Melting and Casting of Titanium Alloys

2007 ◽  
Vol 539-543 ◽  
pp. 3601-3606 ◽  
Author(s):  
Si Young Sung ◽  
Young Jig Kim
Keyword(s):  
Titanium Alloys ◽  
Fatigue Property ◽  
Unique Property ◽  
Specific Yield ◽  
Forming Process ◽  
Good Corrosion Resistance ◽  
The Past ◽  
Alpha Case ◽  
Near Net Shape ◽  
Net Shape Forming

Over the past decades, a large number of researchers have been trying titanium alloys in an attempt to combine most of their advantages, such as high specific yield strength, good corrosion resistance, excellent fatigue property and biocompatibility by casting route. However, the wide use of titanium alloys casting has been limited, since it is considered as only a near net shape forming process in titanium alloys due to the catastrophic reactivity of molten states, the alpha-case formations and the casting defects. In order to maximize the unique property of titanium alloys casting which are comparable to wrought products and quite often superior, it is necessary to take a close examination of titanium alloys casting procedure. Therefore, the merits and demerits of various melting devices, pouring methods and mold materials will be addressed with regard to improving titanium alloys casting.

Numerical Simulation of the Auto Claw-Pole Thixoforming Process

2011 ◽  
Vol 66-68 ◽  
pp. 1605-1610
Author(s):  
Van Luu Dao ◽  
Sheng Dun Zhao ◽  
Wen Jie Lin
Keyword(s):  
Complex Geometry ◽  
Hot Forging ◽  
Strong Impact ◽  
Forming Process ◽  
Billet Temperature ◽  
Punch Speed ◽  
Initial Billet ◽  
Near Net Shape ◽  
Net Shape Forming ◽  
Die Temperature

Thixoforming is an effective near-net-shape forming process to produce components with complex geometry and in fewer forming steps. In this study, thixoforming was used to replace the conventional hot forging to form the auto claw-pole. The finite element code Forge2008Ó was used to simulate the auto claw-pole thixoforming process. The results show that initial billet temperature, punch speed, die temperature and friction have strong impact on the forming process. Finally, the reasonable process parameters for the auto claw-pole thixoforming were obtained: initial billet temperature 1430~1440°C, punch speed 100~200mm/s and die temperature 300~400°C.

Novel Direct Coagulation Casting of Alumina Suspensions Using Y3+-Ion Releasing Substances as Coagulant

2014 ◽  
Vol 602-603 ◽  
pp. 164-169
Author(s):  
Yue Dong ◽  
Xiao Dong Li ◽  
Shao Hong Liu ◽  
Ji Guang Li ◽  
Xu Dong Sun
Keyword(s):  
Complex Shape ◽  
High Density ◽  
Green Body ◽  
Alumina Ceramics ◽  
Forming Process ◽  
Coagulation Time ◽  
Near Net Shape ◽  
Net Shape Forming ◽  
Alumina Suspensions

Direct coagulation casting (DCC) is a relatively new ceramic near-net-shape forming process which can form homogeneous ceramic green body with complex shape and high density. Direct coagulation casting of aqueous alumina slurries by adding Y3+ions, which have been frequently used as additive for the sintering of alumina ceramics, were studied. Two different kinds of Y3+-ion releasing substances, Y2O3powder and Y(NO3)3, were used as coagulants and were introduced into stabilized alumina suspensions directly after dispersing. Compared with that of Y2O3powder, both the coagulation time and the added amount required for a reasonable shaping were significantly reduced for using Y(NO3)3as coagulant. The effects of the two coagulants on the properties of the consolidated green bodies and sintered ceramics were studied. The mechanisms of coagulation induced by the addition of Y3+-ions were discussed on the basis of interactions between Y3+ions and the added polyelectrolyte dispersant.

Near Net-Shape Forming of Thermal Barrier Coated Components for Gas Turbine Engine Applications

1998 ◽  
Author(s):  
G.E. Kim ◽  
P.G. Tsantrizos ◽  
S. Grenier ◽  
A. Cavasin ◽  
T. Brzezinski
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Gas Turbine ◽  
Bond Coat ◽  
Gas Turbine Engine ◽  
Thermal Barrier ◽  
Forming Process ◽  
Turbine Engine ◽  
Near Net Shape ◽  
Net Shape Forming

Abstract PyroGenesis Inc. has developed a unique Vacuum Plasma Spraying (VPS) near-net-shape forming process for the production of multilayered free-standing components. Initial evaluation on the feasibility of applying this process for the production of gas turbine engine components has been performed. The VPS near-net-shape forming process consists of: selecting an appropriate mold material; preconditioning of mold surface ; depositing metallic, ceramic, or composite layers ; and removing mold from the spray-formed structure. The near-net-shape components are heat treated to improve their mechanical properties. A suitable heat treatment cycle was developed for the VPS-applied superalloy. Much of the recent improvements in gas turbine engine performance has been attributed to the introduction of thermal barrier coatings (TBC) for superalloy components. There exist, however, some limitations in current fabrication methods for closed hot-section components: less than ideal coating quality; welding; limited choice of superalloy material; etc... PyroGenesis has used VPS near-net-shape forming to fabricate closed components with an yttria-stabilized-zirconia inner layer, CoNiCrA1Y bond coat, and IN-738LC outer layer. The results from the initial study demonstrate the feasibility of producing near-net-shape components with good coating structures, superior superalloy materials, and the absence welds. The mold was reusable after minor surface conditioning. The TBC showed uniform thickness and microstructure with a smooth surface finish. The bond coat and structural superalloy layers were very dense with no signs of oxidation at the interface. After heat treatment, the mechanical properties of the IN-738LC compare favourably to cast materials.

Numerical Simulation on Thixocasting Process of Auto Box-Like

2011 ◽  
Vol 341-342 ◽  
pp. 177-182 ◽  
Author(s):  
Van Luu Dao ◽  
Sheng Dun Zhao ◽  
Wen Jie Lin ◽  
Yu Qiu Chen
Keyword(s):  
Main Process ◽  
Forming Process ◽  
Billet Temperature ◽  
Forming Technology ◽  
Initial Billet ◽  
Near Net Shape ◽  
Net Shape Forming ◽  
Ram Speed ◽  
Semi Solid ◽  
The Impact

Semi-solid metal processing (thixoforming) is a potential forming technology, which can realize near-net-shape forming process with good quality in one forming step. In this study, semi-solid casting (thixocasting) was used to form the auto box-like. Based on Power Law Cut-Off (PLCO) model and finite element code Procast software, the thixocasting process was modeled and simulated. The impact of main process parameters such as initial billet temperature, ram speed as well as die temperature on the thixocasting process was studied. The results show that thixocasting process can be used in forming auto box-like.

A new near net-shape forming process for alumina

1998 ◽  
Vol 79 (1-3) ◽  
pp. 125-132 ◽  
Author(s):  
Teisuke Sato ◽  
Tatsuo Besshi ◽  
Masatomo Matsui
Keyword(s):  
Forming Process ◽  
Near Net Shape ◽  
Net Shape Forming

scholarly journals Experimental Study on Viscosity and Phase Segregation of Al–Si Powders in Microsemisolid Powder Forming

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Yufeng Wu ◽  
Gap-Yong Kim ◽  
Iver E. Anderson ◽  
Thomas A. Lograsso
Keyword(s):  
Shear Rate ◽  
Phase Segregation ◽  
Heating Time ◽  
Extrusion Ratio ◽  
Semisolid State ◽  
Bulk Materials ◽  
Forming Process ◽  
Near Net Shape ◽  
Net Shape Forming ◽  
Powder Forming

Semisolid powder forming is a promising approach for near-net shape forming of features in macro-/microscale. In this paper, viscosity and phase segregation behavior of Al–Si powders in the semisolid state were studied with back extrusion experiments. The effects of process parameters including shear rate, extrusion ratio, heating time, and precompaction pressure were analyzed using the design of experiments method. The results showed that the effects of shear rate, extrusion, ratio and heating time were statistically significant factors influencing the viscosity. The semisolid state powders showed a shear thinning behavior. Moreover, microstructure analysis of extruded parts indicated severe phase segregation during the forming process. As the extrusion opening became small (∼400 μm), the phase segregation increased. This study expanded the semisolid processing technology by exploring the use of powdered materials instead of typical bulk materials for applications in micro-/mesomanufacturing. Replacing bulk materials with powdered materials may add a new dimension to the technique by allowing tailoring of material properties.

Near net shape forming process of a titanium alloy impeller

2007 ◽  
Vol 187-188 ◽  
pp. 582-585 ◽  
Author(s):  
K. Shi ◽  
D.B. Shan ◽  
W.C. Xu ◽  
Y. Lu
Keyword(s):  
Titanium Alloy ◽  
Forming Process ◽  
Near Net Shape ◽  
Net Shape Forming

Near Net Shape Forming Process of a Titanium Alloy Component Using Hot Isostatic Pressing with Graphite Mould

2014 ◽  
Vol 599-601 ◽  
pp. 81-87
Author(s):  
Peng Ju Xue ◽  
Yan Wu ◽  
Jun Huang ◽  
Qing Song Wei ◽  
Yu Sheng Shi ◽  
...  
Keyword(s):  
Mild Steel ◽  
Hot Isostatic Pressing ◽  
Free Layer ◽  
Forming Process ◽  
Machined Surface ◽  
Isostatic Pressing ◽  
Isolation Layer ◽  
Near Net Shape ◽  
Net Shape Forming ◽  
Graphite Mould

Ti6Al4V component has been formed by hot isostatic pressing (HIPping) using internal graphite mould with Ni isolation layer. The shape of the graphite had no deformation after HIPping. The Ni isolation layer with a thickness of approximately 5μm on graphite before HIPping was diffused into the dense Ti6Al4V component surface and formed a uniform, compact and crack free layer with a thickness of approximately 100μm after HIPping. The Ni diffusion layer is not damaged after removing the graphite mould by unpolluted sandblasting. The interface topography and the elements diffusion have been assessed and it is found that the non-machined surface of Ti6Al4V component was improved by using graphite mould than those used mild steel. The roughness of non-machined surface after removing the graphite mould by sandblasting is Ra=1.6μm, and the roughness of non-machined surface after removing the mild steel by acid pickling is Ra=10.8μm. It is concluded that graphite mould could be used for the HIPping process to produce complex-shaped components.

Titanium Alloys Casting for Structural Application

2007 ◽  
Vol 124-126 ◽  
pp. 1449-1452
Author(s):  
Si Young Sung ◽  
Bong Jae Choi ◽  
Young Jig Kim
Keyword(s):  
Titanium Alloys ◽  
Formation Mechanism ◽  
Pure Titanium ◽  
Melting Furnace ◽  
Metal Mold ◽  
Tial Alloys ◽  
Structural Application ◽  
Arc Melting ◽  
Alpha Case ◽  
Net Shape Forming

The aim of this study is to clarify the metal-mold reaction for the economic net-shape forming of titanium and titanium alloys. The metal-mold reactions between pure titanium, TiAl alloys and Al2O3 mold were examined in a plasma arc melting furnace. The alpha-case generation between pure titanium and Al2O3 mold could not be explained by the conventional α-case formation mechanism, which is known to be formed by the interstitials, especially oxygen dissolved from mold materials. However, based on the interstitial and substitutional α-case formation mechanism, the α-case formation between pure titanium and Al2O3 mold, and α-case free casting of TiAl alloys against Al2O3 mold can be explained. On the basis of the interstitial and substitutional α-case formation mechanism, α-case controlled net-shape forming of titanium and TiAl alloys can be possible for the structural materials.

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