanical properties of Ti−48Al−2Cr−2Nb alloys fabricated by the investment casting with different thicknesses were studied.The results show that with the cooling rate increasing from 37 to 2×102 K/s,the solidification path of the studied alloys is unchanged.The grain size of the matrix alloy is refined from 650 to 300μm,while the grain size of Ti−48Al−2Cr−2Nb−TiB2 is reduced from 550 to 80μm.The lamellar spacing of matrix alloy is reduced from 360 to 30 nm with increasing the cooling rate from 37 to 2×102 K/s,while TiB2 addition shows little refinement effect on the lamellar spacing.Ti−48Al−2Cr−2Nb−TiB2 sample under medium cooling rate(69 K/s)exhibits superior microhardness(HV 550)and ultimate tensile strength(570 MPa)among the studied alloys.The refined grain size,lamellar spacing and fine TiB2 particles could account for the favorable mechanical properties of the studied TiB2-containing alloy.The microstructure evolution was discussed in light of cooling rate,constitutional supercooling and borides addition.

A new method for evaluating wedges of steel plates and strips

To overcome the inaccuracy problem of the traditional wedge evaluation of steel plates and strips caused by the ran-domness of the thicknesses of two local points and improve the reliability of the wedge index,the double-centroid method for the wedge evaluation was proposed,and a model based on the centroid theory was established.Meanwhile,an integral model for the discrete thickness values of the cross-section profiles was derived.The discussion focused on the distinct characteristics of the two-point method,asymmetric method,and double-centroid method in evaluating the asymmetric distribution of cross-sections.The three methods were employed to evaluate the wedge values of both the theoretical and measured cross-sections of steel plates and strips,and the accuracies of three wedge evaluation models were analyzed and discussed.The results showed that the double-centroid method objectively reflects the degree and variation characteristics of the wedge values of the cross-sections of steel plates and strips,and this method is feasible,reliable,and outstanding.

Interfacial bonding mechanism of Cu/Al composite plate produced by corrugated cold roll bonding

Corrugated cold roll bonding(CCRB) produces metal composite plate with improved mechanical properties compared with conventional methods,but the interfacial mechanism is not fully understood.Here,Cu/Al composite plate with good plate shape was produced by CCRB,and the bonding mechanism and strength along the corrugated interface were studied by experiments and finite element simulations.The results showed that the average bonding strength of Cu/Al composite plate produced by CCRB was nearly twice that of conventional composite plate at an average reduction of 40% during rolling.Strong friction shear stresses occurred at the interface of the corrugated composite plate,which promoted the plastic deformation of the metals and accelerated the rupture of the brittle interfacial layer.Electron backscattered diffraction analysis showed that higher degrees of grain elongation and refinement occurred in the matrices at the front waist and trough due to the stronger normal and shear stresses.Energy-dispersive spectroscopy line scans showed that the thickest atomic diffusion layer occurred at the front waist.The present combination of experimental and computational analyses provides insights into the underlying mechanism of mechanically improved metal composites prepared by CCRB.

Influence of lateral displacement on strip shape during cold rolling

The theory of metal plastic deformation is an important part of the strip shape control theories. In order to control the shape and gauge accurately during cold thin strip rolling, the mechanism of the metal lateral flow must be revealed clearly. Therefore, the lateral displacement of thin strip was studied by the grid method. Those grids with a line thickness of 10 μm and clear boundaries were successfully manufactured on the strip surface using lithography. Then, the effects of reduction, front and back tension, and taper angle of the first intermediate roll on the metal lateral flow were studied. The strip shape was calculated with and without considering the lateral displacement; furthermore, the calculations were compared with the measured results. The results show that the calculations with considering the lateral displacement are closer to the measured results. In addition, the comparison of finite element analysis results with the experimental results indicates that the test method was reliable.