Cast Bars Research Articles

Marginal Fit of Selective Laser Melting Cobalt-Chromium Bar Versus Cast Bar on Mandibular Edentulous Casts with Two Implants Supported Over Denture: An In vitro Study

Marginal Fit of Selective Laser Melting Cobalt-Chromium Bar Versus Cast Bar on Mandibular Edentulous Casts with Two Implants Supported Over Denture: An In vitro Study

Evaluation of patient satisfaction and maximum biting force of three differently constructed bars on two implants retaining mandibular overdenture - one year follow-up (a randomized controlled clinical trial)

BackgroundDifferent bar construction techniques will affect the bar passive fitness, which may induce stresses or strain on the implant and/or tightening screw and sequentially may affect the biting force and patient satisfaction.Aim of the studyThis clinical investigation assessed patient satisfaction and maximum biting force (MBF) using three differently constructed (conventional casting, milling, and 3D printing CAD/CAM techniques) cobalt-chromium (Co-Cr) bar-retained implants mandibular overdentures over a one-year period of follow-up.Materials and methodsThirty edentulous patients seeking for two implants bar-retained mandibular overdentures were randomly assigned into three groups as the following: Group I: 10 patients received a Co-Cr conventional casting bar, Group II: 10 patients received a Co-Cr CAD/CAM milled bar, and Group III: 10 patients received a Co-Cr CAD/CAM 3D-printed bar. All the bar groups were connected to two implants in the canine area bilaterally. Within the first two weeks following implant placement, patients received the definitive prosthesis. Patient satisfaction was evaluated by using the (OHIP-EDENT-19) questionnaire form after 6, and 12 months. Additionally, the maximum biting force was tested at after delivery, 3, 6, and 12 months for each group. The results were collected, tabulated, and statistically analyzed. Trial registration: This study was recorded on ClinicalTrials.gov retrospectively registered (ID: NCT06401187) on 30/04/2024.ResultsAfter one year follow up, regrading patient satisfaction the three groups showed no statistically significant difference. Although, the functional limitation domain was in favor of the milled bar. Regarding the maximum biting force, no statistically significant difference was found among three groups. However, at 12 mouths follow-up the milled bar showed statistically value.ConclusionWithin the limitations of this study, the conventional, milled and 3D printed bar overdentures groups can be used as a satisfactory treatment modality for edentulous mandible in terms of patient satisfaction and maximum biting force.

Effect of cooling rate and Nb addition on the strengthening in eutectic CoCr1.3FeMnNi0.7Nbx (0 ≤ x ≤ 0.45) high entropy alloys comprising of low stacking fault energy FCC phase

The CoCr1.3FeNi0.7MnNbx (0.3 ≤ x ≤ 0.45) eutectic high entropy alloy (EHEA) comprising of ultrafine lamellae of low stacking fault energy (SFE = 11 mJ/m2) face centered cubic (FCC) and Laves phase are synthesized at cooling rates of 2.5–10 K/s (arc melted ingots, AMIs) and 4.2 × 102 K/s (suction cast bars, SCBs). The microstructural investigation suggests that secondary dendritic arm spacing (SDAS) and interlamellar spacing are refined in SCBs due to a higher cooling rate than the AMIs. Whereas, deformation twins evolve in FCC phase due to its low SFE. The EHEAs exhibit a high yield strength of 1327 MPa for x = 0.367 SCB and a large fracture strain of 20% for x = 0.3 AMI under compression. Systematic investigation on the influence of Nb addition, microstructure refinement, and evolution of deformation twins during straining on the strengthening mechanisms reveals that the phase interface strengthening, solid solution strengthening, and twin boundary strengthening play critical roles in providing the high flow stress. The post-deformation analysis and the presence of multiple positive slopes in work hardening curves confirms that the concurrent effect of the evolution of dislocations, deformation twins, and their mutual interactions are solely responsible for the severe strain hardening at multiple stages during plastic deformation. The low values of strain rate sensitivity (0.0106–0.0111) and the activation volume (28b3-41b3) suggest that the deformation kinetics is governed by the dislocation interactions with the ultrafine lamellae interface and twin boundaries.

Characterization of a functionally graded directionally solidified Al-33Cu alloy

To produce a functionally graded and directionally solidified (FGDS) structure, an Al-33Cu eutectic alloy has been centrifugally cast into a bar-shaped steel mold using a vacuum centrifugal casting system. Uni-dimensional cooling was performed to obtain directional solidification. Microstructural characterizations were carried out on the longitudinally sectioned cast bar along the solidification direction. Results showed that the Al2Cu eutectic lamellar spacing varied between 0.32 µm and 1 µm from the outer region to the inner region of the cast bars along a 75 mm distance. Centrifugal casting has resulted in microsegregation of copper concentration in a range between 55.8 % and 53.9 % from the outer region to the inner region, respectively. Similarly, the volume fraction of the Al2Cu eutectic has also varied between 45.3 % and 53.7 %. This leads to a significant variation in the hardness of the FGDS Al-33Cu eutectic alloy from 183 HB to 155 HB from the outer region towards the inner region.

Evolution Behavior of Rapidly Solidified Microstructure of a Ti-48Al-3Nb-1.5Ta Alloy Powder during Hot Isostatic Pressing

In this study, Ti-48Al-3Nb-1.5Ta powders were manufactured from cast bars by the supreme-speed plasma rotating electrode process (SS-PREP) and used to prepare hot isostatically pressed (HIPed) material at 1050–1260 °C with 150 MPa for 4 h. The phase, microstructure and mechanical performance were analyzed by XRD, SEM, electrical universal material testing machine and other methods. The results revealed that the phase constitution changed from γ phase to α2 phase and then to γ phase with the material changing from as-cast to powders and then to as-HIPed. Compared with the as-cast material, the grain size and element segregation were significantly reduced for both powders and as-HIPed. When the hot isostatic pressing (HIP) temperature was low, the genetic characteristics of the powder microstructure were evident. With the HIP temperature increasing, the homogeneity of the composition and microstructure increased, and the prior particle boundaries (PPBs) gradually disappeared. The elastic moduli of powder and as-HIPed were superior to those of as-cast, which increased with the HIP temperature increasing. The hardness of as-HIPed was lower than that of the powder. The compressive strength, compressive strain, bending strength, and tensile strength of as-HIPed were higher than those of as-cast. With an increase in the HIP temperature, the compressive strength decreased gradually, and the compressive strain first decreased and then increased.

A study of high cycle fatigue life and its correlation with microstructural parameters in IN713C nickel-based superalloy

IN713C nickel-based superalloy is widely used in the form of turbine blades in the automobile industry. High cycle fatigue (HCF) or very-HCF is one of the major failure modes for the alloy. The significant grain structure/size variations produced during the casting process are supposed to affect its fatigue life. In the present study, IN713C cast bars with different grain structures and grain size were HCF tested under similar stress level (∼300 MPa) at 650 °C. The fatigue life, varying from ∼87,000 to 10 × 106 cycles, mainly determined by the size of porosity and faceting grain. Size of porosity determines the time of initiation of faceting and crack, i.e., the crack initiation stage, which occupies the major part of fatigue life. Smaller pore size leads to delay of faceting and higher fatigue life. Whilst size of facet has profound effects in the crack propagation stage. Smaller facet (grain) size leads to lower crack propagation rate and longer loading cycles, and finally contributes to higher fatigue life. This research revealed the beneficial effect of smaller grain size on fatigue property from the perspective of reducing initial crack propagation rate, which has rarely been reported before.

PENETAPAN KLASIFIKASI TARIF POS KOMODITAS EMAS BATANGAN (GOLD CAST BAR) KE DAERAH PABEAN INDONESIA

ABSTRACT:
 Import Declaration containing the classification of HS code for goods is carried out by self-assessment which is then examined and determined by Customs and Excise in the event that the postal rate differs from the determination of Customs and Excise. The stipulation of Customs and Excise on the import of gold cast bars has caused a polemic because the validity is doubtful. This study aims to conduct a confirmatory academic review in order to obtain the correct classification of import Gold Cast Bar to the Indonesian Customs Region based on the principles of objectivity and freedom of opinion as well as so that it can be used as a guide for those in need. This research uses descriptive qualitative method design through literature study and interviews. Determination of tariff classification begins with the identification of goods and provisions for classification that have been uniformly determined by the WCO (World Customs Organization), the suitability of steps and approaches in determining tariff classification creates legal certainty and reduces prolonged polemics.
 Keywords: self assessment, tariff classification polemic, gold cast bar

Top cast effect: Influence of bond length on splitting mode failure

AbstractIt is widely considered that bond strength of bars cast near the top of a pour is weaker than that of bars cast near the bottom. The lesser strength of top cast bars is attributed to: (a)The increase in binder/cement ratio toward the top of a pour due to consolidation of fluid concrete prior to setting. (b)The formation of voids beneath bars as solids in fluid and setting concrete consolidate when the bar is restrained from vertical movement. The difference in bond strength bars cast near the top of a pour and those cast near the bottom varies widely between individual studies, with little difference reported in some studies and reductions in excess of 50% reported in others. A markedly greater top bar effect observed in pullout type specimens with short bond lengths compared to that in studies based on conditions more representative of practical construction. Through a simple analytical model of behavior of a lapped joint based on the local bond slip model in fib Model Code 2010, it is shown that the casting position effect diminishes as bond length increases. This influence is supported by analysis of trends in the top cast section of the ACI408 bond test database. Conclusions demonstrate the casting position factor in current design Codes significantly overestimates the top cast effect and justifies a casting position factor of 1.0 for laps designed to develop the full design strength of Grade 500 bars. Increased bond lengths would still be required for top cast laps designed for lower bar stresses.

Performance analysis of centrifugal-cast single-point cutting-tools developed from scrapped tools

ABSTRACT Single-point cutting tools were developed adopting a novel technique involving centrifugal casting using scrapped and discarded tools without any compositional adjustments. These tools included single-point cutting tools, drills, milling cutters, etc., and were melted in an induction furnace and cast in a vertical rotating mold. Single-point cutting tools were developed from these cast bars. The cutting ability of these developed tools was compared with that of conventional high-speed steel (HSS) tools that were procured from the market, for cutting of mild steel (A36) workpiece under identical tool geometry and cutting parameters. The cutting ability of the conventional HSS tool and the developed tool was observed to be comparable in terms of tool wear. Further, the surface-finish, force required for cutting and chip-configuration were more or less identical. The performance of the developed tool is comparable with the conventional cast HSS tool within the cutting velocity of 52.77 m/min and yields the most encouraging results, putting these tools at par with those available in the market. Thus, the novel technique adopted is claimed to be a viable method for developing single-point cutting tools without going for stringent methods of compositional adjustments and the costly forging methods for compaction.

Introduction to the Novel Plate for Manufacturing Thermomechanical Pulp

Refiner plates for manufacturing thermomechanical pulp (TMP) exhibit heavy and blunt-bar edges because they are manufactured via casting. Thus, replacing a cast plate that has exhausted its service life is time-consuming and a large amount of energy is required to reach the target freeness. To overcome the limitations of conventional cast plates for manufacturing TMP and chemi-TMP (CTMP), new dissimilar metal-joining technology was applied to lighten the TMP plate. A lightweight aluminum alloy was used as the base of the plate, and stainless steel alloy exhibiting excellent wear resistance was used as the bars. The lightweight plate, which was manufactured by inserting the bars into the base plate, can reduce the weight of the plate by up to a quarter compared with the cast plate. The refining performance of the lightweight plate was also similar or better than those of the cast plate. Particularly, the target freeness can be reached faster because the bar edge of the lightweight plate of a vertical bar shape was sharper than those of cast bars with a draft angle. This lightweight TMP plate obtained better results than the cast plates regarding the raw material throughput, shives content, and strength property development. However, the brightness of TMP and CTMP in the lightweight plate were slightly lower compared with those in the cast plate.

Mechanical modification of softwood pulp fibers using a novel lightweight vertical bar plate

Refiner plates made using sand casting have a draft angle, which results in a trapezoidal bar shape. These trapezoidal bar plates have a limited throughput compared to the vertical bar plates, and eventually the edges of the bars become dull, resulting in longer time to reach the target freeness and shorter service life. The new light-weight refiner plate with a bar insertion method into a plate base was developed by selecting an aluminium-based alloy as the plate base material and a stainless steel alloy with high wear resistance as the bar material. The light-weight plate with sharp bar edges was very effective in reducing refining energy by reaching the target freeness faster than the sand-cast bar plate. Finally, the lightweight sharp bar plate, which weighed only about half the weight of the cast bar plate, was expected to significantly contribute to easy replacement, improved paper quality, and larger throughput without excessive loss of fiber length.

Control of the chemical composition of heat-resistant nickel alloys upon manufacturing products from these alloys using additive technologies

Heat-resistant alloys (superalloys) widely used for manufacturing parts of various components of aircraft engines are complex nickel-based systems which contain apart from alloying (Al, Cr, Co, Ti, Mo, W, etc.) and microalloying additives (B, Mg, REM, etc.) different amounts of the impurities (Mn, Fe, Si, Pb, As, Sn), including gas-forming (O, N, C, S) ones. The use of additive technologies (AT) in manufacturing of complex-shaped parts made of these alloys makes it possible to increase the material utilization coefficient and shorten the technological process. However, the use of AT requires real-time control of the composition of semi-products and finished products at all stages of production. Study of various stages of manufacturing parts from ZhS6K and VZh159 alloys using an AT of selective laser alloying (SLA) is carried out using analytical control systems of the laboratory of the Testing Center (TC) of FSUE «VIAM». A complex of methods for atomic emission, mass spectrometric and X-ray fluorescence determination of different groups of elements was used for the analysis of charge materials, cast bar blanks, metal-powder compositions (MPC) and synthesized parts. The results of analysis of nickel N-1u and chromium Kh99N1 used upon and after smelting of cast billets, as well as analysis of MPC of these alloys carried out by different methods are presented (gas analyzers were used to determine the gas-forming impurities). Monitoring on the chemical composition of materials throughout the process of additive manufacturing ensure their compliance with the regulatory requirements and predict the properties of finished products. The work was carried out within the framework of complex scientific direction 2.1 «Fundamental research» («Strategic directions for the development of materials and technologies for their processing for the period up to 2030»).

Experimental and Numerical Analysis of Microstructure and High-Temperature Tensile Behavior of a Directionally Solidified Superalloy

A comprehensive cellular automaton algorithm coupled with finite element method was developed for the simulation of temperature field, heat transfer characteristics and the anisotropic grain growth during a directional solidification (DS) process. Nucleation parameters at the interface of the alloy and the chill plate were adjusted at four levels, and the evolution of macrostructure during competitive growth of grains has been characterized. The sensitivity of grain structure to heat transfer coefficients between alloy/chill plate and alloy/ceramic mold was also evaluated at a constant nucleation condition. The results were compared with the microscopic images and measurements of the experimentally cast DS specimens. This model was then utilized for the development of another micro-mechanical finite element model of the cast bars including the realistic grain boundaries and misorientations. To complete a simulation of a whole manufacturing chain from casting process to mechanical behavior evaluation, high-temperature tensile behavior of the cast bars was then elucidated through experiment and FE analysis.

Modeling the Process of Obtaining Bars from Aluminum Alloy 01417 by Combined Rolling-Extruding Method with Application of the Deform-3D Complex

The results of computer simulation of the process of combined rolling-extruding of longish deformed semi-finished products from alloy 01417 are presented. A feature of the research is that continuously cast bars with a diameter of 12.5 mm obtained using an electromagnetic mold are used as a workpiece. This makes it possible to increase the manufacturability of processing and to obtain after rolling-extruding billets for drawing with a diameter of 5 mm with a large resource of plastic and strength properties. For this case the technological parameters and temperature and speed conditions of combined processing have not yet been studied, therefore, their analysis was performed using the Deform-3D software package. It has been revealed that the feasibility of the rolling-extruding process is significantly affected by the frequency of rotation of the rolls. Moreover, the process becomes unstable when the value of this parameter is 4 rpm, which can be explained by insufficient degrees of deformation during rolling, and consequently by the small value of the active friction forces acting on the contact surface of the metal with the rolls. As a result of this, the processing temperature conditions also change, which is also demonstrated using the developed computer model. As a result, it was found that for the stable course of the combined rolling-extruding process at the CRE-200 unit of a continuously cast billet with a diameter of 12.5 mm from alloy 01417 at a heating temperature of the billet of 550 °C and a tool of 200 °C, degree of deformation during rolling 44% and drawing ratio during extruding 18.6 the frequency of rotation of the rolls should be at least 8 rpm. The simulation data used during the implementation of the process at the combined processing unit CRE-200, the results of which made it possible to finally obtain electrotechnical wire with a diameter of 0.5 mm from 01417 alloy that meets the requirements of TS 1-809-63-2018.

Critical assessment of CuZn39Pb2 processing maps

Abstract Isothermal hot compression tests of the CuZn39Pb2 continuous casting bar were carried out at 650 - 750 °C and strain rates of 0.1 - 50 s-1. After the experimental data were obtained, processing maps were constructed and discussed on the basis of the Prasad, Murty and Malas instability criteria to critically evaluate the flow behavior of the CuZn39Pb2 continuous casting bar. The microstructure suggested that the processing map based on the Murty instability criterion was suitable for optimizing the process parameters of the CuZn39Pb2. The relationships between the characteristics of processing maps and the deformation mechanisms under different strains were analyzed on the basis of Murty instability criterion. Considering the theoretical analysis results and energy consumption economy, 690 °C ≤ T ≤ 720 °C with 1 s-1 ≤ έ ≤ 3 s-1 are the best process parameters for CuZn39Pb2 forging.

Investigation of Plastic Properties of Ø8 Rod Made of Fire-Refined Copper of Kmor Grade

Results of the comparative ductility evaluation of Ø8 rods made of copper of the KM and KMor grades are discussed. It has been found out that plastic properties of KM and KMor grade rods at room temperature practically do not differ in their specific elongation and after-fracture contraction indices. At the same time, the ductility indices of KMor rod at temperature +850 °С became, practically, half-values. Increased spread of physical property values particularly the specific ohmic resistance of the rod KMor can be explained by the cumulative effect of variations of the chemical metal composition, and changes in process variables of the process (for example, unstable density of a cast bar), that initiate an occurrence of tension stresses during rolling. Calculation data of the limiting drawing ratio μr demonstrated that its value must not exceed 1.475.

Critical assessment of CuZn39Pb2 processing maps

Abstract Isothermal hot compression tests of the CuZn39Pb2 continuous casting bar were carried out at 650 - 750 °C and strain rates of 0.1 - 50 s-1. After the experimental data were obtained, processing maps were constructed and discussed on the basis of the Prasad, Murty and Malas instability criteria to critically evaluate the flow behavior of the CuZn39Pb2 continuous casting bar. The microstructure suggested that the processing map based on the Murty instability criterion was suitable for optimizing the process parameters of the CuZn39Pb2. The relationships between the characteristics of processing maps and the deformation mechanisms under different strains were analyzed on the basis of Murty instability criterion. Considering the theoretical analysis results and energy consumption economy, 690 °C ≤ T ≤ 720 °C with 1 s-1 ≤ έ ≤ 3 s-1 are the best process parameters for CuZn39Pb2 forging.

Determination of Thermo-Physical and Physical Properties of Complex Alloyed Brass

At present time complex alloyed brasses are widely used for manufacturing of parts worked in fray conditions. The mechanical and service properties of this alloys are provided by presence of different structural constituents in the structure of alloys. The wear resistance is a basic property of complex alloyed brasses. The information on actual problems in the industrial production of cast bars, semi-finished products and [ pfrts]-непонятно] of complex alloyed brasses is presented in the article. In accordance with the increasing requirements of consumers to reliability and service life of parts the complex alloyed brass Cu62Zn31.6Mn3Al2Si0.8Ni0.4Cr0.2 was proposed as a material for production of parts. The development of technology of melting and semi-continuous casting of complex alloyed brass is an important problem. Moreover, for estimation of thermal contition of ingot and simulation of the process of solidification of the ingot, it is necessary to know thermal physic and physical characteristics of an alloy. Therefore, the research on determination of heat conductivity, heat capacity and density of complex alloyed brass, depending on temperature, was carried out. The obtained experimental data can be used to thermos-technical calculation of thermal contition of ingot and simulation of the process of solidification of ingot during semi-continuous casting for the purpose of determination of technological parameters of casting.

Advancement of Plasma Cold-Hearth Melting for Production of Gamma Titanium Aluminide Alloys within Arconic

Utilization of gamma titanium aluminide alloys in aerospace and automotive/industrial applications has placed significant demand on melting sources for products to be used in cast, wrought, and direct-machining applications. There is also an increased demand for input stock used in gas atomization of powders. Current technologies used in ingot manufacturing include plasma arc melting, vacuum arc melting, and induction skull melting + centrifugal casting. Subsequent processing may include forging, re-melting + casting, or machining directly into components. Over the past six years, Arconic Engineered Structures has developed a robust melting method using plasma cold-hearth melting technology, including the design and implementation of a new 3-torch system to produce Ti-48-2-2 cast bars. General discussions concerning plasma cold-hearth melting, manufacturing challenges, and metallurgical attributes associated with cast Ti-48-2-2 bars will be reviewed. Emphasis will be on understanding the impact of hot isostatic pressing on internal voids, residual stress cracking and resulting mechanical properties.

Structure and properties of magnesium chip blanks

This article describes the practical application of hot extrusion for compaction of magnesium shavings in semi-finished products and the study of the influence of process parameters on the mechanical properties of the obtained MA5 (AZ80) magnesium alloy bars. Production of bars was carried out at different heating temperatures and plastic deformation degree to find technology provide the best combination of tensile and compressive properties. The resulting bars are somewhat higher in strength characteristics than the strength of deformed cast bars made from MA5 alloy, however, they are significantly lower in ductility.