Spray forming

About: Spray forming is a research topic. Over the lifetime, 1153 publications have been published within this topic receiving 12869 citations. The topic is also known as: spray casting & spray deposition.

Investigation on the microstructure and mechanical properties of the spray-formed Cu-Cr alloys

Abstract: Cu–1.2 wt.%Cr and Cu–3.2 wt.%Cr alloys were prepared by spray forming. The as-deposited alloys were subsequently warm rolled at 300 °C with a 40% reduction and then two types of thermo-mechanical treatments were adopted to enhance the mechanical properties of the Cu–Cr alloys. The microstructural features of the Cu–Cr alloys in different thermo-mechanical processing conditions were characterized using optical, scanning electron and transmission electron microscopy techniques. The results show that the spray-formed Cu–Cr alloys exhibit a better response to heat treatment compared to the conventional casting alloys. The chromium content has a great effect on the aging behaviors of the Cu–Cr alloys. Although a higher chromium content leads to a larger volume fraction of chromium precipitates generated during the solidification, it does not cause an increase in the mechanical properties. The chromium content should be lower than 1.2 wt.%.

Effect of heat treatment on microstructure and residual stress of wire arc sprayed high carbon steel coating

Abstract: The 0·8% carbon steel wire was used to deposit coating, and the coated samples were annealed at 550, 650 and 800°C respectively, which were then quenched in water. The microstructure, phase composition and residual stress of the heat treated coatings were studied and compared with that of the coating without any post-treatment. Results show that the heat treatment processes have significant influences on coating oxide, steel alloy grains and residual stresses. The high carbon steel coating expressed tensile stress after spraying, but when the special quenching process was applied, martensite and bainite were formed in the coating, resulting in expansion of material volume, which made the residual stress of the coating change from tension to compression. The correlation between the microstructure and residual stress strongly informed that phase transformation in the coating should be carefully controlled if spray forming thick coating is aimed.

Spray forming of Ti 48.9Al (at.%) and subsequent hot isostatic pressing and forging

Abstract: Binary Ti 48.9Al (at.%) has been processed via two different processing routes, both comprising the spray forming technology: (i) spray forming followed by hot isostatic pressing (HIP) and subsequent thermal treatments and (ii) spray forming and subsequent high temperature forging. After each process step, the material is characterized by porosity measurements, microstructural investigations and tensile tests. The as sprayed state is characterized by a porosity of 1.0%. Both, HIP and forging yield a further reduction in porosity to 0.06 and 0.04%, respectively. The as sprayed microstructure is of high homogeneity, which is maintained during all subsequent treatments. High strength (UTS=470 MPa) and a plastic elongation of 0.9% have been measured for the nearly lamellar as sprayed microstructure. The duplex microstructure, which has been established by a specific heat treatment subsequently to HIP provides the highest plastic elongation of 2.7%. The fine near gamma microstructure after forging shows at 2%-plastic elongation the highest strength (UTS=520 MPa) among the various microstructures.

Modeling and microstructure development in spray forming

Abstract: Models of the spray forming process from different groups show reasonable agreement with each other and with the real process. Use of these models has provided considerable insight into the several complex processes involved in spray forming; in addition, the models allow designed experiments to provide further insight into the process. In the work described it has been shown that the modeled fraction of liquid in the spray f j (s) appears to be an appropriate control parameter for spray forming. Sticking efficiency and porosity have been found to correlate well with f j(S) . The differences found in the optimum value of the fraction of liquid in the spray for billets (0.3) and tubes(0.5-0.6) indicate, however, that the actual control parameter may be the fraction liquid in the deposit, f j (d) on the surface under the spray. The need for improved modeling, particularly of the full thermal profiles in complex geometries such as spray deposited tubes, is discussed as is the value of improved process diagnostic tools for direct experimental measurement of such features as droplet sizes and velocities, and the deposit temperatures in actual spray forming processes.