Dilatometric Tests Research Articles

Study of Anisotropy Characteristics of Bogor Volcanic Soil

Anisotropy in soil results from the deposition process which describes the characteristics of the soil grains or is caused by stress or from the consequences of stresses caused during deposition and subsequent erosion. All soils behave in general anisotropy and some exhibit undrained shear strength. This study conducted 2 tests, namely the first field testing with original soil samples in the form of CPTu and dilatometer. The CPTu test's objective is to determine the vertical soil parameters, while the dilatometer is to determine the horizontal soil parameters. This study indicates that the indication of anisotropy in all shear strength tests is evident in the results of the CPTu test and the Dilatometer test. TX - UU and consolidation show that the horizontal shear strength (Suh) is greater than the vertical slope shear strength (Suv). In this case, the ratio obtained for shear strength is Suh = 1.3 Suv. And from the results of the consolidation test in the laboratory, it was found that the horizontal compression index parameter (Cc horizontal) was greater than the vertical (Cc vertical) and the horizontal coefficient of consolidation (Ch) is greater than the vertical coefficient of consolidation (Cv).

Dynamic compaction of the Baltic basin silty Sand - quality assurance with CPT, DPM, DMT and PLT

Post-glacial evolution of the Baltic basin sedimented Quaternary soils at the great thickness (up to 30 m) in Riga, Latvia. There are present zones of different combinations of postglacial, alluvial, limnological and dune formations within the metropolitan area of Riga. The geomorphological evolution of this territory is dominated by the Baltic sea former stages, distinguishing these areas as rather complicated. The dynamic compaction was proposed below the warehouse floor of area about 40K m2 in Baltic basin silty Sand. The effect of compaction was evaluated to the depth of 10 m and extensive quality assurance using cone penetration and piezocone tests (CPT(U)), dynamic probing (DP) tests, flat dilatometer tests (DMT) and plate loading tests (PLT), was introduced. CPT(U) and DMT results were compared in terms of soil stiffness parameter evaluation prior and after dynamic compaction. The limitation of DP tests were investigated and finally also warehouse test embankment verified by PLT evaluating shallow compaction rates.

Prediction of Postflotation Tailings Behavior in a Large Storage Facility

Extracting and copper production on a large scale generates large volumes of postflotation mine tailings. The scale of operation and development of tailings storage facilities (TSFs) forces the use of innovative solutions enabling safe storage now and in the future. Any changes to the operation require multi-directional monitoring of the impact of these changes on storage safety. The ongoing exploitation will be ensured by expansion of the TSF and a change in tailings storage technology. This approach will preclude the need for changes to the new location, such as changes of land use, and will minimise the volume of mine waste. The paper presents the results of pilot studies carried out to implement the change in postflotation tailings storage technology at Żelazny Most TSF (Poland) in the future. The aim of the paper was settlements prediction of tailings and comparison of deformations with observed settlements. Settlements prediction of tailings was made on the basis of the results of the DMT (Marchetti Dilatometer Test), recommended for the prediction of natural soil settlement. Depending on the analysed zone of the TSF, settlements ranged from a few centimetres to over 1.5 m. Despite the difference shown, the results of DMT and geodetic measurements indicate a convergent trend of settlement.

Heat treatment effects on the hardness and wear behavior of laser-welded AISI40 martensitic steel plates

The use of laser beams for joining materials has grown along with the need to weld more challenging materials such as martensitic steels. In this work, an AISI 420 martensitic steel plate was autogeneously welded using a fiber laser. The process parameters were 2000 W power and weld speed of 16 mm/s with the focus on the plate surface. Before welding, the plates were prepared in two conditions, tempered, or annealed, and tempering was performed at temperatures of 300°C, 400°C, 500°C, and 700°C after welding. The finite element analysis and dilatometric tests allowed to determine the phase transformations of this steel under development by the company Aperam. The observed microstructure varies according to the initial state of the plate and subsequent heat treatments. The hardness of the fusion and heat-affected zones varied according to the samples. The welded sample in the tempered state softened moderately due to the reheating of the laser beam. In the case of the annealed sample, the hardness of the molten zone was the highest obtained. This high hardness was reflected by a high resistance to wear by reciprocal sliding in the annealed case, compared to the other conditions. The fusion zone generally proved to be much more resistant to wear than the base material.

The fiber spinnability and mixed alkaline effect for calcium magnesium aluminosilicate glasses

In this paper, we discussed the fiber spinnability and mixed alkaline earth effect in the aluminosilicate glasses with MgO replaced by CaO. The high-temperature viscosity, dilatometric and DSC tests were applied. Results show that Kfib shows the opposite results to that from the graphical map of (m:D), while the ΔT only picks one glass sample for fiberizing. The mixed alkaline earth effect manifests itself as minima in viscosity, and characteristic temperatures, but maxima in fragility, thermal expansion, which are related to the increased entropy, the loose network, and weak bonds, not the network connectivity. The lower values for Mg end-member would be attributed to the higher field strength that would attract the nearest oxygen and cause more disturbance to the glass structure. The free volume is not related to the mixed effects in the viscosity and characteristic temperatures but should have a relationship with the melt strength index.

Study of rail steel alloying by chrome and vanadium effect on dissociation of overcooled austenite

To determine weldability and quality of a rail welded joint, information on kinetics of the rail steel overcooled austenite transformation is high importance. Thermo-kinetic diagrams of overcooled austenite dissociation of steels Э76ХФ, Э76ХАФ and Э76Ф, built based on results of dilatometric, metal science and durometric tests of rail steel samples. It was shown, that increase of chrome content in steels Э76Ф and Э76ХФ composition from 0.09 to 0.39% results in expanding of dissociation area of overcooled austenite at temperature scale for ferrite-cementite mixture and increasing of resistivity of the overcooled austenite against dissociation in the area of ferrite-cementite mixture formation. This can be characterized as decrease of critical quenching velocity from 100 to 30 °С/sec. It enables to obtain structural states of higher hardness at cooling with velocities in the area of 0.1−30 °С/sec. It was established, that increase of vanadium content from 0.04 to 0.07% does not cause quality changes at the thermo-kinetic diagram of overcooled austenite dissociation. However, it known, that vanadium is a strong carbide-formation element, which combines with carbon at low cooling velocities and removes it out of the solid solution. Due to this effect, sample of steel Э76ХФ with lower vanadium content at cooling with velocities from 0.1 to 10 °С/sec, had somewhat higher hardness level comparing with steel Э76ХАФ sample. Increase of chrome content in alloy content results in an increase of temperature of austenite formation completion at heating from 760 to 774 °С, while the temperature of martensitic transformation commencement at that remains practically unchanged at the level of 230 °С. In steels Э76ХФ and Э76ХАФ in the chemistry of which chrome was added in the amount of 0.37−0.39%, after cooling with velocities of 1 °С/sec and lower, apart from ferrite-carbide mixture of perlite type, formation of redundant ferrite with a volume share of 4−5% was observed as a result of overcooled austenite dissociation. However, in a steel Э76Ф sample, the content of which has chrome at the level of 0.09% at close content of carbon, after cooling in an analogue range of velocities, a ferritecarbide mixture of perlite type is formed with a slight trace of redundant ferrite in the structure as a result of overcooled austenite dissociation.

Assessment of the chemical composition of LTT fillers on residual stresses, microstructure, and mechanical properties of 410 AISI welded joints

The present paper aims to characterize the welding residual stresses, microstructure, and mechanical properties of some AISI 410 plates welded with low-transformation temperature (LTT) fillers containing different Ni wt.%. The LTT fillers with 11 wt.% Cr and Ni content varying between 3 and 11 wt.% were produced using an arc melting furnace. Effect of Ni wt.% on Ms of LTT fillers was studied using a dilatometer. Five-millimeter-thick AISI 410 plates were welded by GTAW using LTT fillers mentioned above and ER410 conventional filler as a reference. Welding residual stresses were measured by using the hole drilling strain gage method (HDSG). Analyzing the effect of welding dilution on the chemical composition of weld metal was carried out using energy-dispersive X-ray spectroscopy (EDS) followed by a dilatometric test for the evaluation of weld metals Ms after welding. Microstructural examinations show that conventional filler leads to ferritic–martensitic weld metal while in the cases welded with LTT fillers, delta ferrite (δ-ferrite) is decreased when Ni increases. Also, by increasing Ni more than 9 wt.%, the retained austenite is detected in the weld metal. Furthermore, weld metal hardness rises with increasing Ni. Performing tensile and impact tests on welded joints endorse the successful use of LTT fillers for welding the AISI 410 plates.

Poly(lactic acid) (PLA)/Poly(butylene succinate-co-adipate) (PBSA) Compatibilized Binary Biobased Blends: Melt Fluidity, Morphological, Thermo-Mechanical and Micromechanical Analysis.

In this work poly(lactic) acid (PLA)/poly(butylene succinate-co-adipate) (PBSA) biobased binary blends were investigated. PLA/PBSA mixtures with different compositions of PBSA (from 15 up to 40 wt.%) were produced by twin screw-extrusion. A first screening study was performed on these blends that were characterized from the melt fluidity, morphological and thermo-mechanical point of view. Starting from the obtained results, the effect of an epoxy oligomer (EO) (added at 2 wt.%) was further investigated. In this case a novel approach was introduced studying the micromechanical deformation processes by dilatometric uniaxial tensile tests, carried out with a videoextensometer. The characterization was then completed adopting the elasto-plastic fracture approach, by the measurement of the capability of the selected blends to absorb energy at a slow rate. The obtained results showed that EO acts as a good compatibilizer, improving the compatibility of the rubber phase into the PLA matrix. Dilatometric results showed different micromechanical responses for the 80–20 and 60–40 blends (probably linked to the different morphology). The 80–20 showed a cavitational behavior while the 60–40 a deviatoric one. It has been observed that while the addition of EO does not alter the micromechanical response of the 60–40 blend, it profoundly changes the response of the 80–20, that passed to a deviatoric behavior with the EO addition.

Effect of Heating Rate on Microstructure and Mechanical Properties in Al 7055

The effects of the heating rate during solid solution heat treatment on the mechanical properties and microstructure of the 7055 aluminum alloy were investigated. The dissolution and formation kinetics of the precipitates in the sample before the solid solution treatment vary depending on the heating rate. This is because the dissolution and formation of precipitate particles are diffusion-controlled. Therefore, dilatometric tests were carried out to control the heating rates during the solid solution treatment. Then, the mechanical properties were evaluated using hardness and compressive tests, while the microstructural features were observed using X-ray diffraction, optical microscopy, and scanning transmission electron microscopy. The characteristics of the precipitate for each heating rate were calculated using thermodynamic simulation, and a model to predict the mechanical properties was proposed based on the results.

Deformation modulus of rock foundation in Deriner Arch Dam

Civil engineering structures such as gravity concrete dams, arch dams, pressure tunnels, foundations of high-rise buildings and bridges are generally founded on rock. Design and performance of these structures are highly dependent on the deformation modulus of the rock mass so that expected deformations and/or differential settlements stay within the tolerable limits of the structures. In situ deformation modulus measurements of rock masses are generally performed by using the borehole dilatometer and plate loading tests in Turkey. The diameter of plate loading test device is 30-35 cm. Tests are performed in small unlined tunnels excavated in different elevations of dam abutments. The deformations upon loading are measured on the loading plate in the plate loading tests. It is not possible to exclude the effect of excavation disturbed zone since deformations are not measured with these devices. Large diameter plate test system may have multiple level extensometers set in drill holes opened perpendicular to loading plates. Reading from these extensometers may be utilized to exclude the effect of disturbed zone close to surface together with stress distribution estimated by using elastic theory. There are several field test methods for determining deformation modulus and each method has its own shortcomings. The optimum methodology to correlate plate loading test results with corresponding in-situ deformation modulus values is to back-calculate deformation modulus by using settlements measurements during the construction of dam body. In this paper, Deriner Arch Dam settlements measured during the construction are used to back calculate deformation modulus. It is found that in situ deformation modulus is about two times higher than the average value determined by plate loading tests. This finding will have important effects on the depth of foundation excavations, concrete layers to fortify structure foundations and the amount of consolidation grouting

Physical and Numerical Simulations of Closed Die Hot Forging and Heat Treatment of Forged Parts.

The paper describes physical and numerical simulations of a manufacturing process composed of hot forging and controlled cooling, which replace the conventional heat treatment technology. The objective was to investigate possibilities and limitations of the heat treatment with the use of the heat of forging. Three steels used to manufacture automotive parts were investigated. Experiments were composed of two sets of tests. The first were isothermal (TTT) and constant cooling rate (CCT) dilatometric tests, which supplied data for the identification of the numerical phase transformation model. The second was a physical simulation of the sequence forging-cooling on Gleeble 3800, which supplied data for the validation of the models. In the numerical part, a finite element (FE) thermal-mechanical code was combined with metallurgical models describing recrystallization and grain growth during forging and phase transformations during cooling. The FE model predicted distributions of the temperature and the austenite grain size in the forging, which were input data for further simulations of phase transformations during cooling. A modified JMAK equation was used to calculate the kinetics of transformation and volume fraction of microstructural constituents after cooling. Since the dilatometric tests were performed for various austenitization temperatures before cooling, it was possible to include austenite grain size as a variable in the model. An inverse algorithm developed by the authors was applied in the identification procedure. The model with optimal material parameters was used for simulations of hot forging and controlled cooling in one of the forging shops in Poland. Distributions of microstructural constituents in the forging after cooling were calculated. As a consequence, various cooling sequences during heat treatment could be analyzed and compared.

Effect of Hot Deformation on Phase Transformation Kinetics in Isothermally Annealed 3Mn-1.6Al Steel.

The kinetics of ferritic transformation and the corresponding microstructural evolution in 0.17C-3.1Mn-1.6Al-0.04Nb-0.22Mo-0.22Si medium-Mn steel during isothermal annealing was investigated in dilatometric studies. The material was subjected to thermal and thermo-mechanical treatments aimed at obtaining, by the austenite → ferrite transformation, a sufficient fraction of ferrite to stabilize the retained austenite by C and eventual Mn partitioning. The samples were isothermally held for 5 h in a temperature range from 600 to 750 °C to simulate simplified temperature conditions of an industrial coiling process following hot rolling. Some of the samples were plastically deformed at a temperature of 900 °C before isothermal holding in order to study the effect of hot deformation on the kinetics of phase transformations. After the dilatometric investigations the material was subjected to light and scanning electron microscopy to reveal relationships between the holding temperature, deformation and microstructure evolution. Hardness tests were performed to assess the mechanical behavior. A significant effect of manganese in slowing down diffusional transformations during the cooling of steel was found. The influence of austenite deformation on the kinetics of austenite to ferrite transformation was noted. The plastically deformed samples showed an accelerated start of ferritic transformation and the extension of its range. During dilatometric tests, low-range dynamic ferritic transformation was recorded, which was also confirmed by the microscopic tests.

Determination of Phase Transformation Temperatures by Dilatometric Test of S960MC Steel

Determination of Phase Transformation Temperatures by Dilatometric Test of S960MC Steel

Negative thermal expansion property of Eu0.8Sr0·2MnO3-δ

We firstly synthesized the novel negative thermal expansion (NTE) material Eu0.8Sr0·2MnO3-δ with superior physical properties by solid state method. Apart from the NTE properties, the micro constitution and structure are also presented. It can be concluded from the analysis of XRD, SEM and the EDS that the dedicated material was composed of homogeneous polyhedral of Eu0.8Sr0·2MnO3-δ which occupies the characteristic structure of orthogonal perovskite. The thermal dilatometer test also presented a good performance on NTE property with the liner coefficient of thermal expansion (CTE) −14.0 ​× ​10−6 ​K−1 (298–873 ​K). Besides, we analyzed that the distortion effect (Jahn-Teller effect) and oxygen defects are both necessary conditions for this typical NTE property in terms of distortion of the structure of the perovskite by doping the Sr2+.

Influence of Alloying Elements on the Dynamic Recrystallization of 4 wt.-% Medium Manganese Steels.

The hot deformation behaviour of air-hardening martensitic forging steels (of type 1.5132) is presented. The newly developed steels are characterized through dilatometric tests as well as through microstructure analyses with LOM and SEM and hardness measurements. Additionally, the influence of alloying elements on the flow curves at high temperatures is discussed. It is demonstrated that the higher alloying content does not increase the equivalent stresses in comparison to the reference alloys and contrariwise reduces the offset for dynamic recrystallization at temperatures below 1100 . Furthermore, the effect of different alloying elements on the strain hardening behaviour during hot compression of 4 medium manganese steels is presented. It is shown that boron reduces the offset for dynamic recrystallization if present in solid solution, while the combined addition of titanium and niobium annihilates the solid drag effect on the prior austenite grain boundaries.

Effects of Austenitization Temperature and Pre-Deformation on CCT Diagrams of 23MnNiCrMo5-3 Steel.

The combined effect of deformation temperature and strain value on the continuous cooling transformation (CCT) diagram of low-alloy steel with 0.23% C, 1.17% Mn, 0.79% Ni, 0.44% Cr, and 0.22% Mo was studied. The deformation temperature (identical to the austenitization temperature) was in the range suitable for the wire rolling mill. The applied compressive deformation corresponded to the true strain values in an unusually wide range. Based on the dilatometric tests and metallographic analyses, a total of five different CCT diagrams were constructed. Pre-deformation corresponding to the true strain of 0.35 or even 1.0 had no clear effect on the austenite decomposition kinetics at the austenitization temperature of 880 °C. During the long-lasting cooling, recrystallization and probably coarsening of the new austenitic grains occurred, which almost eliminated the influence of pre-deformation on the temperatures of the diffusion-controlled phase transformations. Decreasing the deformation temperature to 830 °C led to the significant acceleration of the austenite → ferrite and austenite → pearlite transformations due to the applied strain of 1.0 only in the region of the cooling rate between 3 and 35 °C·s−1. The kinetics of the bainitic or martensitic transformation remained practically unaffected by the pre-deformation. The acceleration of the diffusion-controlled phase transformations resulted from the formation of an austenitic microstructure with a mean grain size of about 4 µm. As the analysis of the stress–strain curves showed, the grain refinement was carried out by dynamic and metadynamic recrystallization. At low cooling rates, the effect of plastic deformation on the kinetics of phase transformations was indistinct.

Rigidity of “Warsaw clay” from the Poznań Formation determined byin situtests

AbstractThe character of morphogenetic processes occurring within river valleys depends on the mechanical and hydrogeological properties of deposits that build up such landforms. In the case of the Polish Lowlands, a series of Pliocene clay lake sediments (so-called Poznań mottled clays) plays a special role. Their current locations and properties are associated with specific sedimentation conditions and glacitectonic deformations, which the soils have been subjected to many times in Pleistocene. Their presence in the lithological profile influences dynamics of slope processes in valleys’ escarpment zones and channel erosion stabilization. In this article, the “Warsaw clay” from the Poznań Series Formation is presented in comparison with other cohesive Quaternary sediments, which are mostly building neighboring outcrops. This article analyzes the Seismic Dilatometer (SDMT) results and a method of interpretation to determineIR, plasticity index, and liquid limit (LL) parameters. The undrained shear strengthSuwas determined based on the Cone Penetration Test (CPT), SDMT, and laboratory test results. Spatial variability of the strength and deformation parameters in the study area were determined using dilatometer test (SDMT) results. Finally, the nomogram chart is proposed to obtain the rigidity index (IR) of the preconsolidated Pliocene clays, depending on bothp0andp1pressures from SDMT and effective vertical stressσv0′{\sigma }_{\text{v0}}^{^{\prime} }and pore water pressureu0.

Shaft friction from the DMT and direct shear interface tests

The article presents preliminary attempt to create tri-linear transfer curves for describing pile behaviour under axial loading. Transfer curves would use the parameter measured in dilatometer test, particularly a constrained modulus MDMT. The proposed method is based on concrete rough and smooth interface tests performed in a direct shear apparatus. Based on the obtained mobilization curves, relationships were created between the parameters describing the slope of individual transfer curves and the MDMT modulus. The obtained correlations were used to estimate the capacity of the concrete screw pile subjected to the static load test in tension.

On the structural integrity of Fe-36Ni Invar alloy processed by selective laser melting

Specimens made from pre-alloyed Invar (Fe-36Ni) powder were fabricated by selective laser melting and stress-relief heat treated afterwards. A relative density of the fabricated parts of 99.6 % was determined by computed tomography. The microstructure and mechanical behavior under monotonic and particularly cyclic loading at ambient temperature were investigated. Results reveal a bimodal microstructure containing columnar and equiaxed grains with an average grain size of 75 μm and pronounced texture 〈001〉 || BD. The selective laser melted Invar is characterized by a homogeneous hardness distribution revealing no gradient with respect to the height of the fabricated parts. The mechanical response under monotonic tensile loading is characterized by a fairly ductile behavior. Total strain controlled low-cycle fatigue tests with varying strain amplitudes were performed. The cyclic deformation response is characterized by highly reproducible behavior in terms of stress amplitudes and number of cycles to failure. The corresponding half-life hysteresis loops reveal perfect Masing behavior. Post-mortem fractography revealed crack initiation in direct vicinity of the surfaces. The damage tolerance of Invar is found to be promoted by its high ductility. Finally, a low coefficient of thermal expansion, very similar to conventionally processed Invar, was shown by dilatometer tests in the temperature range of 0 °C–180 °C.

Characterization of Phase Transformations During Graded Thermo-Mechanical Processing of Press-Hardening Sheet Steel 22MnB5

Safety-relevant components in automobiles require materials that combine high strength with sufficient residual ductility and high-energy absorption. A graded thermo-mechanical treatment of the press-hardening steel 22MnB5 with graded microstructure can provide a material with such properties. Different austenitization temperatures, cooling and forming conditions within a sheet part lead to the development of microstructures with mixed phase compositions. To determine the resulting phase contents in such graded processed parts, a large number of dilatometric tests are usually required. With a non-contact characterization method, it is possible to detect local phase transformations on an inhomogeneously treated flat steel specimen. For press-hardening steel after heat treatment and thermo-mechanical processing, correlations between austenitization temperature, hot deformation strain, microstructure, and hardness are established.