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.

Microstructural Characterization of Spray Formed Ni-Al-Cr-C Alloys

Abstract: In this study three Ni-Al-Cr-C nickel based casting alloys with 0.5, 1.0 and 1.5wt% carbon content were processed by spray forming aiming to investigate the potential of achieving substantial microstructure refinement by the high cooling rate involved in this process. Some attempts were done in order to evaluate the wear resistance of these alloys by means of pin-on-disk tests. Two values for the gas to the metal flow rate ratio, GMR, were used ( 0.12 and 0.23) and nitrogen was used as the atomization gas. The overspray powders and the deposit were characterized by using optical and scanning electron microscopy. The high cooling rate resulted in a strong microstructural refinement, with carbides of about two order of magnitude smaller than those obtained in the conventionally cast materials, dispersed in a predominantly gamma-prime matrix. Higher GMR led to a more refined microstructure due to higher cooling rate imposed to the atomized droplets. The micro structure observed in the deposit could be correlated with that observed in the overspray powders, indicating transformations during deposition process. The atomized alloys having higher carbon content (1.5%) and consequently higher volumetric fractions of carbides, presented better wear resistance. Their results are similar or slightly better than those obtained for a conventionally cast high chromium white cast iron.

The investigation and evaluation of the spray-formed states of tool steels to make a catalogue of materials properties available

Abstract: Spray forming is a new production route for high-alloyed steels. The product quality competes against the industrial established - here called conventional - production routes, i.e. ingot casting, continuous casting and powder metallurgy (hot isostatic pressing of gas atomised powder). At the step from RD just by moving the growing deposit relatively to the spray cone of gas atomised droplets in a sophisticated way. The solidification can take place within a thin partially liquid surface layer which solidifies incrementally making crystallisation and high temperature diffusion only effective over short distances. Grain growth and macrosegregation do not occur and impurities are small and evenly distributed. Until now for high-alloyed steels such property enhancement can be only obtained by powder metallurgy. The selection of steel qualities within this project has focused onto commonly used steels on the one hand to compare the qualities obtained by conventional production routes. On the other hand, the capability of the spray forming technique to produce steel grades, which show usually high degree of difficulty in conventional casting, requiring high knowledge and experience of the producer, should be examined. Therefore the selection first nominates the cold work tool steel AISI D2 (EN X153CrMoV12), being both available as ingot cast and powder metallurgical quality. Furthermore this alloy is one of the most commonly used alloyed cold work tool steels and has been used earlier for spray forming experiments. As a second alloy for comparison the high-speed steel M2 (EN HS6-5-2C) has been selected, showing higher complexity of the alloy composition. The hot work tool steel AISI H13 (EN X55CrMoV5-1) is used to consider a steel grade with lower content of alloying elements and lower carbon contents as the ledeburitic steels. This steel is very sensitive to microsegregation of elements affecting the hardening conditions (especially the Mo and V). The fourth steel (SAE51446 (EN X10CrAlSi25)) has lowest carbon content but a very high amount of alloying elements. Aluminium as an important alloying element in this alloy is more sensitive to the nitrogen gas, which is implemented in the spray forming process, than any other element within the alloys being considered. To complete existing modeling of the spray forming process, high temperature properties of the alloys are made available by experience of the industrial partners. For each alloy the process parameters are selected separately. In this way constant quality is ensured with respect to a reliable statistical approach. Following this attempt spray forming process batches are documented in detail and evaluated with respect to the later obtained results. A spray forming facility at the University of Bremen with a capacity of 150 kg liquid steel is used for the production of the spray formed material. Billets of about 200 mm diameter and a length of 450 mm have been produced obtaining weights up to 115 kg. Process variations

Production of high strength Al-Zn-Mg-Cu alloys by spray forming process

Abstract: High strength Al Zn Mg Cu alloys were produced by spray forming process, and compacted by hot extrusion. The results show that the as deposited billets have fine grained microstructure and low porosity. After heat treatment, mechanical properties increase greatly: tensile strength up to 754 MPa, yield strength up to 722 MPa, fracture elongation up to 8%, and elastic modulus up to 72 GPa, respectively. [

Effect of heat treatment on the microstructure and mechanical properties of spray-formed 7055 aluminium alloy

Abstract: 7055 Al alloys samples were prepared by spray forming and hot-extrusion followed by two different aging treatment procedures. Their different distributions of GP zones, and nanoscale precipitates η...