3g Positions Research Articles

Design and manufacturing of Welded Vacuum Testing (WVT) tool

To ensure the quality of welded joints in the hull area, welding testing is very important and must be carried out. But unfortunately, currently the quality testing process of welded joints was still limited to penetrant tests and lime tests. The purpose of this study was to obtain a portable welding testing machine that was able to obtain fairly accurate test results on hull welding defects using a vacuum system. The research method is experimental by involving data collection through field experiments, testing is carried out with the resulting weld defect research subjects and the length of testing time on 1G and 3G position welding. The results of the study by compared tests among Welded Vacuum Testing (WVT) machines, Magnetic Particle tests (MP), and Penetrant Tests (PT). The three experiments detected leaking weld defects, spark sparks, pinholes, overlaps, and undercuts. For test results with machines made, welding defects that were successfully detected were leaks in the 1G position welding workpiece and undercut in the 3G position welding workpiece. Air bubbles at a vacuum pressure of 0.2 bar are detected, meaning that there is a defect in the welded joint. This tool can be used in bilge testing.

Comparisons of microstructure and mechanical properties of MAG joints welded under 2G and 3G conditions

MAG welding of 07MnMoVR steel was performed at the 2G and 3G positions, and weld formation, microstructure, residual stress, and tensile properties were compared. In this study, welds without defects were obtained at the 2G and 3G positions. The results showed that a larger distortion of the weld at the 3G position was present because of the higher heat input and that the perlage morphology was related to the introduction of the arc weaving process. In addition, the grain size of the filling pass was coarser than that of the cap pass because of the repeated heating process, and the grain sizes of the filling and cap passes increased by approximately 33% for the weld at the 3G position compared with that at the 2G position. In this case, the weld at the 3G position showed a larger residual stress and lower yield and tensile strengths, and the elongation rates and microhardness of the weld at the 3G position were lower than were those of the weld at the 2G position, regardless of the root pass, filling pass, or cap pass.

Magnetocaloric effect in spin-glass-like GdCu4Mn compound

Materials based on Gd with magnetic frustration may have high magnetocaloric application potential. GdCu4Mn crystallizes in hexagonal CaCu5-type structure with space group P6/mmm (no. 191, Pearson symbol: hP6). Lattice parameters for the polycrystalline sample are equal to a = 5.114(3) Å and c = 4.151(4)Å. Due to structural disorder, namely random distribution of Cu and Mn atoms on 2c and 3g positions, a spin-glass-like behavior is observed in this material at low temperatures. In addition to the standard measurements of DC magnetization and AC magnetic susceptibility, the spin-glass state was confirmed by the memory effect and relaxation behavior. The absence of clear anomalies in the temperature dependencies of specific heat and electrical resistance suggests the lack of long-range magnetic order. For a change in magnetic field from 0 to 5 T, maximum values of the isothermal magnetic entropy change (ΔSm), temperature averaged entropy change (TEC(5)), relative cooling power (RCP), and adiabatic temperature change (ΔTad) at ∼50 K are equal to −1.3(1) J/(kg K), 1.2(1) J/(kg K), 125(1) J/kg, and 0.5(1) K, respectively.

Analysis of Welding Position and Current on Mechanical Properties of A36 Steel using Shield Metal Arc Welding

Welding is an assembly process that is most often used in the world of construction today. Welding is often used for repairing and maintenance of all tools made of metal, both as a process for filling cracks, temporary joining, or cutting metal parts. This study aims to determine the effect of welding current and position on the tensile strength and Vickers hardness (HV). This study uses ASTM A36 steel plate as base material. The variation of welding currents used are 90A, 110A, and 130A combine with variations in positions 1G, 2G, and 3G. The electrode used in this study is E6013 electrode with a diameter of 3.2 with a butt joint connection. All of processes are performed in room temperature with a strict condition. The results are as follow, the highest Ultimate Tensile Strength is obtained at 90A current and 3G position with a value of 471.93 MPa. For the highest hardness in the Vickers test, it is also obtained at 90A current and 3G position with a value of 242.20 Kgf/mm2.

Analysis of quality student practice results in shielded metal arc welding

This study aims to describe and determine the breakdown level of the V Groove welding results of students in Shielded Metal Arc Welding practice in the 3G (Vertical Up) position based on the American Welding Society standards. This study uses a quantitative descriptive research approach to describe the quality of the welding results. The collecting data in this study uses a visual assessment checklist based on AWS standards. The research conduct in a fabrication workshop at, Department of Mechanical Engineering Education, Faculty of Engineering, Yogyakarta State University. The data analysis technique was done by visually assessing students’ welding results and averaging them then describing them. The number of samples from this study were all training participants totaling 18 students. The results of this study indicate that: overall, the pass rate of students in welding the V groove connection in the 3G position SMAW practice is still meager, from a total of 18 students, none of them passed. Most students did not pass welding in the irregular bead, free from arc stray and spatter, undercut material, weld profile, and crater cross-section. The cause of student failures is due to a lack of understanding of how to avoid welding defects.

Tuning the magneto-elastic transition of (Mn,Fe,V)2(P,Si) alloys to low magnetic field applications

The first-order magneto-elastic transition in the Mn–Fe–P–Si alloys can be tailored by vanadium substitution. Alloys with a suitable V substitution provide an excellent magnetocaloric effect with minor hysteresis in low magnetic fields up to 1.2 T. Mössbauer measurements show that the hyperfine field is reduced by V substitution. Neutron diffraction reveals that Fe is substituted by V on the 3f site and the magnetic moment on the 3f site is enhanced by the V substitution. The modified magnetic exchange field around the 3f and 3g positions in the lattice can be utilized to design suitable magnetocaloric materials that operate in low magnetic fields.

Modeling Self-Organization Processes in Crystal-Forming Systems: New Two-Layer Cluster–Precursor K44 = 0@8(Na2In6)@36(In6Cd6K6)2 for the Self-Assembly of the K23Na8Cd12In48–hP91 Crystal Structure

Using computer methods (the ToposPro software package), the combinatorial-topological analysis and modeling of the self-assembly of the K23Na8Cd12In48–hP91(a = b = 17.114 A, c = 10.442 A, group P6/mmm) crystal structure are carried out. The chemically different precursor clusters 0@8(Na2In6) and 0@K2In6 in the form of hexagonal bipyramids are established. The centers of Na2In6 clusters occupy positions 1a with a symmetry of 6/mmm. The centers of the K2In6–A and K2In6–B clusters occupy positions 2c with symmetry –6m2, and 3g positions with mmm symmetry. The Na2In6 clusters are the templates on the surface of which atomic shells of 36 atoms are formed. The composition of the two-layer cluster is K44 = 0@8(Na2In6)@36(In6Cd6K6)2. Layer formation occurs upon the K44 clusters binding to the K2Cd6–A clusters. The symmetry and topological code of the self-assembly of the 3D structures from the K44 suprapolyhedral precursors with the participation of the K2Cd6 polyhedral clusters, as well as Na and K spacer atoms, are reconstructed.

Investigation of Learning Model of Welding Practices in 3G SMAW Position Welder Competency Formation in Vocational High School

This study aims to: (1) uncover the learning model applied in 3G SMAW welder competence formation in SMK YP Gajah Mada Palembang and (2) determine the effectiveness of the applied learning model. This research is a descriptive study with interviews and documentation of data collection techniques. The results of the study are: (1) The learning model used to form 3G position welder competencies in students is a project-based learning model, (2) The learning model in SMK YP Gajah Mada Palembang has been effectively applied viewed from the percentage of pass students in competency test of expertise. In reverse, welding activities had not been effective to form 3G Position SMAW welding skills. The main instrument in welding practices is welding machine, meanwhile, SMK YP Gajah Mada Palembang only operates 4 welding machines that can be used with a ratio of 1 machine for 8 people. Consumables for 32 students per semester in welding practices are iron plate ± 100-150 kg, grinding blade 7-8 pieces/semester, electrodes ± 11-12 boxes/semester and time consumed for welding practices for entire 1 semester 17 times meetings with a total time of 98 hours or 4,410 minutes.

HSA800 강재의 FCAW 용접성, 용접자세 및 이음성능 연구

본 연구에서는 HSA800 60mm 강재의 FCAW 용접성, 용접자세 및 이음성능을 확인하기 위해 용접자세 1G와 3G에 대한 FCAW 공시체를 제작하여 10종의 시험을 실시하였다. FCAW 1G 및 3G의 시험결과는 HSA800 강재의 KS 및 강도의 균질성에 대한 기준을 만족하며, 양호한 용접부로 나타났다. 그러나 용접부 평판 인장시험결과 FCAW 3G의 경우 용접기술 및 방법의 개선이 필요하다고 판단된다. In this research, 10 specimens of FCAW welding with positions of 1G and 3G were tested to confirm the weldability, welding positions, and welded joint performance of 60mm HSA800 steel. The test results showed that FCAW 1G and 3G satisfied HSA800 steel's KS and the criteria for homogeneity of strength, indicating a good weld zones. However, according to the tensile test results of weld zone, 3G position FCAW welding requires improvement of welding techniques and methods.

Microstructure and Porosity of Laser-welded Dissimilar Material Joints of HR-2 and J75

Dissimilar laser welding of HR-2 and J75 has a wide range of applications in high-and low-temperature hydrogen storage. The porosity distributions of the welded joints were investigated at different line energies, penetration status, and welding positions (1G, 2G, and 3G). The effect of the welding position on the welding appearance was evident only at high line energies because of the essential effect of gravity of the larger and longer dwelling molten pool. The porosity of the welded joints between the solutionised and aged J75 and HR-2 at the 3G position and partial penetration was located at the weld centre line, while the porosity at the 2G position with full penetration was distributed at the weld edges, which is consistent with the distribution of floating slag. Full keyhole penetration resulted in minimum porosity, partial penetration resulted in moderate porosity, and periodic molten pool penetration resulted in maximum porosity.

Calculation of the electronic structure of the intermetallic compounds ErNi5 − x Al x (x = 0, 1, 2)

The evolution of the electronic structure of the intermetallic compounds ErNi5 − x Al x (x = 0, 1, 2) with different positions of the substitution of aluminum atoms for nickel atoms has been investigated. For this purpose, spin-polarized calculations of the energy band spectra of these compounds have been performed using the LSDA + U method, which in the local spin density approximation takes into account strong electron correlations in the 4f shell of the erbium ion. Variants of the substitution of aluminum atoms for nickel atoms in different crystallographic positions in the 3d sublattice have been considered. An analysis of the band structure has demonstrated that substitutional aluminum impurities lead to the formation of nonmagnetic nickel 3d states and to a significant decrease in the electron density of states at the Fermi level. A comparison of the total energies of the substitutional configurations has revealed that the occupation of the 3g positions by aluminum atoms is more energetically favorable.

Cobalt-related features of spectral and magnetic properties of RNi4Co (R=Ho, Er)

In this paper we investigate spectral and magnetic properties of RNi4Co (R=Ho, Er) intermetallics to reveal the features associated with the presence of Co substituting ion in comparison with the parent HoNi5 and ErNi5 compounds. Our ab initio LSDA+U calculations show that in the electronic structure Co states are strongly manifested near the Fermi energy for the case of Co in 2c position, while Co in 3g position results only in weak changes of the total DOS curve. Theoretical optical conductivity calculated assuming Co equally redistributed among 2c or 3g positions agrees well with the experimental optical conductivity. Cobalt ion in RNi4Co (R=Ho, Er) is characterized by magnetic moment of 1μB that increases exchange interaction in the 3d sublattice by several times that contributes to the growth of Curie temperature in comparison with the parent compounds.

Experimental Study for Structural Behavior of Embed Plate into Concrete Subjected to Welding Heat Input

In a super-tall building construction, thick and large-sized embed plates are usually used to connect mega structural steel members to RC core wall or columns by welding a gusset plate on the face of the embed plate with T-shape. A large amount of heat input accumulated by weld passes causes the plates to expand or deform. In addition, the temperature of concrete around the plates also could be increased. Consequently, cracks and spalls occur on the concrete surface. In this study, the effect of weld heat on embed plates and 80MPa high strength concrete is investigated by considering weld position (2G and 3G position), edge distance, concrete curing time, etc. Measured temperature of the embed plates was compared with the transient thermal analysis results. Finally, push-out tests were performed to verify and compare the shear studs capacity of the embed plate with design requirement. Test result shows that the shear capacity of the plate is reduced by 14%-19% due to the weld heat effect and increased as the concrete curing time is longer.

Effect of Plate Thickness and Weld Position on Distortion and Residual Stress of Welded Structural Steel

Residual stresses are generated as a result of non-uniform temperature distribution during welding and particularly cooling process during fabrication of the welded parts. Residual stresses have a major effect on the overall performance of a component in service. In this instant, the residual stress in the form of angular distortion is primarily caused by shrinkage on longitudinal and transversal direction. Several single v-butt joints on structural steel plates of SS400 are investigated by using different plate thickness and welding positions (1G and 3G). GMAW method was used in the welding process. Measurement of residual stress was carried out on a plate with the thickness of 16 mm on longitudinal, transversal and normal direction by using neutron diffraction method. Results showed that the angular distortion of the welded plates increase with the increase of plate thickness. Welding by vertical position (3G position) resulted in a bigger angular distortion compared to flat position (1G position). The distribution of residual stress varied between tension and compression residual stress along welded area with the range of -10 mm to 10 mm. Measurement of residual stress on the longitudinal direction has the greatest value among two other directions.

High magnetic field study of the anisotropy and neutron diffraction investigation of the crystal and magnetic structure of YCo 4.5Ge 0.5

The solubility limit of Ge in the YCo 5− x Ge x structure is shown to be close to one Ge atom per formula unit by combining diffraction techniques and electron microscopy. The evolution of the crystal structure of the YCo 4.5Ge 0.5 compound is studied by X-ray and neutron diffraction experiments. A preferential substitution scheme is observed, the Ge atom being preferentially located on the Co 3g positions. Powder neutron diffraction results shows that the Co magnetic moments are significantly reduced by the presence of Ge in the crystal structure. The intrinsic magnetic properties such as the saturation magnetization and the magnetocrystalline anisotropy parameters are determined at 4.2 and 300 K from a fit of the isothermal magnetization curves measured in applied field up to 23 T. Ge for Co substitution induces a reduction of the first order anisotropy parameter. The large magnetocrystalline anisotropy found for YCo 4.5Ge 0.5 is not much reduced upon heating from 4 to 300 K. The results are compared and commented in the light of that reported earlier for YCo 5 and other homologues such as YCo 4Al or YCo 4Ga.

Magnetism and phase stability of R(Co,M)7 pseudobinary intermetallics with TbCu7-type structure

Pseudobinary RCo7−xMx intermetallic compounds with TbCu7-type structure have been synthesized, and their structural and magnetic properties have been investigated using powder x-ray diffraction and magnetic measurements. Based upon the structural analysis, the stabilized element M occupies the 2e or the 3g position depending on its electronegativity. RCo7−xMx compounds exhibit ferromagnetic order with high Curie temperature. In addition, the uniaxial magnetocrystalline anisotropy is observed in SmCo7−xMx intermetallics. The magnetic moments have been investigated using a modified magnetic valence model with the equation ⟨Zm⟩=±xRZmR+xTZmT+2Nsp↑∑ixi, where the magnetic moment contributed by 4f transition metal is corrected from its chemical valence numbers of rare earth in the original magnetic valence model to the theoretical value of gJμBJ. It is also assumed that the nonmagnetic metal has no contribution to the moment. The corrected model can also be used to calculate the moments of the other strong ferromagnetic intermetallics such as R–(T,M) 1:5, 2:17, and R2Fe14B, etc. This model could estimate and even predict the moments as long as the composition of the ferromagnetic alloy is known.

Structures of the ζ and ζ′ phases in the Ag–Ga system

The crystal structures of the ζ-phase and ζ′-phase have been determined by X-ray powder diffraction and refined by Rietveld method. The space group of the ζ′-phase is P 6 ¯ 2 m with the lattice parameters a = 7.7710(1) and c = 2.8788(1) Å. The ideal formula is Ag 2Ga (real composition Ag 2+ x Ga 1− x , x = 0.16) and the chemical formula per unit cell is Z = 3. Six Ag atoms occupy the 3g positions with x = 0.63970(8) and the 3f positions with x = 0.30347(9), respectively. Three Ga atoms occupy the 2c and the 1b sites. The ζ-phase is obtained by quenching the sample containing 20 at.% Ga from 500 °C to room temperature. Its space group is close-packed hexagonal, P6 3/ mmc, and the lattice parameters are a = 2.8818(1) and c = 4.6956(1) Å. There are 2 atoms (1.5Ag + 0.5Ga) per unit cell, which occupy the 2c site statistically. The relation between the structures of the ζ- and ζ′-phase is discussed.

Effect of Al Substitution on the Electronic and Magnetic Properties of GdCo5

Experimental data show that aluminium doped RCo 5 systems crystallize in CaCu 5 -type structure for most of the rare-earth elements (R). Al impurities randomly occupy one of the two possible positions (2c and 3g) and thereis a critical concentration of Al, x c = 2.0, for RCo 5 - x Al x when the Co sublattice becomes nonmagnetic. The ab initio self-consistent calculations show strong dependence of magnetic properties of GdCo 5 - x Al x on concentration of Al and position of the impurities in the unit cell, furthermore to fulfil experimental observation of existence of critical concentration, x c = 2.0, the Al impurities should prefer 3g positions otherwise the magnetic moments on Co atoms do not vanish.

The electronic and electrochemical properties of the LaNi 5, LaNi 4Al and LaNi 3AlCo systems

Nanocrystalline LaNi 5-type materials have been prepared by mechanical alloying (MA) followed by annealing. The amorphous phase forms directly from the starting mixture of elements, without formation of other phases. The LaNi 5, LaNi 4Al and LaNi 3AlCo systems crystallize in the hexagonal CaCu 5 type structure ( P6/mmm). The electrochemical properties of these type of materials, in which there has been a partial substitution of Ni by Al and Al–Co, have been investigated and discharge capacity enhancement has been observed. The electronic structure has been studied by the tight binding version of the linear muffin-tin orbital method in the atomic sphere approximation (TB-LMTO ASA). Total energy calculations showed that the Al and Co impurities prefer 3g positions.

Crystal structure determination of Ag2Ga by single crystal X-ray diffraction

Abstract The crystal structure of ζ′-Ag2Ga has been determined by single crystal X-ray diffraction at 293 K and 150 K. The structure is hexagonal with the non-centrosymmetric space group P[unk]2m (no. 189). The cell dimensions are a = 0.77680(16) nm, c = 0.28759(6) nm at 293 K and a = 0.77460(16) nm, c = 0.28704(5) nm at 150 K. ζ′-Ag2Ga has the InMg2 type of structure with nine atoms (six Ag and three Ga) on four different atomic sites (3f, 3g, lb and 2c). The Ag atoms fully occupy the 3f and 3g positions and the Ga atoms the lb and 2c positions. The structure parameters (atomic positions and anisotropic thermal parameters) were refined using data collected on a Siemens SMART CCD SYSTEM. The composition of the single crystals was determined by Energy Dispersive X-ray Spectroscopy (EDS) in a Scanning Electron Microscope (SEM).