To investigate the effects of pressure on the hot isostatic pressing(HIP) process of a stainless steel powder,density distribution and deformation of the powder at four different applied pressure levels were predicted...To investigate the effects of pressure on the hot isostatic pressing(HIP) process of a stainless steel powder,density distribution and deformation of the powder at four different applied pressure levels were predicted and compared by using finite element method(FEM).Constitutive relations of porous compacts during HIP process were derived based on the yield criterion of porous metal materials.Thermo-mechanical coupling calculations were carried out by the MSC.Marc.Densification mechanisms were studied through evolutions of relative density,equivalent plastic strain and equivalent viscoplastic strain rate for compacts.The simulation results were also compared with experimental data.The results show that the densification rate and final density of compacts increase dramatically with the increase in the applied pressure level when it is below 100 MPa during HIP process,and the creep for compacts evolves into steady stage with the improvement of density.展开更多
The NiAl-28Cr-5.85Mo-0.15Hf alloy was prepared by high-pressure die casting (HPDC) and subsequent hot isostatic pressing(HIP), and tested for compressible strength and fracture behavior at 300-1 373 K. The results sho...The NiAl-28Cr-5.85Mo-0.15Hf alloy was prepared by high-pressure die casting (HPDC) and subsequent hot isostatic pressing(HIP), and tested for compressible strength and fracture behavior at 300-1 373 K. The results show that the elevated temperature 0.2% compressible yield strength as well as the room-temperature compressible fracture strain of as-HIP alloy are larger than those of the same alloy prepared by directional solidification (DS). It suggests that the fine structures with a homogeneous distribution of fine Cr (Mo) and Hf-rich phase created by high-pressure die casting lead to these improvements.展开更多
Blended elemental Ti 34%Al powders (mass fraction), containing 1.5%TiC, were hot isostatic pressed to prepare TiAl alloys. The effects of HIPing pressure on the sintered density, microstructure, constitutions phase we...Blended elemental Ti 34%Al powders (mass fraction), containing 1.5%TiC, were hot isostatic pressed to prepare TiAl alloys. The effects of HIPing pressure on the sintered density, microstructure, constitutions phase were studied in details. The results show that the density of TiAl alloy increases repaidly with the increase of the HIPing pressure. At the same time, with the increase of pressure, the Ti 3Al phase in matrix disappears. TiC reacts with other substance, forming Ti 2AlC phase, which precipitates at grain boundaries. With the increase of hot isostatic pressing(HIPing) pressure, the shrinkage of the alloys increases, the fine spherical Ti 2AlC phase can meet together and forms a needle shape Ti 2AlC, and the amount of needle shaped Ti 2AlC phase increases. The composite material of TiAl containing C can be made easily by HIPing technology.展开更多
Bodycote researchers have successfully demonstrated that a T6 heat treatment can be integrated with Densal?, a proprietary, aluminum specific, hot isostatic pressing (HIP) process. In this combined operation, at least...Bodycote researchers have successfully demonstrated that a T6 heat treatment can be integrated with Densal?, a proprietary, aluminum specific, hot isostatic pressing (HIP) process. In this combined operation, at least a portion of the solution heat treatment is conducted at elevated pressure. During development, two issues, adiabatic cooling during depressurization and a possible variation in the kinetics of homogenization resulting from conducting the solution heat treat at elevated pressure were perceived as factors which could alter the heat treat response from that seen in conventional processing. This paper reviews the results of experiments performed to Al-Si-Mg (A356.0) castings subjected to both combined and conventional processing routes. Results indicate that the combined HIP and heat treat process is an efficient means of achieving a microstructure characteristic of a conventionally T6 processed material while eliminating porosity within the casting. Further, the fatigue life of an A356.0 casting processed using the combined cycle can be improved by more than an order of magnitude over the as-cast and T6 treated component.展开更多
讨论了直接热等静压至近净形(HIP-NNS:Hot lsostatic Pressing to Near-Not-Shape)工艺在铍光镜制造中的应用。HIP-NNS工艺具有快速一步成形、机加工量小、成本低等优点,尤其适用于昂贵、质脆、剧毒铍这一特殊材料的固结。与传统真空热...讨论了直接热等静压至近净形(HIP-NNS:Hot lsostatic Pressing to Near-Not-Shape)工艺在铍光镜制造中的应用。HIP-NNS工艺具有快速一步成形、机加工量小、成本低等优点,尤其适用于昂贵、质脆、剧毒铍这一特殊材料的固结。与传统真空热压法相比,由该工艺制得的单块轻型网状铍光镜消除了热膨胀系数的各向异性和不均匀性,从而进一步促进铍光镜的广泛应用。展开更多
粉末冶金热等静压近终(净)成形(powder metallurgy hot isostatic pressing to near-not-shape,PM-HIP-NNS)技术用于制备高性能的复杂零部件,在粉末冶金行业具有广阔的应用前景,其致密化过程有特殊的力学行为,需要与数值模拟相结合,以...粉末冶金热等静压近终(净)成形(powder metallurgy hot isostatic pressing to near-not-shape,PM-HIP-NNS)技术用于制备高性能的复杂零部件,在粉末冶金行业具有广阔的应用前景,其致密化过程有特殊的力学行为,需要与数值模拟相结合,以便减少实验过程中试错法造成的物力、财力浪费。本文基于热-弹塑性-蠕变-相对密度耦合本构模型,对SS316L粉体材料在SS304钢包套材料中的压制过程进行了有限元数值模拟,探究热等静压(hot isostatic pressing,HIP)过程中粉末密度场、温度场以及应力场的变化。结果表明:高温高压下金属粉末成形规律的数值模拟与试验相吻合,证实模型可以合理预测金属粉末在高温高压下的变形行为,为粉末HIP工艺优化提供了重要依据。展开更多
基金Project(2007AA03Z115) supported by the National High Technology Research and Development Program of ChinaProject(2009ZX04005-041-03) supported by the National Science and Technology Major Program of ChinaProject(2010MS046) supported by the Independent Fund of Huazhong University of Science and Technology,China
文摘To investigate the effects of pressure on the hot isostatic pressing(HIP) process of a stainless steel powder,density distribution and deformation of the powder at four different applied pressure levels were predicted and compared by using finite element method(FEM).Constitutive relations of porous compacts during HIP process were derived based on the yield criterion of porous metal materials.Thermo-mechanical coupling calculations were carried out by the MSC.Marc.Densification mechanisms were studied through evolutions of relative density,equivalent plastic strain and equivalent viscoplastic strain rate for compacts.The simulation results were also compared with experimental data.The results show that the densification rate and final density of compacts increase dramatically with the increase in the applied pressure level when it is below 100 MPa during HIP process,and the creep for compacts evolves into steady stage with the improvement of density.
基金Project (05YB31) supported by the Scientific Research Initial Foundation for Doctor of Shenyang Institute of Aeronautical Engineering,China
文摘The NiAl-28Cr-5.85Mo-0.15Hf alloy was prepared by high-pressure die casting (HPDC) and subsequent hot isostatic pressing(HIP), and tested for compressible strength and fracture behavior at 300-1 373 K. The results show that the elevated temperature 0.2% compressible yield strength as well as the room-temperature compressible fracture strain of as-HIP alloy are larger than those of the same alloy prepared by directional solidification (DS). It suggests that the fine structures with a homogeneous distribution of fine Cr (Mo) and Hf-rich phase created by high-pressure die casting lead to these improvements.
文摘Blended elemental Ti 34%Al powders (mass fraction), containing 1.5%TiC, were hot isostatic pressed to prepare TiAl alloys. The effects of HIPing pressure on the sintered density, microstructure, constitutions phase were studied in details. The results show that the density of TiAl alloy increases repaidly with the increase of the HIPing pressure. At the same time, with the increase of pressure, the Ti 3Al phase in matrix disappears. TiC reacts with other substance, forming Ti 2AlC phase, which precipitates at grain boundaries. With the increase of hot isostatic pressing(HIPing) pressure, the shrinkage of the alloys increases, the fine spherical Ti 2AlC phase can meet together and forms a needle shape Ti 2AlC, and the amount of needle shaped Ti 2AlC phase increases. The composite material of TiAl containing C can be made easily by HIPing technology.
文摘Bodycote researchers have successfully demonstrated that a T6 heat treatment can be integrated with Densal?, a proprietary, aluminum specific, hot isostatic pressing (HIP) process. In this combined operation, at least a portion of the solution heat treatment is conducted at elevated pressure. During development, two issues, adiabatic cooling during depressurization and a possible variation in the kinetics of homogenization resulting from conducting the solution heat treat at elevated pressure were perceived as factors which could alter the heat treat response from that seen in conventional processing. This paper reviews the results of experiments performed to Al-Si-Mg (A356.0) castings subjected to both combined and conventional processing routes. Results indicate that the combined HIP and heat treat process is an efficient means of achieving a microstructure characteristic of a conventionally T6 processed material while eliminating porosity within the casting. Further, the fatigue life of an A356.0 casting processed using the combined cycle can be improved by more than an order of magnitude over the as-cast and T6 treated component.
文摘讨论了直接热等静压至近净形(HIP-NNS:Hot lsostatic Pressing to Near-Not-Shape)工艺在铍光镜制造中的应用。HIP-NNS工艺具有快速一步成形、机加工量小、成本低等优点,尤其适用于昂贵、质脆、剧毒铍这一特殊材料的固结。与传统真空热压法相比,由该工艺制得的单块轻型网状铍光镜消除了热膨胀系数的各向异性和不均匀性,从而进一步促进铍光镜的广泛应用。
文摘粉末冶金热等静压近终(净)成形(powder metallurgy hot isostatic pressing to near-not-shape,PM-HIP-NNS)技术用于制备高性能的复杂零部件,在粉末冶金行业具有广阔的应用前景,其致密化过程有特殊的力学行为,需要与数值模拟相结合,以便减少实验过程中试错法造成的物力、财力浪费。本文基于热-弹塑性-蠕变-相对密度耦合本构模型,对SS316L粉体材料在SS304钢包套材料中的压制过程进行了有限元数值模拟,探究热等静压(hot isostatic pressing,HIP)过程中粉末密度场、温度场以及应力场的变化。结果表明:高温高压下金属粉末成形规律的数值模拟与试验相吻合,证实模型可以合理预测金属粉末在高温高压下的变形行为,为粉末HIP工艺优化提供了重要依据。
