Papers by Keyword: CMT

Abstract: Wire arc additive manufacturing (WAAM) according to ISO/ASTM 52900:2021 is a widely known additive manufacturing process to produce a new 3D part or repair a damaged metal part. Copper-based alloy, i.e., CuAl8, is widely used to repair marine structures and to make bearing overlays due to its excellent corrosion and wear resistance properties. This paper will give an insight into the multi-layer deposition of CuAl8 at different substrate orientations. Furthermore, multi-material deposition, i.e., CuAl8 and mild steel, is investigated, which can help industries to combine the features of both materials and lead to the development of functionally graded materials.

Abstract: This paper presents an investigation on the microstructure and mechanical property of Al-alloy parts made by using additive manufacturing based on CMT (Cold Metal Transfer) welding technology. With the same 3D model and process parameters, a set of hollow cylindrical parts with 100 layers were built up using 2319, 4043, 5356 aluminum welding wires, respectively. Then their microstructure, tensile strength, and microhardness were tested and analyzed comparatively. The layer bands characteristics were obviously observed in both 2319 and 4043 parts. In the interlayer region of the 2319 parts, the segregation of alloying elements on the grain boundaries and inside the grains were significantly more than that in the fusion line region. For the microstructure of 4043 parts, the dendrites grow upward from the bottom without interruption in the fusion line region, and the continuous growth structure was maintained. There is no obviously change on the microhardness from the bottom to the top because the organization is uniform and there is no significant difference in the grain size. The ultimate strength and elongation in the horizontal direction were higher than those in the longitudinal direction, and the 5356 parts had best mechanical properties among the three materials. Ultrasonic method was also used to measure the Young's modulus of the additive manufactured parts. The Young's modulus measuring results were accordant with the results obtained by the mechanical property testing, and the error was within 3%.

Abstract: For the examination of noxious emissions, cladding tests were performed according to EN ISO 6847. The filler materials were 1.2 mm diameter wire-electrodes, made of tin bronze, aluminium bronze, austenitic stainless steel, duplex stainless steel and nickel alloy.The low-energy metal transfer welding process, named CMT (cold metal transfer) was examined, on the welding source type Trans Puls Synergic 2700 CMT, of 270 A, produced by the company Fronius, Austria. For sampling welding smoke particles, an Apex type pump was used. For measuring the concentration of gases emitted by welding, a Triple Plus type multi-gas detector was applied.The particulate emission rate is 0.500 mg / m3 in the breathing zone, according to ISO 10882-1. For comparison, the measured emission rate is from 0.877 to 2.513 mg / m3 in the welding zone, according to ISO 15011-1. The concentration of the emitted gases is in the ranges: 0.14 to 0.16% CO2; 0.1-0.2 ppm NO2; 0-15 ppm H2; 0-5 ppm CO. These concentration levels are below the exposure limits (8 hours per day, five days a week): 5% CO2; 1.0 ppm NO2; 30 ppm CO. In conclusion, the emissions from the CMT welding process are without health risk for the welder.

Abstract: The article presents the course and the results of research on comparison of material and technological welding conditions of EN AW 6082 aluminium alloy using low energy (CMT) and pulsed current (MIG-Pulse) welding methods, as well as discusses the properties of welded joints and the application fields of modern low energy welding devices for joining thin aluminium sheets.

Abstract: The article presents the course and the results of research on welding conditions and tendency of hot cracking occurrence connected with MIG (CMT or Pulse) welding method choice. EN AW 6082 alloy is considered hard-to-weld by using conventional arc welding processes (MIG-Pulse) due to the heat sensitivity and the tendency to hot cracking in the thin walled joints (weld, HAZ). MIG low energy method (CMT) was developed inter alia to solve this problem.

Abstract: Earthquake prediction is one of the most difficult problems in modern natural science. Undoubtedly, various seismic parameters included in broadband radiated energy catalogue of NEIC is very important data source of investigate correlation between different earthquake within specific time space scope. In the paper, a fitting mode of seismic energy based on Support Vector Machine is established, using which we can fill the absent energy filed in the broadband radiated energy catalogue.

Abstract: The previous studies showed that the concurrent multi-path transmission (CMT) schemes can only play their advantage in the narrow-band networks (the most CMT experiments use 2M bandwidth). In this paper, the authors investigate the performance profits of CMT schemes with various network bandwidths. The simulation results show that the CMT schemes can work better in broad-band networks (e.g., over 20M bandwidth) than in narrow-band networks. This also implies that the CMT schemes have the potential to be applied in the field of multimedia transmission.

Abstract: The article presents the course and the results of research on material and technological welding conditions of 7xxx aluminium alloy using low energy welding method (CMT) as well as discusses the properties of welded joints and the application fields of modern low energy welding devices for joining thin aluminium sheets.

Abstract: Earthquake prediction is one of the most difficult problems in modern natural science. Undoubtedly, various seismic parameters included in broadband radiated energy catalogue of NEIC is very important data source of investigate correlation between differernt earthquake within specific time space scope and earthquake prediction. In the paper, we a linear fitting mode of seismic magnitude based on method of least squares and seismic energy is established, using which we can fill the absent energy filed in the broadband radiated energy catalogue.

Abstract: t is presented a method for determining the mechanical characteristics based on the vibration response of the CMT (Cold Metal Transfer) joints from thin sheets of stainless steel joined with CuSi3 filler wire. The experimental results obtained by vibration testing will be compared with the theoretical results, and with those obtained by classical methods from stress-strain diagram. Technical details are given also for obtaining these joints (parameters, equipment specifications) indicating also their applicability.