Laser and Hybrid Laser-Arc Welding

Laser and hybrid laser-arc welding are used at present in modern industry, having many advantages over traditional welding technology. Sectors such as the automotive industry, shipbuilding, aviation and space industry, chemical machinery, defense industry, and so on cannot be imagined without these technologies. Possibility of dramatic increase of weld joint properties, robustness, and high level of process automation makes the technology of laser and hybrid material processing a prospective part of the industry. At the same time, physical complexity of these processes, their cross-science nature, and necessity in high-level skilled stuff require many efforts for wide and successful industrial implementation. Present manuscript, devoted to discussion of physical peculiarity of laser and hybrid laser-arc welding of metals, approaches to physical-based design of technological equipment, as well as examples of industrial applications of laser and hybrid welding concerning the possibility to control welded metal structure and properties, is one of the steps on this way

Influence of the Gap Width on the Geometry of the Welded Joint in Hybrid Laser-Arc Welding

The aim of this research was the experimental investigation of the influence of the gap width and speed of the welding wire on the changes of the geometry in the welded joint in the hybrid laser-arc welding of shipbuilding steel RS E36. The research was divided into three parts. First, in order to understand the influence of the gap width on the welded joint geometry, experimental research was done using continuous wave fiber laser IPG YLS-15000 with arc rectifier VDU-1500DC. The second part involved study of the geometry of the welded joint and hardness test results. Three macrosections from each welded joint were obtained. Influence of the gap width and welding wire speed on the welded joint geometry was researched in the three lines: in the right side of the plates, middle welded joint and in the root welded joint

Hybrid welding of dissimilar metals

© Published under licence by IOP Publishing Ltd.The article addresses issues laser - plasma welding (LPW) dissimilar metals and the results of metallographic studies of the microstructure of welds ferrite - 40 steel and molybdenum - steel 40. Increasing potential opportunities the high-energy processing is carried out by integration the laser radiation (LR) and plasma, which allows you to create the desired spatial distribution of the energy flow for technological processes (TP) of laser-plasma heat treatment (LPT) of metals. The distribution of the thermal field is determined by the density distribution of energy flow LR and plasma exposure time, and the thermal characteristics of the treated metal. The most interesting is the treatment of details with ring flow of plasma and LR axial impact

Триботехнические характеристики композиционных покрытий на никелевой основе, полученных гибридными технологиями

As an object of this study, the coatings were used, which are composed of self-fluxing nickel-based alloys or compositions containing them, formed in a hybrid technological process with two main stages: spraying by the plasma method and subsequent remelting – by the gas-flame method or laser heating. An experimental measurement of their resistance to abrasive wear under conditions of boundary friction with the introduction of lubricants has been carried out for the coatings obtained in this process. At the same time, the influence of the coating composition and the remelting method on the wear value measured by the artificial base method has been investigated. To evaluate the dynamics of structure formation in the surface layer subjected to mechanical loads during the friction, X-ray diffraction analysis, metallographic method, and scanning electron microscopy in the electron diffraction mode have been used. After the laser remelting stage, it is possible to obtain coatings with wear resistance that is twice or more superior to the level for sprayed coatings of the same composition processed by the gas flame method. Wear of the coating surface has been found to occur through the mechanism of fatigue failure of the least hard component of the coating, i. e., the nickel-containing intermetallic phase, with the formation of an island-type film of hard crystallites of the carbide-boron phase weakly bound to the coating base, which ultimately leads to cracking of particles of this phase and their crumbling from the surface. The durability of layers obtained after the laser remelting stage can be increased, according to experimental data, by reducing the grain size of the phases in the coating and its texturing, as well as increasing the concentration of alloying elements in the composition of the metal-containing binder phase of the coating. The use of alloying additives leads to an additional increase in wear resistance by 2–4 times. This is due, depending on the type of additives, with an increase in the amount of the hardening phase while maintaining the plasticity of the matrix (coatings with chromium carbide additives), the degree of alloying of the nickel matrix (by the tungsten carbide and boron carbide additives), as well as the presence of a finely dispersed carbide-boride component, which reduces the processes of deformation and scratching.Как объект изучения использованы покрытия, состоящие из самофлюсующихся сплавов на основе никеля или содержащие их композиции, сформированные в гибридном технологическом процессе с двумя основными стадиями: напылением плазменным методом и последующим оплавлением – газопламенным методом или за счет лазерного нагрева. Для полученных в данном процессе покрытий проведено экспериментальное определение их стойкости к абразивному износу в условиях граничного трения с вводом смазок. При этом изучено влияние состава покрытия и способа оплавления на величину износа, измеренного методом искусственных баз. Для оценочного определения динамики структурообразования в поверхностном слое, подвергнутом механическим нагрузкам при трении, использованы рентгенофазовый анализ, металлографический метод, а также сканирующая электронная микроскопия в режиме электронной дифракции (электронографии). После стадии лазерного оплавления удается получить покрытия со стойкостью к износу, двукратно и более превосходящей уровень для напыленных покрытий того же состава, обработанных газопламенным методом. Износ поверхности покрытия, как было установлено, происходит по механизму усталостного разрушения наименее твердого компонента покрытия, т. е. никельсодержащей интерметаллидной фазы, с образованием островковой пленки из слабосвязанных с основой твердых кристаллитов карбидно-боридной фазы, что приводит в итоге к растрескиванию частиц этой фазы и осыпанию их с поверхности. Стойкость слоев, полученных после стадии лазерного оплавления, может быть повышена, по экспериментальным данным, путем уменьшения размеров зерна фаз в покрытии и его текстурирования, а также повышения концентрации легирующих элементов в составе металлсодержащей связующей фазы покрытия. Введение легирующих добавок приводит к дополнительному увеличению износостойкости в 2–4 раза. Это связано, в зависимости от типа добавок, с увеличением количества упрочняющей фазы при сохранении пластичности матрицы (покрытия с добавками карбида хрома), степенью легирования никелевой матрицы (добавки карбида вольфрама и карбида бора), а также наличием мелкодисперсного карбидно-боридного компонента, что уменьшает процессы деформирования и царапания

Hybrid welding of dissimilar metals

© Published under licence by IOP Publishing Ltd.The article addresses issues laser - plasma welding (LPW) dissimilar metals and the results of metallographic studies of the microstructure of welds ferrite - 40 steel and molybdenum - steel 40. Increasing potential opportunities the high-energy processing is carried out by integration the laser radiation (LR) and plasma, which allows you to create the desired spatial distribution of the energy flow for technological processes (TP) of laser-plasma heat treatment (LPT) of metals. The distribution of the thermal field is determined by the density distribution of energy flow LR and plasma exposure time, and the thermal characteristics of the treated metal. The most interesting is the treatment of details with ring flow of plasma and LR axial impact

Hybrid welding of dissimilar metals

© Published under licence by IOP Publishing Ltd.The article addresses issues laser - plasma welding (LPW) dissimilar metals and the results of metallographic studies of the microstructure of welds ferrite - 40 steel and molybdenum - steel 40. Increasing potential opportunities the high-energy processing is carried out by integration the laser radiation (LR) and plasma, which allows you to create the desired spatial distribution of the energy flow for technological processes (TP) of laser-plasma heat treatment (LPT) of metals. The distribution of the thermal field is determined by the density distribution of energy flow LR and plasma exposure time, and the thermal characteristics of the treated metal. The most interesting is the treatment of details with ring flow of plasma and LR axial impact