Surface Nanocrystallization of Steel 20 Induced by Fast Multiple Rotation Rolling

In order to expand the application of steel 20 in precision device,fast multiple rotation rolling( FMRR) is applied to fabricate a nanostructured layer on the surface of steel 20. The FMRR samples are then Cr-Rare earth-boronized under low-temperature. The microstructure of the top surface layer is characterized by transmission electron microscopy( TEM). Microhardness of the top surface is measured by a Vickers microhardness tester. The boride layer is characterized by using scanning electron microscopy( SEM).Experimental results show that a nanostructured layer with their grain size range from 200 to 400 nm is obtained in the top surface layer. The microhardness of FMRR sample changes gradiently along the depth from about274 HV in the top surface layer to about 159 HV in the matrix,which is nearly 1.7 times harder than that of the original sample. The penetrating rate is enhanced significantly when the FMRR samples are Cr-Rare earthboronized at 600 ℃ for 6 h. Thickness of the boride layer increases to around 20 μm,which is nearly twice thicker than that of the original sample.

Effect of Surface Nanocrystallization Induced by Fast Multiple Rotation Rolling on Cr-Rare Earth-Boronizing for Steel 45 under Low-Temperature

In this paper, fast multiple rotation rolling （FMRR） is applied to fabricate a nanostructured layer on the surface of steel 45. The FMRR samples are then Cr-Rare earth-boronized under low-temperature. The boride layer is characterized by using Scanning electron microscopy （SEM） and X-ray diffraction （XRD）. Experimental results indicate that the thickness of the boride layer is greatly increased by surface nanocrystallization. The boride layer with relatively continuous structure instead of the zigzag teeth structure is obtained, and the penetrating rate is enhanced by 2. 5-3.7 times when the FMRR samples are Cr-Rare earth- boronized at the temperature of 570 %, 600℃ and 650℃ for 6 h. The boride layer fabricated on the FMRR sample consists of single phase Fe2B. Severe plastic deformation with the grain size of approximately 100 nm in the top surface layer of steel 45 is observed, and the thickness of the plastic deformation layer is about 30 6xm. The microstructure in the top surface layer is characterized by Transmission electron microscopy （TEM）. Grain boundaries are largely increased with high stacking fault energy after FMRR, leading to a significant enhancement of RE boron-chromizing speed.

Effect of Fast Multiple Rotation Rolling on Microstructure and Properties of Ti6Al4V Alloy

Using fast multiple rotation rolling(FMRR),a nanostructure layer was fabricated on the surface of Ti6Al4V alloy.The microstructure of the surface layer was investigated using optical microscopy,transmission electron microscopy,scanning electron microscopy,and X-ray diffraction.The results indicated that a nanostructured layer,with an average grain size of 72—83 nm,was obtained in the top surface layer,when the FMRR duration was 15 min.And the average grain size further reduced to 24—37 nm when the treatment duration increased to 45 min.High density dislocations,twins,and stacking faults were observed in the top surface layer.The microhardness of FMRR specimen,compared with original specimen,was significantly increased.A uniform,continuous and thicker compound layer was obtained in the top surface of FMRR sample,and the diffusion speed of N atom in the top surface layer was accelerated.FMRR treatment provides corrosion improvement.

Multiple rotation averaging using only the relative rotation angle

In this work,we propose multiple rotation averaging using only the relative rotation angle,which is a straightforward camera pose optimization method.We use the axis-angle representation to parameterize the rotation and use only relative rotation angles to constrain absolute rotations instead of complete relative rotations.When used with an inertial measurement unit(IMU),our method can obviate the need to estimate and maintain extrinsic parameters between the camera and IMU.This advantage makes our method immune to extrinsic parameters and flexible.We performed extensive evaluations on both synthetic data and publicly available real datasets,which showed that our method was comparable with the state-of-the-art method and achieved a significant gain in accuracy for the visual measurement when applied to the case in which the camera and IMU are tightly fixed.

Possible multiple antimagnetic rotational bands in odd-A^(103,105)Pd and^(109)Cd nuclei

The positive-parity signature partner bands in^(103,105)Pd and^(109)Cd nuclei are investigated using the classical particle-rotor model.Based on the systematic study of neighbouring nuclei,the signature partner bands of ^(105)Pd are assigned to theπ(g^(-4)_(9/2))■ν(g7/2h^(2)_(11/2))configuration,and this assignment is also supported by the present calculations.Furthermore,the calculated$B(E2)$values of such bands of ^(105)Pd reproduce the experimental values well and exhibit a decrease with increasing angular momentum,suggesting that these two bands may originate from antimagnetic rotation.Similar signature partner bands are also found in the neighboring^(103)Pd and^(109)Cd nuclei.The properties of both bands are in general agreement with the fingerprints of antimagnetic rotation,and thus the signature partner bands of^(103)Pd and^(109)Cd are suggested to be candidates for the multiple antimagnetic rotational bands of ^(105)Pd.In addition,the evolution of the two-shears-like mechanism for possible multiple antimagnetic rotational bands in^(103,105)Pd and^(109)Cd nuclei is examined by investigating the orientation of the angular momenta.