In Additive Manufacturing field, the current researches of data processing mainly focus on a slicing process of large STL files or complicated CAD models. To improve the efficiency and reduce the slicing time, a parallel algorithm has great advantages. However, traditional algorithms can’t make full use of multi-core CPU hardware resources. In the paper, a fast parallel algorithm is presented to speed up data processing. A pipeline mode is adopted to design the parallel algorithm. And the complexity of the pipeline algorithm is analyzed theoretically. To evaluate the performance of the new algorithm, effects of threads number and layers number are investigated by a serial of experiments. The experimental results show that the threads number and layers number are two remarkable factors to the speedup ratio. The tendency of speedup versus threads number reveals a positive relationship which greatly agrees with the Amdahl’s law, and the tendency of speedup versus layers number also keeps a positive relationship agreeing with Gustafson’s law. The new algorithm uses topological information to compute contours with a parallel method of speedup. Another parallel algorithm based on data parallel is used in experiments to show that pipeline parallel mode is more efficient. A case study at last shows a suspending performance of the new parallel algorithm. Compared with the serial slicing algorithm, the new pipeline parallel algorithm can make full use of the multi-core CPU hardware, accelerate the slicing process, and compared with the data parallel slicing algorithm, the new slicing algorithm in this paper adopts a pipeline parallel model, and a much higher speedup ratio and efficiency is achieved.

•Samples built by various scanning parameters can be classified into three types.•The scanning frequency has a significant impact on the material deposition.•α′-martensite within the top region provides an evidence of phase transformation.Electron Beam Selective Melting (EBSM) is an additive manufacturing technique that directly fabricates three dimensional parts in a layerwise fashion by using an electron beam to scan and melt the metal powder. In this study, the scanning parameters including beam current, scanning velocity and scanning line length were varied in a wide range of 2–18 mA, 250–2000 mm/s and 2–50 mm, respectively. The built samples of Ti-6Al-4V were characterized regarding the upper surface appearance, macro and microstructures and composition change. It was found that the built samples can be classified into three types: (I) porous surface with internal cavities; (II) dense and flat surface with pores at edge; and (III) significantly wavy surface. An increase in beam current, a decrease in scanning velocity or a decrease in the scanning line length, led to an evolution from type I to type II and finally to type III. The effects of beam current and scanning velocity can be evaluated by a combined parameter: energy density. The scanning frequency also has a significant impact on the extent of heat concentration, and thus affects the material deposition. In the samples of type II and III, the α′-martensite within the top region proves that the primary β phase firstly transforms into α′-martensite and then decomposes into α/β phase in continued building cycle. The causes of defects during the EBSM were also discussed.

Laser micro cladding deposition manufacturing (LμCDM) is a newly developed rapid manufacturing method for metals. The LμCDM technology adopts a novel powder feeding method based on alternating friction and inertia force, and this powder feeding method can effectively improve the accuracy and orientation of the powder injection, resulting in a smaller molten pool size and a higher cooling rate of liquid metal. Therefore, the components fabricated by LμCDM could obtain the finer microstructures and the improved mechanical properties. It is found that the components fabricated by LμCDM are fully dense free of cracks or pores and exhibit columnar prior β grains with a finer acicular α′ phase microstructure. The microhardness (HV0.2) of the thin-wall component is HV 400–HV 500 in the majority part of the cross section and can reach about HV 850 in the top region. The ultimate tensile strength (UTS) and elongation show insignificant dependence on the testing directions of the tensile specimens. The UTS is between 1,002 and 1,100 MPa, and the elongation is between 10.0 % and 14.7 %.

Electron beam selective melting (EBSM) is an additive manufacturing technique that directly fabricates three-dimensional parts in a layerwise fashion by using an electron beam to scan and melt metal powder. In recent years, EBSM has been successfully used in the additive manufacturing of a variety of materials. Previous research focused on the EBSM process of a single material. In this study, a novel EBSM process capable of building a gradient structure with dual metal materials was developed, and a powder-supplying method based on vibration was put forward. Two different powders can be supplied individually and then mixed. Two materials were used in this study: Ti6Al4V powder and Ti47Al2Cr2Nb powder. Ti6Al4V has excellent strength and plasticity at room temperature, while Ti47Al2Cr2Nb has excellent performance at high temperature, but is very brittle. A Ti6Al4V/Ti47Al2Cr2Nb gradient material was successfully fabricated by the developed system. The microstructures and chemical compositions were characterized by optical microscopy, scanning microscopy, and electron microprobe analysis. Results showed that the interface thickness was about 300 μm. The interface was free of cracks, and the chemical compositions exhibited a staircase-like change within the interface.

In electron beam selective melting process, powder pushed-away phenomena and uneven temperature field are two main obstacles, which are greatly associated with the electron beam scan mode. In this paper, various scan strategies, including iterative scan mode, reverse scan mode, interlaced reverse scan mode, randomized block scan mode, and constant length scan mode, are investigated. The analyses for each scan strategy are presented based on the influence to the temperature field over the formation zone and the powder pushed-away phenomena. The most promising strategy, interlaced reverse scan mode, is approved by the ANSYS simulation and a two-dimensional scan experiment. The result shows interlaced reverse scan mode can improve the uniformity of the temperature field and reduce the powder pushed-away phenomena.