Papers by Keyword: Cladding

Abstract: In the present study, a two-dimensional steady state laminar flow model was developed using fluent software in order to investigate the possibility of achieving Mg/Al cladding using a horizontal twin roll caster. The effects of parameters such as upper and lower inlets casting sequence, solidification length on the temperature field at the bond interface and outlet thickness direction were investigated. The feasibility of the model was verified by combining with experiments. The results show that the molten A5052 alloy with a high melting point is more suitable to be cast by the lower roll at the roll speed of 9 m/min and the roll gap of 5 mm. The temperature of the A5052 and AZ91 near the bond interface of the clad strip can be controlled by the solidification length. Numerical simulations can provide guidance for the optimal casting process parameters.

Abstract: The aim of the experimental work was to propose innovative procedures for the formation of renovation layers, to determine suitable material, modify the microgeometry and surface topography of new and renovated shaped parts of moulds for high-pressure casting of aluminium alloys. It has been designed and validated under laboratory and operational conditions a method of modifying the surface of the mould parts of moulds for casting aluminium alloys by forming stochastic texture by low energy laser in combination with duplex PVD coatings on the surfaces of mould parts in contact with the aluminium alloy melt. It has been verified the contact angle measurement methodology for determining the number of spurs by separation lubricant on the surface of the new or refurbished mould part before the first casting cycle. For the formation of the renovation layers, the additive materials were verified Dievar, Dratec, UTPA 702. A TruDisk 4002 solid-state disk laser with BEO D70 focusing optics was used for winding.

Abstract: In-situ evaluation of crack generation using acoustic emission (AE) technique as a non-destructive testing method was applied during laser cladding of WC-Co cemented carbide via a multi-beam laser metal deposition (LMD) system. Especially, this study aims to investigate relationships between the laser output and the number of cracks generated in beads of WC-12mass%Co cemented carbide cladded by the LMD system. The number of cracks was evaluated using an AE sensor attached to a substrate. The number of cracks was also evaluated from SEM images of beads. By comparing these results, problems in the both evaluation methods for crack generation in laser cladding were discussed.

Abstract: The current work investigates the impact of MOX fuel introduction on AP1000 neutronic characteristics. The MCNP code with new silicon carbide cladding and the AP1000 core with three 235U enrichment zones (2.35%, 3.40%, and 4.45%) were used to perform the neutronic computations. The outcomes demonstrated that the simulated model for the AP1000 core complies with the optimization requirements as a Westing-house reference. The results which included: effective multiplication factor, k_eff, and excess reactivity were calculated and compared with the available published results. The k_eff in the cold zero power was found to be AP1000 Zircaloy, SiC, FeCrAl, and SS-310 cladding are (1.20685+/-0.00028), (1.21170+/-0.00028), (1.14435+/-0.00027), and (1.12432+/-0.00028). The excess reactivity is 17.11%, 17.47% 12,61%, and 11.06% with the MOX fuels, respectively. These numbers line up with the k_eff value of 1.205 given in the AP1000 Design Control Document for the UO2 fuel core. However, the results are positive and support the AP1000 reactor core's design and efficient modeling as being safe operation.

Abstract: Aluminium alloy 2024 is widely used in the manufacturing of aircraft components such as skin panels for the wing. Generally, the aluminium alloy 2024 is delivered as cold work condition i.e., 2024 T3. However, the aluminium alloy 2024 T3 does not meet the standard for aircraft wing skin. Therefore, further treatments such as cladding and heat treatment are carried out to improve its quality. Cladding was introduced to the 2024 T3 alloy at 495 °C using commercial purity aluminium. Subsequently, T42 heat treatment was introduced to the 2024 T3 alloy at 500 °C for 40 minutes, then followed by quenching and natural aging for 96 hours, yielding 2024 T42 aluminium alloy with cladding (T42 Clad). 2024 T42 aluminium alloy without cladding (T42 Bare) was also obtained by T42 heat treatment of 2024 T3. The effect of cladding and natural aging on mechanical properties is investigated by tensile test and hardness test. Conductivity meter was used to determine the electrical conductivity. Intergranular corrosion test and stress corrosion crack test were performed to investigate the effect of cladding and natural aging on corrosion resistance. Results indicate that the solution treatment and natural aging improve corrosion resistance, mechanical properties, but reduce electrical conductivity values. Cladding gives higher electrical conductivity value and elongation. Both natural aging and cladding treatment provide appropriate aluminium alloy for aircraft wing skins.

Abstract: The influence of mechanoactivated reagents cladding on the structural-phase state of the SHS-products was investigated. Titanium and aluminum powders were used as reagents. Mechanical activation was performed on the AGO-2 planetary ball mill. The coating on Ti+Al mechanocomposite was carried out using magnetron installation “VSE-PVD-Power”. At deposition time of 40 minutes, the reaction start temperature increases from 525 °C to 648 °C (compared to reagents without cladding). It can be assumed that an increase in the thickness of the deposited SiO₂ film serves as a barrier to the reaction start, thereby increasing ignition temperature. Apart from pretreatment, the phase composition of the final product contains intermetallic compounds TiAl, TiAl₃, Ti₃Al₅, as well as the small amount of residual Ti. The main phase is TiAl.

Abstract: During cladding an austenitic layer on low-carbon and medium-alloyed steels, the properties of the heat-affected zone, along with the resistance of the surface layer to resist corrosion, largely determine the performance and durability of the surfaced product. The work is devoted to the study of the dependence of the properties of the heat-affected zone during cladding of power equipment with austenitic materials on the parameters of the control mechanical impacts on the strip electrode and determination of their optimal range, which ensures high values of the mechanical properties of the deposited layer.

Abstract: This study aimed to compare the X3CrNiMo17-13-3 stainless steel based plasma transferred arc (PTA) cladded hardfacings, reinforced with the in-situ synthesized Cr and Ti carbides. Carbon black and either pure Cr, pure Ti, or TiO₂ were utilized as reinforcement precursors (the respective hardfacings are further referred to as Cr+C, Ti+C and TiO₂+C). The pre-placed mixtures of matrix and reinforcement precursor powders were remelted by the plasma transferred arc, applying the preliminarily optimized process parameters (95 A, 22 – 24 V, 0.2 mm/s). As a reference, the unreinforced stainless steel hardfacing was used. The carbide reinforcement was successfully in-situ synthesized in all the hardfacings. The Cr + C hardfacing exhibited the largest average hardness (556 ± 29 HV1), while the TiO₂ + C hardfacing had the largest average Young’s modulus (156.3 ± 19.7 GPa). The Cr + C and Ti + C hardfacings demonstrated the 2.3 and 2.1 times higher resistance to abrasive wear than the reference hardfacing. The TiO₂ + C hardfacing showed 1.5 times lower wear resistance than the reference hardfacing presumably due to a lack of the reinforcement and a lower strain hardening ability.

Abstract: The paper presents the manufacturing process of two classes of material that feature intelligent precursors, used for welding/cladding, and deposit layers with viable physical proprieties, that can be predetermined by a precise and well-balanced programming of the process parameters. The fields of use for these materials are those of manufacturing welded structures that have equal resistant joints, made from stainless steel with austenitic-ferrite-martensitic structure or mixes of the above mentioned structures, with the possibility of machining, in welded state, namely with self-hardening proprieties during exploitation. The methods of securing the above mentioned materials is programming, according to exploitation requirements, of the preheating and in between rows temperature, as well as the dilution degree of the filler into the base material. Results obtained by structural or morphological changes of the crystalline grains are determined by perturbing the equilibrium state and/or precipitation of secondary phases. The field of use of the methods above mentioned are valid in the interval: 30-55 HRC, namely 500-1200 N/mm².

Abstract: This study introduces the direct cladding of magnesium and aluminum alloys using a horizontal twin roll caster in one step. A horizontal twin roll caster can cast a Mg/Al clad strip with thickness exceeding 5mm at a roll speed of 8m/min in one step, which is difficult for a vertical twin roll caster. Therefore, it is possible to cast a thick clad strip with different melting point alloys using a horizontal twin roll caster at low speed. It is also possible to cast clad strips using as the overlay an alloy that has a higher melting point than that of the base strips. The thickness of the Mg/Al clad strip is 6.5mm, and the ratio of the Mg layer to the Al layer is 3:2. The surface of the clad strip is good, and there is no void between bonding interfaces. The mixing layer of the bonding interface is deeply related to the reduction rate. As the reduction rate increases, the mixing layer becomes more balanced and the thickness of the mixed layer decreases to 68μm. By observation of the interface of the cladded material, the mixed layer of the bonding interface is divided into two layers. It has been found the mixed layer near the Al layer has the highest hardness (up to 228HV), and the tensile shearing strength of the manufactured Mg/Al clad strip was 44MPa.