Subsurface Deformation Research Articles

Flooded drilling of Inconel 718 using graphene incorporating cutting fluid

In order to improve drilling performance of Inconel 718 alloy, a cutting fluid (CF) consisting of 70% water and 30% vegetable oil blended with graphene nanoplatelets was used. Sliding of Inconel 718 workpiece using WC-Co drills with CF containing 54 × 10−5 wt% graphene (GCF) reduced the coefficient of friction (COF) between the tool and workpiece surfaces from 0.16 to 0.08 and resulted in the formation of tribolayers. The maximum drilling torque of 6 Nm for CF was reduced to 2 Nm using GCF. Additionally, arithmetic mean height (Sa) of drilled surfaces decreased from 8 to 4 μm and a reduction in the amount of material transferred from the Inconel 718 to the cutting edge of the drill was observed. The drilling temperature decreased from 150 to 100 °C using GCF during the process. Subsurface plastic deformation that occurred at the drilled surfaces of Inconel 718 was examined by cross-sectional optical microscopy which revealed that both the depth of deformation zone and the magnitude of subsurface strains were lower compared with flooded drilling. Therefore, graphene added in small quantities to the cutting fluid can provide an energy efficient method for drilling of Inconel 718. Graphical abstract

Analytical model and experimental verification of Poisson burr formation in ductile metal machining

Previous investigations on the theoretical model to predict burr dimensions have normally been confined to a single geometric model, and the findings that have been proposed rarely take into account the influence of multi-physics factors on burr formation in the complex machining process. This paper proposes an analytical model to reveal subsurface plastic deformation behavior in machining of ductile material. This model is developed based on coupled thermo-mechanical factors. More importantly, the material property and tool edge arc are taken into consideration. According to the proposed model, the two approaches are presented to predict Poisson burr height and root thickness. Moreover, the material flow and burr formation mechanism are further investigated at great length. The effects of machining parameters and material properties on burr formation are analyzed and discussed in terms of plastic deformation behavior. The results show that this proposed model can describe burr morphology and predict burr size accurately. Poisson burr generation has a great sensitivity to machining parameters, as well as material property, and the transition of burr morphology is caused by severe lateral material flow owing to material softening effect at high temperature. There is the synchronous interaction between machining parameters and material property influencing burr formation. As a result, this study provides a valuable theoretical reference and basis for the deburring energy minimization, high surface quality, and machining parameters optimization.

Micromachining imposed subsurface plastic deformation in single-crystal aluminum

Mechanical removal of metal induces deformation and changes to microstructural characteristics of the newly created surfaces. The mode and extent of deformation can be difficult to predict since it depends on the local crystallographic orientation, which varies significantly for polycrystalline metals. In this work, we analyzed the deformation mode and extent beneath machined surfaces of different crystallographic orientations. This was accomplished by orthogonal micromachining of single-crystal aluminum along six different crystallographic orientations orthogonal to the sample [111] zone-axis, followed by electron backscatter diffraction (EBSD) analysis to evaluate the resulting subsurface microstructure and crystal lattice rotation. The results indicate that differences in the initial material crystallographic orientation produce significant variations in the depth of deformation (compared to the uncut chip thickness), the degree of grain refinement and the extent of lattice rotations. We grouped the orientation as “hard” or “soft” based on the measured cutting force. The soft orientations exhibit deformation modes consisting of shear bands and lattice rotations; whereas hard orientations exhibit deformation modes consistent with strain hardening: localized dynamic recrystallization, highly entangled dislocations and minimal crystal lattice rotations. The depth of subsurface deformation for some orientations was extensive, reaching depths far greater than the uncut chip thicknesses. Overall, we conclude that the cutting force required to machine a given orientation does provide some insight on the local deformation mode, and orientations can be easier or harder to machine based on local susceptibility to shear and lattice rotation.

Machinability maps – Towards a mechanistic understanding of the machining of TI-6AL-4V and TIMETAL 407

In recent years, new titanium alloys with improved “machinability” have been developed, to provide manufacturers with alloys that can be machined to final dimensions at higher metal removal rates. One such alloy, TIMETAL® 407 (Ti-407), was developed to replace Ti-6Al-4V (Ti-64) in applications where energy absorption prior to failure is a key property requirement. In this study, a combination of large scale turning trials was used to characterise the full range of machining criteria, including: (1) tool life, (2) chip formation and (3) subsurface microstructural deformation. The machining response of the two alloys was summarised in easy-to-visualise machinability maps: to aid the machining supply chain in selecting feed rates and cutting speeds to generate certain chip forms, to extend tool life and minimise subsurface deformation for specific titanium alloys. Assessment of these key characteristics has provided an understanding of the effects of mechanical twinning on the poor chip control through increasing the accommodation of strain prior to fracture.

A transpressional model for deformation patterns in northern part of dezful Embayment's oil fields in Zagros (Iran), using geo-information technologies

The Dezful Embayment Zone (DEZ) is a discrete structural unit hosting predominant oil fields in the Zagros Mountains. The northern part of the DEZ has been studied using Geo-information Techniques (GiT) to ascertain the role of surface and subsurface deformation patterns forming traps for oil fields in the region. The surface structures and outcropped rock types were studied using remote sensing techniques and detailed field investigations. Also, the subsurface studies are consist of: a) preparation of iso-potential surface maps from underground contour (UGC) maps and their 3D-sketches; b) preparation of 3D-perspectives from field surveying data and 2D seismic studies; c) the compilation of three cross sections; and d) compilation of a basement and aeromagnetic maps. The results of the subsurface and surface investigations revealed that activity along subsurface NW-SE orientated thrust faults caused to folding of sedimentary cover as fault related folding and then, the accumulation of hydrocarbons were taken placed in these structures in DEZ. Movement along these faults resulted in the forming of a network of braided pattern of elliptical shaped anticlinal oilfields with structural blocks at different depths. Thus, the thrust faults controlled the position, elliptical form and elevation of anticlines in the northern part of the DEZ. Finally, a complex consecutive transpressiontranstensional model, due to a shear regime, is proposed for the deformation pattern in the region. Whereas, the structural pattern of the southern part of the DEZ is a simple discrete folding and coeval thrusts which forming anticlinal oil traps at similar depths.

Numerical analysis of subsurface deformation induced by groundwater level changes in the Bangkok aquifer system

Subsurface deformation due to long terms of groundwater drawdown from 1960 to 1997 and groundwater recovery from 1997 to 2016 in the upper part of the Bangkok multi-aquifer system and their possible effects on substructure stability were analyzed. The updated groundwater monitoring data show a linear recovery trend with a full recovery by 2031 in the study aquifer. Subsurface deformation was calculated using FEM transient coupled pore pressure/effective stress analysis by Abaqus. It was found that the groundwater drawdown from 1960 to 1997 caused a subsidence of 51, 62, and 76 cm, while the following groundwater recovery from 1997 to 2016 could pull back a rebound of 9.8, 9.7, and 5.3% at the three study sites, respectively. The effects of the change in pore pressure and undrained shear strength of the clay layers on the ultimate pile capacity were studied for cases of high-rise and low-rise buildings at a selected site. It was found that the groundwater drawdown from 1960 to 1997 could cause an increasing rate of ultimate pile capacity of about 1.0–1.5% per year, while the groundwater recovery from 1997 to 2031 can cause a similar reduction rate of ultimate pile capacity.

Tribological response of binary Mg-xZn (Where X = 1, 3 and 6 wt%) alloys

Abstract Magnesium alloys are one of the futuristic materials for many engineering applications. Once surface and subsurface related degradation issues are resolved, their use can be promoted in many applications. Present work explores the effect of Zn doping into Mg-Zn alloy during tribological interactions where surface and subsurface responses are important. Tribological studies are performed using tribometer. Polished, scratched and worn surfaces are analysed using optical microscope, scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS), respectively. Study reveals that addition of Zn improves the hardness, which controls the surface and sub-surface deformation. Some deformation mechanisms are corelated to amount of Zn doping.

On the differences in shear band characteristics between a binary Pd-Si metallic and nanoglass

Shear band morphology of a binary Pd80Si20 nanoglass (NG) and metallic glass (MG) was investigated using bonded interface indentation technique. The results clearly indicate that the plastic strain in the subsurface deformation zone in NG is accommodated by very fine secondary shear bands in addition to a fewer primary shear bands while in MG it is mainly by primary shear bands. Furthermore, at any given indentation load, the size of the normalized subsurface deformation zone, χ, is found to be higher for NG compared to MG suggesting that the deformation of Pd80Si20 NG is more pressure sensitive and softer than MG. These differences in deformation characteristics between the NG and MG closely related to the intrinsic differences in the glass structure.

Crustal structure of the metasedimentary Kisseynew domain and bounding volcanic–plutonic domains, Trans-Hudson orogen, Canada

The Kisseynew domain (KD) is the largest component of the Paleoproterozoic Trans-Hudson orogen (THO) in Saskatchewan and Manitoba. It is bounded to the north by the Lynn Lake – Leaf Rapids (LL-LR) domain and to the south by the Glennie – Flin Flon (G-FF) complex. The THO was the focus of one of the study areas of Lithoprobe, Canada’s national Earth science research project (1984–2005). To further investigate the crustal structure of the KD and its bounding domains, this study reprocesses reflection line S3a across its northern boundary, analyses four 2.5-D gravity profiles, carries out 3-D gravity inversions for two areas, and replicates results from reflection lines 7 and 10 across the southern boundary of the KD. The reprocessed seismic section enhances the continuity of reflections within the crust. The reflectivity is representative of the complex tectonic development of the boundary zone and clearly identifies a subsurface deformation zone consistent with the boundary. The reflection section also shows that a lower plate (at about 30 to 50 km depth), interpreted as remnant lower crust of the G-FF complex, extends 30 km further northward than in the original section. Lines 7 and 10 illustrate the complex nature of the transition from the KD to the G-FF complex. The gravity analyses show that the variability and complexities of the boundary region between the LL-LR domain and KD, and the G-FF complex and KD, as indicated by the geological and Bouguer gravity maps, extend at depth throughout the crust.

The Specific Features of the Geodynamic Settings in the Southeastern Part of the Magellan Seamounts, Pacific Ocean

Based on a detailed bathymetric map of the southeastern part of the Magellan Seamounts created using the results of multibeam echo sounding, a lineament analysis of the seafloor relief was performed, linear landforms were distinguished and their azimuths were measured, and a rose diagram was constructed showing the lineament direction in the area. Models of the deep and subsurface deformation fields of the area that identify blocks with predominant extension and compression stresses were constructed. The block motions occur along the lines of sign changes of the stresses (block boundaries). The directions of the block boundaries are compared with the lineament direction and a conclusion is made on their spatial and genetic relationship. The systems of directions of the linear landforms and the boundaries of deep and shallow blocks are partially consistent with four main systems of the global regmatic network, which indicates a significant influence of the latter on the structural plan of the area. The stress redistribution is related to modern geological processes that lead to the formation of new features of the seafloor relief and partial destruction of the old guyot surfaces.

Nanometric behaviour of monocrystalline silicon when single point diamond turned—a molecular dynamics and response surface methodology analysis

Hard and brittle materials such as silicon and silicon carbide are widely used in aerospace and integrated circuit. They are often poorly machined owing to non-linearity in machining process and complexities in selecting suitable machining parameters and tool geometry. The experimental difficulty involved in observing nanoscale physical phenomena (i.e. in-process measurement problems, inaccessible contact area of tool and workpiece, and the difficulty of surface analysis) has led to the use of molecular dynamics (MD) and response surface methodology (RSM) to investigate effect of tool edge radius, rake and clearance angles on monocrystalline silicon in this research. The response of subsurface deformation depth (SSD), tool temperature, kinetic friction cutting and thrust forces to tool edge radius, rake and clearance angles showed that SSD increased as the rake angle, edge radius and clearance angle increased while kinetic friction reduced as they increased. The increase in SSD as the clearance angle increased as observed in this study can be associated to the interactive/combined influence of the effects of both edge radius and rake angle.

Laboratory Model Test of EPB Shield Tunneling in a Cobble-Rich Soil

Model tests and field measurements were carried out to study the mechanical behavior of cobble-rich soil in response to shield tunneling. In particular, an experimental investigation was carried out using a laboratory-scale model. The model used includes a miniature shield machine that can approximate real tunnel construction, replicating the in-situ methods of excavation and support. The surface settlement and subsurface deformation were analyzed, and these data were compared with predictions based on previous studies. The results confirm that the model tests can effectively simulate the principal operations of a real earth-pressure-balance machine. The observed surface settlement troughs in both the transverse and longitudinal directions were found to be narrower than in clay or sandy soils. With respect to subsurface deformation, the deformation zone width decreases almost linearly as a function of depth.

Photogrammetry Method for Fast and Accurate Measurement of Strata Movements and Deformations for Scale Physical Mining Simulations

Scale physical models, constructed according to the principle of similarity theory, have been widely used to simulate the mining disturbances to surrounding strata and to evaluate the effectiveness of implemented ground control techniques. This technique has also been used for studying mining-induced surface and subsurface subsidence. The movements of the observation points installed on the physical model at different mining stages are currently measured using total station which is time-consuming and inaccurate especially on small scale models. A photogrammetry-based measurement system has been developed. During a physical modeling process, photos of the model can be taken during the simulation process reducing survey time from hours to a few seconds. A program, Photogrammetry Analysis for Physical Modeling of Mine Subsidence Process (PAPMMSP), developed based on photogrammetric principle is used to quickly identify the installed observation points and accurately determine their coordinates. The measurement accuracy is well under submillimeter level—an ultra-important advantage as any measurement errors in coordinates are magnified by the model dimension scale (commonly 20 to 400). A physical modeling case of subsurface strata movements and deformations associated with longwall mining operations is presented in the paper to demonstrate the functions and capabilities of the developed photogrammetry program.

Micromachining of coarse-grained aluminum including crystallographic effects

This paper presents an experimental analysis of the effects of crystallographic anisotropy of the workpiece material when machining coarse-grained pure aluminum under varying cutting conditions. Orthogonal cutting experiments were conducted on an instrumented planning setup, and cutting forces and surface roughnesses were measured in a full-factorial experimental design. Cutting speed, uncut chip thickness (feed), and tool rake angle were varied at multiple levels. To determine the effect of subsurface deformation left by the previous tool passes, experiments were conducted both with and without cleanup cuts that reduce the surface deformation. The effect of crystallographic orientations and their interaction with cutting conditions on the specific cutting energy, the effective coefficient of friction, and the resulting surface roughness were analyzed through an analysis of variance approach. It was concluded that the crystallographic anisotropy has a strong effect in specific cutting energies, with up to 360% variation across different grains. Similarly, the roughness of the machined surface was seen to vary significantly (up to 831%) with the crystallographic orientations. On the other hand, the effective coefficient of friction was observed to be insensitive to the changes in crystallographic orientations. Lastly, a significant (up to 45%) difference in specific cutting energies was observed between the cases with and without cleanup cuts, indicating the strong presence and the influence of sub-surface deformation.

Shear wave velocity structure of the crust and upper mantle in Southeastern Tibet and its geodynamic implications

Southeastern Tibet, which has complex topography and strong tectonic activity, is an important area for studying the subsurface deformation of the Tibetan Plateau. Through the two-station method on 10-year teleseismic Rayleigh wave data from 132 permanent stations in the southeastern Tibetan Plateau, which incorporates ambient noise data, we obtain the interstation phase velocity dispersion data in the period range of 5–150 s. Then, we invert for the shear wave velocity of the crust and upper mantle through the direct 3-D inversion method. We find two low-velocity belts in the mid-lower crust. One belt is mainly in the SongPan-GangZi block and northwestern part of the Chuan-Dian diamond block, whereas the other belt is mainly in the Xiaojiang fault zone and its eastern part, the Yunnan-Guizhou Plateau. The low-velocity belt in the Xiaojiang fault zone is likely caused by plastic deformation or partial melting of felsic rocks due to crustal thickening. Moreover, the significant positive radial anisotropy (VSH>VSV) around the Xiaojiang fault zone further enhances the amplitude of low velocity anomaly in our VSV model. This crustal low-velocity zone also extends southward across the Red River fault and farther to northern Vietnam, which may be closely related to heat sources in the upper mantle. The two low-velocity belts are separated by a high-velocity zone near the Anninghe-Zemuhe fault system, which is exactly in the inner and intermediate zones of the Emeishan large igneous province (ELIP). We find an obvious high-velocity body situated in the crust of the inner zone of the ELIP, which may represent maficultramafic material that remained in the crust when the ELIP formed. In the upper mantle, there is a large-scale low-velocity anomaly in the Indochina and South China blocks south of the Red River fault. The low-velocity anomaly gradually extends northward along the Xiaojiang fault zone into the Yangtze Craton as depth increases. Through our velocity model, we think that southeastern Tibet is undergoing three different tectonic modes at the same time: (1) the upper crust is rigid, and as a result, the tectonic mode is mainly rigid block extrusion controlled by large strike-slip faults; (2) the viscoplastic materials in the middle-lower crust, separated by rigid materials related to the ELIP, migrate plastically southward under the control of the regional stress field and fault systems; and (3) the upper mantle south of the Red River fault is mainly controlled by large-scale asthenospheric upwelling and may be closely related to lithospheric delamination and the eastward subduction and retreat of the Indian plate beneath Burma.

The Influence of Adding Coarse Grain Phase on the Tribo-Wear Characteristics and Mechanical Properties of Ultra-Fine Grained Al-2Cu-B4C Trimodal Composite at Room Temperature

In this paper, it is intended to analyze the influence of coarse grain (CG) phase on mechanical properties and wear performance of Al–2Cu-4 wt% B4C trimodal composite. Trimodal ultra-fine grained (UFG) composites with 30 and 50 wt% aluminum coarse grains (4-66-30) and (4-46-50) were prepared using powder metallurgy and hot extrusion. Wear tests were conducted for normal loads of 20 and 50 N at a sliding velocity of 0.6 m/s at room temperature. Results revealed that there was a direct relationship between the CG content and the plastic deformation of worn subsurface. Moreover, by adding 50 wt% CG, wear rate reached to around 0.02 × 10−3 (mm3/m) and plastic deformation increased significantly. Investigations on the microstructure indicated that wear mechanisms of the trimodal samples were a combination of abrasive, adhesive, and delamination wear in the tribological layer.

High temperature wear behavior of refractory high entropy alloys based on 4-5-6 elemental palette

Refractory high entropy alloys (RHEAs) have recently attracted significant attention for structural applications because of their excellent high-temperature mechanical properties. However, there are few reports and limited understanding of their tribological behavior at elevated temperatures. Here, the sliding and reciprocating behavior of two newly developed RHEAs, namely HfTaTiVZr and TaTiVWZr, based on 4-5-6 elemental palette were investigated from 298 K to 723 K against Si3N4 counterface and compared with stainless steel. The steady state friction coefficient was in the range of 0.23–0.35, which are among the lowest values reported for RHEAs. The wear rates for HfTaTiVZr and TaTiVWZr were observed to be on the order of 10−4 mm3/N.m. With increasing temperature there was initially an increase in wear rate for the RHEAs up to the temperature of 423 K followed by decrease in wear rate with further increase in temperature. Detailed microscopic characterization of the wear tracks and the counterface showed a transition from abrasive to oxidative wear mechanism with increase in temperature with the formation of stable oxides and subsurface deformation in the contact region by shear mixing of the oxides.

Effect of deformed subsurface on the corrosion resistance of biomedical CoCrMo alloy in simulated physiological solution

In most cases, the microstructure of implants is stable and changeless after implanted into the body. However, the metallic joint replacements would be worn during patients’ movements. Their subsurface microstructures were deformed and changed. That may affect the corrosion resistance of the joint. Due to the complex surface situation on the worn joints, it was difficult to distinguish and evaluate the influence of the subsurface microstructure from surface roughness, wear debris, etc. In this study, a CoCrMo alloy used for artificial joints was treated by high-energy shot peening method to obtain a similar deformed surface to the worn joints, but without introducing other influencing factors. The corrosion rate of the deformed alloy which was treated for 4 h was down by 93.3% in the phosphate-buffered saline (PBS) solution compared with the untreated alloy. However, with the addition of bovine serum albumin (BSA) into PBS, the treated alloy showed the poorer corrosion resistance when its concentration was equal to or greater than 0.1 μmol L−1. The defects (grain boundaries and stacking faults), which were introduced into the alloy surface during peening process, could accelerate anodic dissolution, improve element diffusion and increase the number of active sites. These were beneficial for forming a more compact and thicker passive film which enhanced the corrosion resistance of the alloy. However, the deformation of subsurface could promote the adsorption of protein on the alloy surface. The adsorbed protein molecules would chelate with metallic ions and weaken the passive film.

Study on hole quality and surface quality of micro-drilling nickel-based single-crystal superalloy

Nickel-based single-crystal superalloy has no grain boundary. This makes the traditional cutting mechanism of shearing and slipping along grain boundary of polycrystalline material based on the theory of elastic–plastic deformation not suitable for drilling single-crystal parts. To achieve high-quality and low-damage micro-drilling of nickel-based single-crystal superalloy, the micro-drilling surface/subsurface quality of the (001) crystal plane of nickel-based single-crystal superalloy was studied in this paper. Firstly, the influence rules of the cutting speed (vs) and the feed rate (vw) on the micro-drilling hole size, surface morphology, surface roughness and subsurface damage depth were studied. Then, the micro-hardness on micro-drilling subsurface was analyzed. Finally, the subsurface recrystallization was explored. The results show that with the increase in vs, the hole diameter error and the surface roughness decrease, and the depth of subsurface plastic deformation layer decreases first and then increases; with the increase in vw, the error of hole diameter and the surface roughness increase, and the depth of the deformation layer decreases first and then increases. When vw > 0.33 μm/r, there are severe scratches on the surface of the hole wall, and the hole wall appears undulating stripes; white layer structure and severe plastic deformation layer appeared on the micro-drilling subsurface; the γ and γ’ phases' deformation is severe; the micro-hardness at the subsurface white layer is small, and the micro-hardness value at the plastic deformation zone is large; after the high-temperature treatment, γ phase dissolves on the subsurface of micro-drilling parts, and the cellular recrystallization and the complete recrystallization occur. The minimum thickness of recrystallization layer obtained is 1.43 μm at vs = 141 m/min and vw = 0.105 μm/r. This study provides a good guidance and reference for the machining of nickel-based single-crystal superalloy micro-hole parts.

Microstructural changes in CoCrFeMnNi under mild tribological load

The lack of a principle element in high-entropy alloys (HEA) leads to unique and unexpected material properties. Tribological loading of metallic materials often results in deformed subsurface layers. As the microstructure feedbacks with friction forces, the microstructural evolution is highly dynamic and complex. The concept of HEAs promises high solid solution strengthening, which might decrease these microstructural changes. Here, we experimentally investigated the deformation behavior of CoCrFeMnNi in a dry, reciprocating tribological contact under a mild normal load. After only a single stroke, a surprisingly thick subsurface deformation layer was observed. This layer is characterized by nanocrystalline grains, twins and bands of localized dislocation motion. Twinning was found to be decisive for the overall thickness of this layer, and twin formation within the stress field of the moving sphere is analyzed. The localization of dislocation activity, caused by planar slip, results in a grain rotation. Fragmentation of twins and dislocation rearrangement lead to a nanocrystalline layer underneath the worn surface. In addition, oxide-rich layers were found after several sliding cycles. These oxides intermix with the nanocrystalline layer due to material transfer to the counter body and re-deposition to the wear track. Having revealed these fundamental mechanisms, the evolution of such deformation layers in CoCrFeMnNi under a tribological load might lead to other HEAs with compositions and properties specifically tailored to tribological applications in the future.