Compaction of Ti-6Al-4V Powder by ECAE with Back-Pressure

2007 ◽  
Vol 29-30 ◽  
pp. 33-36 ◽  
Author(s):  
Rimma Lapovok ◽  
Dacian Tomus ◽  
Barry C. Muddle
Keyword(s):  
Powder Metallurgy ◽  
Hydrostatic Pressure ◽  
Relative Density ◽  
Shear Deformation ◽  
Vickers Hardness ◽  
Room Temperature ◽  
Low Cost ◽  
Hot Isostatic Pressing ◽  
Back Pressure ◽  
Angular Pressing

Powder metallurgy is widely used to produce alloys with low cost of production. The main drawback using powders is the level of residual porosity of final product which often implies the application of a complicated and costly hot isostatic pressing process. However, this issue can be overcome by using equal channel angular pressing (ECAE) with back pressure (BP). The use of severe shear deformation, with imposed hydrostatic pressure, allows a reduction in the range of compaction temperatures compare to those used in conventional practice. The compaction of Ti-6Al-4V powder by the ECAE method has been investigated. The compaction has been performed at temperatures starting from room temperature (RT) and increasing up to 400°C with various back pressures ranging from 0 to 350MPa. A billet processed by ECAE with 43MPa back-pressure at 400°C was found to have improved relative density of 97.5% and increased Vickers hardness of 369HV, compared to values of 96.7% and 325HV respectively obtained at RT. A relative density of 98.2% and 426HV hardness were measured for billets processed with BP = 262MPa at 400°C. A fully compact billet was obtained by applying 350 MPa of BP at 400°C.

A Novel Forming Process for Powder Metallurgy of Superalloys

2014 ◽  
Vol 622-623 ◽  
pp. 833-839 ◽  
Author(s):  
Qian Bai ◽  
Jian Guo Lin ◽  
Gao Feng Tian ◽  
Daniel S. Balint ◽  
Jin Wen Zou
Keyword(s):  
Powder Metallurgy ◽  
Relative Density ◽  
High Performance ◽  
Low Cost ◽  
Hot Isostatic Pressing ◽  
Hot Extrusion ◽  
Forming Process ◽  
Isostatic Pressing ◽  
Wide Range ◽  
Forming Temperature

Powder metallurgy (PM) of nickel-based superalloys has been used for a wide range of products owing to their excellent special properties in processing and applications. Typical processes for high performance PM superalloys include hot isostatic pressing, hot extrusion and hot isothermal forging. Hot isostatic pressing is normally conducted at a high temperature, by using a low pressure for a long time in a closed vessel, resulting in high cost and low product efficiency. In this paper a novel forming process, i.e. direct powder forging for powder metallurgy of superalloys has been proposed. In this process, the encapsulated and vacuumed powder is heated up to the forming temperature and forged directly to the final shape, by using a high forming load for a very short time. Direct powder forging is a low-cost and energy-saving process compared to conventional PM processes, and in addition, press machines of conventional forging can be used for direct powder forming process. In direct powder forging it is important to control the relative density of the deformed part since the existence of voids could reduce the mechanical strength and fatigue life. In this paper, feasibility tests of direct powder forging are presented. Microstructure, relative density and hardness of the formed specimen were studied.

scholarly journals Evolution of the Microstructure and Mechanical Properties of a Ti35Nb2Sn Alloy Post-Processed by Hot Isostatic Pressing for Biomedical Applications

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1027
Author(s):  
Joan Lario ◽  
Ángel Vicente ◽  
Vicente Amigó
Keyword(s):  
Powder Metallurgy ◽  
Mechanical Strength ◽  
Room Temperature ◽  
Hot Isostatic Pressing ◽  
Phase Changes ◽  
Post Processing ◽  
Isostatic Pressing ◽  
Porosity Reduction ◽  
Processing Step ◽  
Hip Process

The HIP post-processing step is required for developing next generation of advanced powder metallurgy titanium alloys for orthopedic and dental applications. The influence of the hot isostatic pressing (HIP) post-processing step on structural and phase changes, porosity healing, and mechanical strength in a powder metallurgy Ti35Nb2Sn alloy was studied. Powders were pressed at room temperature at 750 MPa, and then sintered at 1350 °C in a vacuum for 3 h. The standard HIP process at 1200 °C and 150 MPa for 3 h was performed to study its effect on a Ti35Nb2Sn powder metallurgy alloy. The influence of the HIP process and cold rate on the density, microstructure, quantity of interstitial elements, mechanical strength, and Young’s modulus was investigated. HIP post-processing for 2 h at 1200 °C and 150 MPa led to greater porosity reduction and a marked retention of the β phase at room temperature. The slow cooling rate during the HIP process affected phase stability, with a large amount of α”-phase precipitate, which decreased the titanium alloy’s yield strength.

Effect of Annealing Time on Properties of Cr/NbCr2 Alloy

2015 ◽  
Vol 1089 ◽  
pp. 65-69
Author(s):  
Li Ping Deng ◽  
Shi Qiang Lu ◽  
Xuan Xiao ◽  
Ke Lu Wang
Keyword(s):  
Solid Solution ◽  
Plastic Deformation ◽  
Compressive Strength ◽  
Relative Density ◽  
Vickers Hardness ◽  
Annealing Time ◽  
Room Temperature ◽  
Compression Tests ◽  
Compression Properties ◽  
Maximum Value

Cr/NbCr2 alloy containing with 91at.%Cr and 9at.% Nb was prepared by mechanical alloying and hot pressing .Then it was annealing at 1200°C for10h, 30h,50h,100h ,respectively in vacuum condition. The results show that the relative density of Cr/NbCr2 alloy increases slightly with the annealing time. Meanwhile, Vickers hardness of Cr/NbCr2 alloy decreases with the annealing time. After annealing at 1200 °C for 100 h, the relative density and Vickers hardness of Cr/NbCr2 alloy vary from 98.9% to 99.7% and 5.6 GPa to 3.78 GPa, respectively. Due to the good plasticity of chromium solid solution, obvious plastic deformation appears during room temperature compression tests. After annealing at 1200°C for 10h, the compression properties of Cr/NbCr2 alloy, such as compressive strength, yield strength and strain, get the maximum value.

scholarly journals Microstructure and Mechanical Properties of High Relative Density γ-TiAl Alloy Using Irregular Pre-Alloyed Powder

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 635
Author(s):  
Mengjie Yan ◽  
Fang Yang ◽  
Boxin Lu ◽  
Cunguang Chen ◽  
Yanli Sui ◽  
...  
Keyword(s):  
Relative Density ◽  
Tial Alloy ◽  
Sintering Temperature ◽  
Low Cost ◽  
Hot Isostatic Pressing ◽  
Duplex Structure ◽  
Sintered Compact ◽  
High Relative Density ◽  
Tih2 Powder ◽  
Al Powder

Preparing high relative density γ-TiAl alloy by pressure-less sintering at low-cost has always been a challenge. Therefore, a new kind of non-spherical pre-alloyed TiAl powder was prepared by the reaction of TiH2 powder and Al powder at 800 °C to fabricate high-density Ti-48Al alloy via pressure-less sintering. The oxygen content was controlled to below 1800 ppm by using coarse Al powder (~120 μm). The sintered densities ranged from 92.1% to 97.5% with sintering temperature varying from 1300 °C to 1450 °C. The microstructure of the sintered compact was greatly influenced by the sintering temperature. The as-sintered samples had a near-γ structure at 1350 °C, a duplex structure at 1400 °C, and a nearly lamellar structure at 1450 °C. To achieve full densification, non-capsule hot isostatic pressing was performed on the 1350 °C and 1400 °C sintered samples. As a result, high compressive strengths of 2241 MPa and 1931MPa were obtained, which were higher than the existing Ti-48Al alloys.

Effects of Porosity and Re-HIP on Properties of Ti-6Al-4V Alloy from Atomized Powder

2014 ◽  
Vol 552 ◽  
pp. 274-277 ◽  
Author(s):  
Rui Peng Guo ◽  
Lei Xu ◽  
Jia Feng Lei ◽  
Rui Yang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Powder Metallurgy ◽  
Relative Density ◽  
Hot Isostatic Pressing ◽  
Effective Technique ◽  
Isostatic Pressing ◽  
Porosity Defects

Ti-6Al-4V alloys of various densities were prepared by powder metallurgy (PM) using hot isostatic pressing (HIPing). The effects of porosity on mechanical properties of PM compacts have been investigated. It indicated that PM Ti-6Al-4V alloy exhibited a better performance by increase of relative density, especially for the tensile strength at 400 oC. Re-HIPing was used to assess the possibility for increasing the relative density of PM compacts with porosity defects in the first HIPing cycles. The results show that re-HIPing is an effective technique to heal porosity defects. The relative density of PM compacts with porosity can be significantly improved by re-HIPing.

scholarly journals Evolution of Microstructure and Elements Distribution of Powder Metallurgy Borated Stainless Steel during Hot Isostatic Pressing

Metals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 19
Author(s):  
Yanbin Pei ◽  
Xuanhui Qu ◽  
Qilu Ge ◽  
Tiejun Wang
Keyword(s):  
Grain Size ◽  
Tensile Strength ◽  
Stainless Steel ◽  
Powder Metallurgy ◽  
Relative Density ◽  
Hot Isostatic Pressing ◽  
Elemental Distribution ◽  
Isostatic Pressing ◽  
Average Grain Size ◽  
Borated Stainless Steel

prepared by powder metallurgy process incorporating atomization and hot isostatic pressing (HIP) sintering at six different temperatures from 600 to 1160 °C, borated stainless steel (BSS) containing boron content of 1.86 wt% was studied. The phase of BSS, relative density of different temperature, microstructure, elemental distribution, and mechanical properties were tested and analyzed. The phases of the alloy were calculated by the Thermo-Calc (2021a, Thermo-Calc Software, Solna, Sweden) and studied by quantitative X-ray diffraction phase analysis. The distributions of boron, chromium, and iron in grains of the alloy were analyzed by scanning electron microscopy and transmission electron microscope. The grain size distributions and average grain sizes were calculated for the boron-containing phases at 900, 1000, 1100, and 1160 °C, as well as the average grain size of the austenite phase at 700 and 1160 °C. After undergoing HIP sintering at 900, 1000, 1100, and 1160 °C, respectively, the tensile strength and ductility of the alloy were tested, and the fracture surfaces were analyzed. It was found that the alloy consisted of two phases (austenite and boron-containing phase) when HIP sintering temperature was higher than 900 °C, and the relative density of the prepared alloys was higher than 99% when HIP temperature was higher than 1000 °C. According to the boron-containing phase grain size distribution and microstructure analysis, the boron-containing phase precipitated both inside the austenite matrix and at the grain boundaries and its growth mechanism was divided into four steps. The tensile strength and elongation of alloy were up to 776 MPa and 19% respectively when the HIP sintering was at 1000 °C.

Bulk Mg Produced by Back Pressure Equal Channel Angular Consolidation (BP- ECAC)

2008 ◽  
Vol 584-586 ◽  
pp. 114-118 ◽  
Author(s):  
Xiao Lin Wu ◽  
Wei Xu ◽  
Masahiro Kubota ◽  
Kenong Xia
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Room Temperature ◽  
Vickers Microhardness ◽  
Back Pressure ◽  
Angular Pressing ◽  
Transmission Electron ◽  
Average Size ◽  
Scanning Electron ◽  
Compressive Tests

Bulk magnesium was consolidated from pure Mg particles with an average size of ~59 µm by back pressure equal channel angular pressing. The Mg powder was processed at 200°C for 4 and 8 passes, respectively, using route C. The consolidated materials displayed density of 1.78 g/cm3, compared to the theoretical value of 1.74 g/cm3 for pure Mg. Vickers microhardness (HV) values were measured to be about 54. Compressive tests at room temperature revealed yield strengths of 100-110 MPa and ultimate strengths of up to 142 MPa with strains to fracture of ~9%, comparable to those for extruded pure Mg. Microstructures were examined using optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM).

scholarly journals Evolution of the Microstructure and Mechanical Properties of a Ti35Nb2Sn Alloy Post-Processed by Hot Isostatic Pressing for Biomedical Applications

2021 ◽  
Author(s):  
Joan Lario Femenía ◽  
Angel Vicente Escuder ◽  
Vicente Amigó Borrás
Keyword(s):  
Powder Metallurgy ◽  
Mechanical Strength ◽  
Room Temperature ◽  
Hot Isostatic Pressing ◽  
Phase Changes ◽  
Post Processing ◽  
Slow Cooling ◽  
Isostatic Pressing ◽  
Porosity Reduction ◽  
Hip Process

The influence of the hot isostatic pressing (HIP) post-processing step on structural and phase changes, porosity healing and mechanical strength in a powder metallurgy Ti35Nb2Sn alloy was studied. Powders were pressed at room temperature at 750 MPa, and then sintered at 1,350°C in a vacuum for 3 h. The standard HIP process at 1,200°C and 150 MPa for 3 h was performed to study its effect on a Ti35Nb2Sn powder metallurgy alloy. The influence of the HIP process and cold rate on density, microstructure, the quantity of interstitial elements, mechanical strength and Young's modulus was investigated. HIP post-processing for 2 h at 1,200°C and 150 MPa led to greater porosity reduction and a marked retention of the β phase at room temperature. The slow cooling rate during the HIP process affected phase stability, with a large amount of α”-phase precipitate, which decreased the titanium alloy’s yield strength.

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