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.

Effect of reactive elements on porosity in spray-formed copper-alloy Billets

Abstract: In spray-formed preforms, porosity is unavoidable. This is because the atomising gas becomes entrapped during the process. Normally, nitrogen is used for atomisation and therefore the voids are filled with this gas, which is not soluble in copper. To obtain a dense material after further forming processes such as extrusion, forging or drawing, porosity has to be limited to a specified level. There are means to influence porosity inside the spray-formed billet. To a certain extent, porosity can be influenced by process parameters. Reactive elements inside the alloy have an additional effect, that is reaction of elements such as Zr, Ti, Al with the entrapped nitrogen. Until now, a detailed explanation has not been given, however, a theory of hot porosity formation is presented in this paper. The calculated content of nitrogen and titanium-nitride is verified using analytical methods. The addition of titanium into the melt can reduce porosity by a factor of three.

Spray formed bearing steel insensitive to distortion

Abstract: To minimize the distortion of bearing steel components during manufacturing processes, 100Cr6 steel (SAE 52100) has been produced by spray forming as an alternative approach to conventional continuous casting process Material characteristics and distortion behaviour of the spray formed 100Cr6 steel were investigated in comparison with continuous cast material The investigation showed that the spray formed 100Cr6 steel exhibited lower distortion potential than the conventional material due to much better metallurgical homogeneity

Spray forming of the glass former Fe83Zr3.5Nb3.5B9Cu1 alloy

Abstract: The glass former Fe 83 Zr 3.5 Nb 3.5 B 9 Cu 1 (at.%) alloy was processed by spray forming. The aim was to investigate the possibility of forming novel microstructures using this process. The ratio between the gas mass flow rate and the metal mass flow rate used was 0.23, and nitrogen was used as atomization gas. The resulting deposit, weighting about 0.8 kg, as well as the overspray powder with a median particle diameter about 150 μm, were characterized by using X-ray diffratometry, differential scanning calorimetry and scanning electron microscopy with energy dispersive spectroscopy. Saturation induction ( B s ), maximum permeability ( μ max ) and coercive field ( H c ) were measured. The overspray powder showed a microstructure consisting of amorphous and α-Fe phases. The volume fraction of the amorphous phase decreased as the granulometric size range increased. The deposit presented fully crystalline structure with α-Fe, Fe 3 Nb, Fe 2 Zr and Fe 2 B phases. The formation of amorphous phase in the overspray and its absence in the deposit indicates that the deposit was formed by the impacting of a high volume fraction of fully liquid droplets, providing temperature and time enough for complete crystallization of the deposit.

Electrochemical Corrosion Behavior of Spray-Formed Boron-Modified Supermartensitic Stainless Steel

Abstract: Spray-formed boron-modified supermartensitic stainless steel (SMSS) grades are alloys developed to withstand severe wear conditions. The addition of boron to the conventional chemical composition of SMSS, combined with the solidification features promoted by the spray forming process, leads to a microstructure composed of low carbon martensitic matrix reinforced by an eutectic network of M2B-type borides, which considerably increases the wear resistance of the stainless steel. Although the presence of borides in the microstructure has a very beneficial effect on the wear properties of the alloy, their effect on the corrosion resistance of the stainless steel was not comprehensively evaluated. The present work presents a study of the effect of boron addition on the corrosion resistance of the spray-formed boron-modified SMSS grades by means of electrochemical techniques. The borides fraction seems to have some influence on the repassivation kinetics of the spray-formed boron-modified SMSS. It was shown that the Cr content of the martensitic matrix is the microstructural feature deciding the corrosion resistance of this sort of alloys. Therefore, if the Cr content in the alloy is increased to around 14 wt pct to compensate for the boron consumed by the borides formation, the corrosion resistance of the alloy is kept at the same level of the alloy without boron addition.

Spray forming and subsequent forging of γ-titanium aluminide alloys

Abstract: Spray forming experiments with a binary Ti–48.9Al (at.%) alloy and an advanced γ-TiAl alloy with the composition Ti–47Al–4(Nb, Mn, Cr, Si, B) (at.%), designated as γ-TAB, were carried out. Subsequently, the spray formed materials were forged. The sprayed and forged conditions were characterized in terms of microstructure, porosity, and impurity content. Tensile properties were evaluated at room and elevated temperatures. Upon forging the microstructures turned from nearly lamellar to near γ with a grain size of 4.9 μm (Ti–48.9Al) and from duplex to near γ with a grain size of 2.2 μm (γ-TAB) owing to dynamic recrystallization. The porosity of the spray formed materials almost vanished after forging. The room temperature (RT) tensile strength was improved due to the significant microstructural refinement. The sprayed and forged γ-TAB alloy sustains an elongation of 120% at 800 °C indicating the possibility of superplastic forming. The results are discussed in comparison with conventionally P/M-processed and hot isostatically pressed materials of the same composition.