The spray-formed deposit with hot gas atomization (gas temperature about 300 °C) shows lower deposit surface temperature and smaller grain size in comparison to the deposit produced under cold (PDF) High yield spray forming of small diameter tubes If the effect of increasing the atomization gas pressure is not sufficient, the melt flow is a key parameter reported earlier by Meyer et. al. [Mey12]. The reduction of the melt flow compared to conventional processes is a key parameter of the proposed process to make the spray forming of small diameter tubes possible at high yields.
It has not been proven if the effect of surface temperature on porosity is transferable to other deposit geometries or other materials. In the past it has been shown that the preheating of the substrate reduces porosity in vicinity of the substrate during spray forming of steel tubes [Wah1993, Aif2003]. AMT Advanced Materials Technology GmbH - Melt-SpinningThe melt-spinning process is characterized by a thin stream of a molten metal that will become in contact with a water cooled copper wheel. This process causes APPLICATIONS OF ATOMIZATION AND SPRAY as-sprayed steel can be attributed to the nature of rapid solidification of spray forming processing. As shown in Figure 1, the austenite grain size of the steel processed by spray forming is apparently reduced, resulting in the increased grain boundary area, and it means that the sites for the nucleation of ferrite and pearlite are increased,
The rapid solidification inherent during spray forming process prevented segregation and formation of irregular carbides,and enhanced he hot-working ability. Excellent microstructure and toughness were obtained by the decomposition and breakup of the carbides during hot working and annealing process. Microstructural Evolution in Spray Forming SpringerLinkJul 23, 2017 · Abstract. Spray forming is a casting process in which the molten metal is directly converted to a solid bulk with unique characteristics. When processed under optimum conditions, spray formed materials typically present microstructures composed of refined polygonal (non-dendritic) grains, uniformly distributed with low levels of micro- and macro-segregation. Microstructure characteristics of spray-formed high speed The microstructural evolution of spray-formed high speed steel during hot deformation was investigated as well as the effects of spray forming parameters on the porosity formation. Four distinct zones are identified in the as-deposited material, and interstitial porosity is present in the bottom and peripheral zones, while gas-related porosity is mainly found in the central zone.
II of this article, the effects of atomization gas chemistry and alloy compositions are addressed. II. FORMULATION A. Porosity Model As briey described previously, three major mechanisms of porosity formation during spray forming have been pro-posed, that is, gas porosity, interstitial porosity, and solid-ication shrinkage. Simulation of jet-flow solid fraction during spray forming May 28, 2017 · A numerical model was developed to simulate the jet-flow solid fraction of W18Cr4V high-speed steel during spray forming. The whole model comprises two submodels:one is an individual droplet model, which describes the motion and thermal behaviors of individual droplets on the basis of Newtons laws of motion and the convection heat transfer mechanism; the other is a droplet Volker UHLENWINKEL Head of Spray forming and Hot gas atomization in spray forming has been used for the first time to improve the quality of spray-formed tubular deposits. This technique reduces gas consumption and produces smaller droplets
In the spray forming process, the atomizing quality is not very good under the low pressure. This article attempts to improve the quality of atomization through heating the gas.