Microstructure and Mechanical Properties of Narrow Gap Laser-Arc Hybrid Welded 40 mm Thick Mild Steel
Both laser-arc hybrid welding and narrow gap welding have potential for the fabrication of thick sections, but their combination has been seldom studied. In this research, 40 mm thick mild steel was welded by narrow gap laser-arc hybrid welding. A weld with smooth layer transition, free of visible defects, was obtained by nine passes at a 6 mm width narrow gap. The lower part of the weld has the lowest mechanical properties because of the lowest amount of acicular ferrite, but its ultimate tensile strength and impact absorbing energy is still 49% and 60% higher than those of base metal, respectively. The microhardness deviation of all filler layers along weld thickness direction is no more than 15 HV0.2, indicating that no temper softening appeared during multiple heat cycles. The results provide an alternative technique for improving the efficiency and quality of welding thick sections.
Defects and process tolerances in welding of thick plates
Laser welding and laser-GMA-hybrid welding using 8 kW, 20 kW and 30 kW fiber lasers was investigated. Steel plates from low alloyed steel (e.g. pipeline steel X65) having a thickness of 16 mm up to 28 mm were joined under various conditions. Single layer laser-GMA-hybrid welding as well as multi layer hybrid welding were investigated for different seam preparation types. Butt welds and different types of Y-welds have been tested. The air gap and the edge misalignment have been varied intentionally to investigate the process window as it is also intended to use the process in rough environment. Different types of phenomena which reduced the efficiency of the process (measured by the welding depth) were detected. In laser welding a significant influence of the focal length was seen, in which a short focal length reduced the penetration depth strongly. Multi layer hybrid welding resulted in pore formation while single layer hybrid welding showed reasonable good results.Laser welding and laser-GMA-hybrid welding using 8 kW, 20 kW and 30 kW fiber lasers was investigated. Steel plates from low alloyed steel (e.g. pipeline steel X65) having a thickness of 16 mm up to 28 mm were joined under various conditions. Single layer laser-GMA-hybrid welding as well as multi layer hybrid welding were investigated for different seam preparation types. Butt welds and different types of Y-welds have been tested. The air gap and the edge misalignment have been varied intentionally to investigate the process window as it is also intended to use the process in rough environment. Different types of phenomena which reduced the efficiency of the process (measured by the welding depth) were detected. In laser welding a significant influence of the focal length was seen, in which a short focal length reduced the penetration depth strongly. Multi layer hybrid welding resulted in pore formation while single layer hybrid welding showed reasonable good results.
CNC Desktop Vertical Machining Bench Design and Cooling Fluid Application
Today's manufacturing technologies, the human work force is used and at least a minimum level of margin of error is used in CNC machines. Desktop CNC machine tools and CNC machine tools are developed in parallel with the development of personal computers. This study provides CNC training institutions for education, small and medium-sized enterprises for commercial purposes use the low-cost desktop machine has been designing and manufacturing of CNC vertical machining was carried out. Desktop CNC machine tools and production capacity to handle the kind of material was applied to increase the cooling fluid. Through A199 and Fe37 the cooling fluid application desktop CNC machine tools, such as processing of materials that are difficult to successfully processed. Keywords—CNC, Desktop CNC Machine, CNC Design