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Influence of Post-Weld Processing Techniques on Laser Beam-Welded Ala??3Mga??0.25Sc Alloy Sheets
摘要： Fusion welding in aluminium alloys had always remained an issue for aero- and auto industries. An Al–3Mg–0.25Sc alloy is classi?ed as weldable aluminium alloys. In this study, two welding techniques, keyhole and conduction welding, have been used for joining Al–3Mg–0.25Sc sheets of thickness 1.6 mm. Experiments were carried out using different beam diameter (0.16–2 mm dia), beam power (2–4.5 kW) and laser head speed (ranging from 0.5 to 6 m/min). The results for all autogenous keyhole welding clearly demonstrated a drop in ductility (\ 0.8%) compared to base metal for all beam power and welding speed combinations although the yield strength was reasonably good (175–180 MPa, i.e. [ 50% of base metal). Residual stress-induced distortions affected the ?nal shape of the product, and for that, a suitable stress relief annealing was also required. Hereby, we chose two heat treatment schedules: (1) solution treatment and annealing and (2) retrogression and re-ageing. Retrogression and re-ageing is a precipitation-controlled phenomenon and comprises of an intermediate annealing step between tempering and solutionizing temperature to dissolve the nano-clusters present in the matrix (retrogression) and re-precipitating and growing them by ageing (re-ageing). These two steps were repeated cyclically, and as a result, the strength (190 MPa) and ductility (* 9%) of the material were improved substantially. The improvement of ductility and strength was explained in detail in the light of microstructural studies.
关键词： Strength,Post weld treatment,Weldment,Al-3Mg-0.25Sc alloy,Ductility,Laser welding
更新于2025-09-19 17:13:59
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Eliminating continuous grain boundary α phase in laser melting deposited near β titanium alloys by heat treatment
摘要： Continuous grain boundary α phase (αGB) is widely present in laser melting deposited near β and β titanium alloys, and it can lead to intergranular fracture and low ductility. Because of the preferential nucleation and growth of α phase at β grain boundaries, the continuous αGB cannot be effectively eliminated by traditional heat treatment. Thus, in this study, we develop a new heat treatment including beta solution + ultra-slow furnace heating up + traditional heat treatment, to eliminate continuous αGB in laser melting deposited Ti-5Al-5Mo-5V-1Cr-1Fe near β titanium alloy, and the microstructures and tensile properties are investigated. The results indicated that, after beta solution + normal heating up + traditional heat treatment, the continuous αGB still exists, and the elongation is still low about 7.5%. However, after beta solution + ultra-slow heating up + traditional heat treatment, there are almost no continuous αGB, and the elongation increases to 15.2%. The mechanism about the αGB formation during ultra-slow heating up process is simply revealed. Furthermore, this new heat treatment is also suitable to eliminate continuous αGB for laser melting deposited Ti17 alloy.
关键词： ductility,continuous grain boundary α phase,laser melting deposition,heat treatment,near β titanium alloys
更新于2025-09-12 10:27:22
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Experimental Investigations on the Effects of Multicomponent Laser Boriding on steels
摘要： In this investigation, the effects of the multicomponent (Ni+Cr+B4C) laser boriding on the microstructure, microhardness, ductility and toughness of AISI 1020 steel are studied. Thick, hard, non-acicular and uniform boride layer are obtained as a result of laser boriding. The impact test results indicate that the laser borided specimens treated at higher energy densities of the laser beam have better ductility and toughness as compared with the specimens treated with lower energy densities of the laser beam as well as the continuous and the interrupted borided specimens.
关键词： Microstructure,Multicomponent boriding,Laser beam,Hardness gradient,Steel,Ductility and Toughness
更新于2025-09-12 10:27:22
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Computer aided design of the laser dieless drawing process of tubes from magnesium alloy with take into account ductility of the material
摘要： Paper is devoted to the laser dieless drawing of the tubes made of magnesium alloy ZEK100. Important limitation of this process is a low ductility of magnesium alloys. The purpose of this work was the development and implementation into the FEM code, the ductility model of ZEK100 magnesium alloy and experimental validation of proposed methodology of process design. Ductility and flow stress models were developed based on tension and compression tests in temperature interval 20-350 °C. As result of this work, the technological diagrams for determination of diameter of tube after laser dieless drawing process were obtained.
关键词： Ductility,Dieless drawing,Tube,Magnesium alloys
更新于2025-09-12 10:27:22
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Investigation of Improvement of Electronic Properties and Ductility of RuAl2 Semiconducting Material by Boron Doping Using First-Principles Calculations
摘要： The occupation mechanism and influence of B doping on the electronic and mechanical properties of RuAl2 semiconducting compound have been investigated using first-principles calculations. Four possible B doping sites are considered. The results show that B-doped RuAl2 is thermodynamically stable. In particular, B element prefers to occupy B(4) site in comparison with other sites. Importantly, B doping improves the electronic properties of RuAl2 by shifting the Al 3p and Ru 4d states from the Fermi level (EF) to the valence band. Although B doping weakens the resistance to volume and shear deformation as well as the elastic stiffness of RuAl2, it improves the ductility due to the formation of Ru-B and Al-B bonds. Therefore, it can be concluded that B is a favorable doping element to improve the electronic properties and ductility of RuAl2 semiconducting compound.
关键词： Boron doping,RuAl2,First-principles calculations,Ductility,Electronic properties
更新于2025-09-04 15:30:14