The effects of deformation parameters and cooling rates on the aging behavior of AZ80+0.4%Ce

The extruded AZ80+0.4%Ce magnesium alloy was twisted in the temperature range of 300-380℃by using a Gleeble 3500 thermal simulation test machine with a torsion unit.The deformed cylindrical specimens were cooled at a cooling rate of 10℃/s or 0.1℃/s,respectively,and aged at 170℃.The microstructure analysis results showed that the grain size decreased with increasing specimen radial position from center(SRPC),and that the strong initial basal texture of the extruded magnesium alloy was weakened.Both continuous and discontinuous dynamic recrystallization mechanisms were involved in contributing to the grain refinement for all specimens investigated.And a novel extension twinning induced dynamic recrystallization mechanism was proposed for specimen deformed at 300℃.For the specimens deformed at 300℃and 340℃followed by a slow cooling rate(0.1℃/s),precipitates of various shapes(β-Mg_(17)Al_(12)),with the dominant precipitates being on the grains boundaries,appeared on the surface section.For specimen deformed at 380℃,lamellar precipitates(LPS)in the interiors of the grains were predominant.After aging,the LPS still dominated for specimens twisted at 380℃;however,the LPS gradually decreased with decreasing deformation temperatures from 380℃to 300℃.Dynamically precipitatedβ,especially those decorating the grain boundaries,changed the competition pictures for the LPS and precipitates of other shapes after aging.Interestingly,LPS dominated the areas for the center section of the specimens after aging regardless of deformation temperatures.Low temperature deformation with high SRPC followed by rapid cooling rate increased the micro hardness of the alloy after aging due to refined grain,reduced precipitates size,decreased lamellar spacing as well as strain hardening.

Effect of deformation parameters in unrecrystallization range on microstructural characteristics in Al-bearing hot-rolled TRIP steel

The scanning electron microscope,transmission electron microscope,optical microscope,X-ray diffraction and hardness tests were used to investigate the effect of deformation parameters in unrecrystallization range on microstructural characteristics in Al-bearing hot-rolled transformation-induced plasticity steel.The thermomechanical-controlled processing was carried out with thermomechanical simulation machine,and the samples were compressed to compression strains of 0,0.15,0.25 and 0.35 at compression temperatures of 850,900 and 950°C.The results showed that the volume fraction of polygonal ferrite increased with the increasing compression strain,while the volume fraction of retained austenite reached the maximum value at compression strain of 0.25.The volume fraction of polygonal ferrite decreased with the increasing compression temperature,whereas the volume fraction of retained austenite possessed the maximum value at compression temperature of 850°C.Some granular retained austenite was present in uncompressed samples,and some pearlite appeared at large compression strain,while the hardness of the samples exhibited the similar variation tendency to the volume fraction of retained austenite.

Deformation parameter changes in fission mass yields within the systematic statistical scission-point model

The fission fragment mass-yields are evaluated for pre-actinide and actinide isotopes using a systematic statistical scission point model.The total potential energy of the fissioning systems at the scission point is presented in approximate relations as functions of mass numbers,deformation parameters and the temperature of complementary fission fragments.The collective temperature,Tcoll,and the temperature of fission fragments,Ti,are separated and the effect of collective temperature on mass yields results is investigated.The fragment temperature has been calculated with the generalized superfluid model.The sum of deformation parameters of complementary fission fragments has been obtained by fitting the calculated results with the experimental data.To investigate the transitions between symmetric and asymmetric modes mass yields for pre-actinide and heavy actinides are calculated with this model.The transition from asymmetric to symmetric fission is well reproduced using this systematic statistical scission point model.The calculated results are in good agreement with the experimental data with Tcoll=2 Me V at intermediate excitation energy and with T_(coll)=1MeV for spontaneous fission.Despite the Langevin model,in the scission point model,a constraint on the deformation parameters of fission fragments has little effect on the results of the mass yield.

Metadynamic Recrystallization of the As-cast 42CrMo Steel after Normalizing and Tempering during Hot Compression

The existing researches of hot ring rolling process are mainly based on forged billet. Compared with the existing process, the new ring casting-rolling compound forming process has significant advantages in saving materials and energy, reducing emission and reducing the production cost. The microstructure evolution of the casting materials during hot deformation is the basis of the research of the new process. However, the researches on the casting materials are rare. The metadynamic recrystallization of the as-cast 42CrMo steel after normalizing and tempering during the hot compression is investigated. The tests are performed on the Gleeble-1500 thermal-mechanical simulator. The influence rule of the deformation parameters on the metadynamic recrystallization is obtained by analyzing the experimental data. The kinetic model of the rnetadynamic recrystallization is deduced. The analysis results show that the metadynamic recrystallization fraction increases with the increase of the deformation temperature and the strain rate. The metallographic experiments are used to investigate the influence rule of the deformation parameters on the grain size of the metadynamic recrystallization. The experimental results show that the grain of the metadynamic recrystallization could be refined with the increase of the strain rate and the decrease of the deformation temperature during hot compression. The occurrence of the metadynamic recrystallization during the hot deformation is more difficult in as-cast 42CrMo steel than in forged 42CrMo steel. The research can provide the foundation for the further research of the hot deformation behaviors of the as-cast structure and theoretical support for the new ring casting-rolling compound process.

Determination of No-recrystallization Temperature for a Nb-bearing Steel

The recrystallization behavior of a Nb-bearing steel was investigated during multipass deformation under continuous cooling conditions. By a series of six-pass compression tests conducted on a thermomechanical simulator, the effect of deformation parameters, including strain, strain rate and interpass time, on the no-recrystallization temperature （T） was determined. The results show that T decreases with increasing strain and also decreases slightly with increasing strain rate. The strain has more appreciable influence on the T compared with strain rate. When the interpass time is less than 10 s, the T decreases with increasing interpass time. The mathematical model of T was established considering the effect of pass strain, strain rate and interpass time. The calculated results agreed well with the actual experimental value.

Elasto-Plasticity Critical Corrosive Ratio Model for RC Structure Corrosive Expanding Crack

The parameter of filling expanding ratio n, plasticity factor k1 and deformation parameter k2 is raised, and then the elasto-plasticity critical corrosive ratio model for RC structure corrosive expanding crack based on elasto-plasticity theory is constructed in this paper. The influences of parameters such as filling expansion ratio n, plasticity factor kl, deformation parameter k2, Poisson ratio of concrete v, diameter of reinforced bar d and protective layer thickness c on the critical corrosive ratio are researched by theory analysis and experiments. The experimental results validate the accuracy of the model. According to the experimental study, the least squares solution is calculated as n = 1.8 ,k1 =0.61 ,k2 =0.5.

Upward Transition Probabilities B(E2)↑ Properties Study of Even-Even ^104-114Ru Nuclei

In this research work, the upward transition probabilities for the transition levels, 0+ → 2+, 2+ → 4+, 4+ → 6+ and 6+ → 8+ levels of even-even neutron rich 104-114Ru isotopes have been calculated by using the Global Best Fit (GBF) method. In addition, the associated parameters such as, Quadrupole moment and Deformation parameter of even-even 104-114Ru have been calculated. The dependency of these nuclear parameters shows the nuclear magic number tendency.

A New Parameter as an Indicator of the Degree of Deformation of Coals

The deformation of coal is effected by thermal effect, pressures and tectonic stress, and the tectonic stress is the principal influence factor. However, the proposition of a useful quantitative index that responds to the degree of deformation of coals quantitatively or semi-quantitatively has been a long-debated issue. The vitrinite reflectance ellipsoid, that is, the reflectance indication surface（RIS） ellipsoid is considered to be a strain ellipsoid that reflects the sum of the strain increment caused by stress in the process of coalification. It has been used to describe the degree of deformation of the coal, but the effect of the anisotropy on the RIS ellipsoid has not yet been considered with regards to non-structural factors. In this paper, Wei＇s parameter（ε） is proposed to express the deformation degree of the strain ellipsoid based on considering the combined influence of thermal effect, pressure and tectonic stress. The equation is as follows： ε=√[（ε_1-ε_0）~2＋（ε_2-ε_0）~2＋（ε_3-ε_0）~2]/3, where ε_1=lnR_（max）, ε_2=lnR_（int）, ε_3=lnR_（min）, and ε_0=（ε_1＋ε_2＋ε_3）/3. Wei＇s parameter represents the distance from the surface to the spindle of the RIS logarithm ellipsoid; thus, the degree of deformation of the strain ellipsoid is indicated quantitatively. The formula itself, meanwhile, represents the absolute value of the degree of relative deformation and is consequently suitable for any type of deformation of the strain ellipsoid. Wei＇s parameter makes it possible to compare degrees of deformation among different deformation types of the strain ellipsoid. This equation has been tested in four types of coal： highly metamorphic but weakly deformed coal of the southern Qinshui Basin, highly metamorphic and strongly deformed coal from the Tianhushan coal mining area of Fujian, and medium metamorphic and weakly or strongly deformed coal from the Huaibei Coalfield. The results of Wei＇s parameters are consistent with the actual deformation degrees of the coal reservoirs determined by other methods, which supports the effectiveness of this method. In addition, Wei＇s parameter is an important complement to the indicators of the degrees of deformation of coals, which possess certain theoretical significance and practical values.

Hot Deformation Behavior of a Novel Ni-Cr-Mo-B Ultra-heavy Plate Steel by Hot Compression Test

Hot deformation behavior of a novel Ni-Cr-Mo-B heavy plate steel was studied by hot compression tests,which were conducted on a Gleeble-3800thermo-mechanical simulator corresponding to the temperature range of850-1 150℃ with the strain rates of 0.01-10s-1 and the true strain of 0.8.The results suggest that the majority of flow curves exhibit a typical dynamic recrystallization（DRX）behavior with an apparent single peak stress followed by agradual fall towards a steady-state stress.Important characteristic parameters of flow behavior as critical stress/strain for initiation of DRX and peak and steady-state stress/strain were derived from curves of strain hardening rate versus stress and stress versus strain,respectively.Material constants of the investigated steel were determined based on Arrhenius-type constitutive equation,and then the peak stress was predicted by the equation with the hot deformation activation energy of 379 139J/mol,and the predicted values agree well with the experimental values.Furthermore,the effect of Zener-Hollomon parameter on the characteristic points of flow curves was studied using the power law relation,and the ratio of critical stress and strain to peak stress and strain were found to be 0.91and0.46,respectively.

Kinetic energy distribution for neutron-induced fission of neptunium isotopes

The mean total kinetic energy as a function of fission fragments,the<TKE>distribution,is presented for neutron-induced fission of ^(235-239)Np using the scission point model.The calculated results of<TKE>for neutron-induced fission of ^(237,238) Np are compared with the available experimental data to obtain the deformation parameters in the scission point model.The deformation parameters of fission fragments are discussed at the scission point.The calculated results are also compared with the results from other methods and with experimental data.The behavior of the<TKE>distribution is then studied for the neutron-induced fission of actinides.This indicates that the<TKE>values for neutron-induced fission of actinides with odd mass numbers are greater than for those with even mass numbers.

B(E2) value of even-even ^(108-112)Pd isotopes by interacting boson model-1

This work studies the systematic reduced transition probabilities B（E2）↓, intrinsic quadrupole moments and deformation parameters of Pd isotopes with even neutrons from N =62 to 66. The downward reduced transition probabilities B（E2）↓from gamma transition 8^＋to 6^＋, 6^＋ to 4^＋, 4^＋ to 2^＋ and 2^＋ to 0＋states of even-even108 112Pd isotopes were calculated by the Interacting Boson Model（IBM-1） and compared with the available previous experimental results. The ratio of the excitation energies of the first 4＋and the first 2＋excited states, R4/2, is also studied for the classification of symmetry of these nuclei. Furthermore we have studied systematically the transition rate R = B（E2： L＋ →（L 2）＋）/B（E2 ： 2＋ →0＋） of some of the low-lying quadrupole collective states in comparison with the available experimental data. The associated quadrupole moments and deformation parameters have been calculated. The results of this calculation are in good agreement with the corresponding available experimental data. The108 112Pd isotopes show the O（6） symmetry.

Drag force on a moving heavy quark with deformed string configuration

To study drag force on a moving heavy quark through a plasma,we use a deformed AdS spacetime,in which deformation parameter c describes non-conformality in AdS/QCD.In this case,the quark is mapped to a probe string in the AdS space.Considering the probable contribution of the deformation parameter in the probe string,we apply a general form of c-dependent string ansatz in the drag force computation.Then,we find the acceptable value of this parameter as it satisfies QCD calculations.Using this result,we also discuss the diffusion constant which is in agreement with the phenomenological result for the non-relativistic limit.Also,we show that while in absence of a deformation parameter,the probe string is a strictly increasing function of radial coordinate,the c-dependent probe string has a maximum value versus z.

Systematic description of nuclear electric quadrupole moments

The nuclear electric quadrupole moment （NQM） is one of the fundamental bulk properties of the nucleus with which nuclear deformations can be investigated. The number of measured NQMs is significantly less than that of known masses, and there is still no global NQM formula for all bound nuclei. In this paper, we propose an analytical formula, which includes the shell corrections and which is the function of the charge number, mass number, spin, charge radius, and nuclear deformation, for calculating the NQMs of all bound nuclei. Our calculated NQMs of 524 nuclei in their ground states are reasonable compared to the experimental data based on the nuclear deformation parameters derived from the Weizsacker-Skyrme （WS） nuclear mass models. Smaller rms deviations between the calculated NQMs and experimental data indicate that the deformation parameters predicted from the WS mass models are reasonable. In addition, 161 unmeasured NQMs with known spins are also predicted with the proposed formula.

Study of ~3He inelastic scattering on ^(13)C and ^(14)C at 37.9 MeV

The differential cross sections of elastic and inelastic scattering of ~3He ions on ^（13）C and ^（14）C have been studied at an energy of 37.9 MeV with a double folding model based on M3Y-Reid effective nucleon-nucleon interaction.The resulted parameters have been used for the standard Distorted Wave Born Approximation calculations of angular distributions corresponding to different excitations levels of ^（13）C and ^（14）C and deformation parameters have been deduced.

Chiral geometry in multiple chiral doublet bands

The chiral geometry of multiple chiral doublet bands with identical configuration is discussed for different triaxial deformation parameters γ in the particle rotor model with πh11/2×γh11/2^-1.The energy spectra,electromagnetic transition probabilities B（M1） and B（E2）,angular momenta,and K-distributions are studied.It is demonstrated that the chirality still remains not only in the yrast and yrare bands,but also in the two higher excited bands whenγ deviates from 30°.The chiral geometry relies significantly on γ,and the chiral geometry of the two higher excited partner bands is not as good as that of the yrast and yrare doublet bands.