共查询到19条相似文献,搜索用时 62 毫秒
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不锈钢粉末冷等静压数值模拟与实验验证 总被引:2,自引:0,他引:2
通过冷等静压实验获得了不锈钢粉末的压力-密度关系,在模拟中用于表征材料的硬化特性。为了描述粉末的致密化行为,使用了ABAQUS有限元软件中的Cam-Clay模型,对粉末的冷等静压实验过程进行模拟,结果表明实验的尺寸与模拟的结果符合得较好,说明模拟中使用的参数设置是合理的。然后使用选择性激光烧结/冷等静压复合工艺制造球形制件,并对冷等静压过程进行模拟,结果表明制件变形比较均匀,实验的结果与模拟的结果符合得较好,密度的预测与实验结果比较吻合。通过模拟不仅为冷等静压工艺提供有益的指导,也为以后复杂试样的冷等静压尺寸设计提供了重要参考。 相似文献
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研究了一种快速凝固高温钛合金粉末热等静压(HIP)成形的致密化过程及其机制。当HIP成形温度低于500℃时,快速凝固高温钛合金粉末的颗粒相互靠近并重排,相对致密度由64.5%提高到81%,粉末颗粒间为点接触,没有发生明显的塑性变形;当HIP成形温度提高到500-700℃时,粉末颗粒发生显著的塑性变形,相对致密度迅速提高到97%;当HIP成形温度高于700℃后,粉末颗粒间的接触面较大,几何强化效应显著,外界压力不足以使粉末进一步变形,粉末体通过扩散蠕变完成致密化。 相似文献
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测量并推算了盘件用FGH95合金的比热容等物理性能,用反推法计算了得到了热交换系数的函数计算公式,模拟计算了FGH95粉末高温合金锻件的温度和淬火应力场,并与实测值进行了对比,结果相符。计算并实测了不同冷速下FGH95合金的力学性能。本研究结果对实际热处理工艺具有实际意义。 相似文献
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为解决弹体旋压生产中参数难以选择的问题,基于弹塑性有限元基本理论,综合考虑旋压过程中金属在3个方向的流动以及摩擦等实际情况,建立了某导弹弹体某舱段旋压加工的三维弹塑性有限元力学数值模型,研究了几种关键工艺参数(包括旋轮圆角半径、进给速度、每道次减薄率等)对旋压成形结果的影响规律。 相似文献
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纳米晶W-Cu合金粉体的冷压成形研究 总被引:9,自引:0,他引:9
研究了纳米晶W-Cu微粉在模压及冷等静压工艺下成形特性的对比,试验证明600MPa压力下,冷等静压工艺较模压工艺获得的坏体致密度高于15%,但冷等静压工艺中的包套除气对坯体致密及性能有较大的影响。 相似文献
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《Advanced Powder Technology》2022,33(2):103411
In this work, near-net-shape powder metallurgy hot isostatic pressing (NNS PM HIP) of Ni-base metal matrix composite (Ni-MMC) was developed to improve the hardness and wear properties of turbopumps mechanical seals. Silicon carbide (SiC) and titanium diboride (TiB2) fine powders were used as reinforcements with different ratios to improve the hardness and consequently the tribological properties of the developed Ni-MMC material. Powder characterisation was performed on the blended powders to check the homogeneity of the mixed powders. The hot isostatically pressed (HIPed) Ni-MMC microstructures were analysed using scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) techniques. The HIPed material showed a fully dense microstructure with a continuous network of ceramic reinforcement particles at the prior particle boundaries (PPBs). Furthermore, microhardness tests were performed on IN625, IN625-SiC and IN625-TiB2 to understand the impact of the reinforcement on the microhardness. It was demonstrated that the volume percentage of ceramic reinforcement in the IN625 matrix plays a crucial role in achieving higher hardness by increasing the fraction of hard phases appearing in the microstructure of the developed Ni-MMC material. The final part of the work focuses on the canister design and manufacture of a near-net-shape (NNS) mechanical gas seal using IN625 based MMC to demonstrate the feasibility of manufacturing mechanical seals through the NNS PM HIP technique. Overall, IN625 based MMCs resulted in a drastic improvement in tribological properties if compared to the base material. Furthermore, the employment of the PM HIP consolidation technique resulted in a fully dense and homogeneous microstructure, highlighting the potentials of PM HIP in the generation of novel composite materials. 相似文献
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Ti-6Al-4V couples have been diffusion bonded by hot isostatic pressing (HIPping) after vacuum brazing was used to seal the periphery of the bonding samples so that no encapsulation was required during HIPping. Analytical scanning electron microscopy was used to assess the microstructure of the HIPped interface and tensile and fatigue properties of bonded samples were compared with those of the bulk starting material. The tensile properties of the bonds were shown to be comparable with those of the bulk material, but the fatigue life was slightly downgraded. The fatigue fractures were initiated by inclusions on the bonding interface, caused by contamination before bonding, but the fatigue cracks did not propagate along the bonding interface indicating a strong bond. It is concluded that this technique of vacuum brazing plus HIPping could be used for encapsulation-free HIPping to produce complex-shaped components. 相似文献
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《Advanced Powder Technology》2021,32(10):3610-3623
Achieving the near-net shaping of brittle and difficult-to-machine materials is still challenging. Thus, we explore a method to prepare Ti-22Al-25Nb alloy by solid-powder hot isostatic pressing (HIP) diffusion bonding. The grain size, microstructure, interface features and mechanical properties of the fabricated alloy were systematically investigated. The results show that the solid-powder interface realizes a complete metallurgical bonding, and the grain size, composition and microstructure in transition zone is formed on the side of preform through recrystallization. There is a huge difference for the grain size between the powder forming zone and the preforming zone. As a result, the fabricated sample for solid-powder transition zone exhibits an excellent mechanical properties, with a tensile strength of 940 MPa, elongation of 2.9% and torsional strength of 815 MPa, respectively. In response to the torsional force, the crack starts from the preforming zone, and the crack deflection and branching occurs in the transition zone, thereby preventing the crack from propagating to the powder forming zone. The torsional strength of the solid powder HIP diffusion bonding zone is basically the same as that of the preformed zone. This study proposes a new solution for fabricating brittle and difficult-to-process materials and is of great significance in the development of the overall near-net shaping technology for complex components of such material. 相似文献
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镍基铸造高温合金是航空发动机与燃气轮机生产制造过程中应用的主要材料之一,在航空航天、能源工业、船舶舰艇等领域有着广泛的应用。现代航空工业的飞速发展离不开高温合金综合性能的快速提升,而热等静压技术在镍基铸造高温合金领域的应用对镍基铸造高温合金综合性能的改进方面发挥了举足轻重的作用。本文介绍了热等静压技术的工作原理与应用发展历史,总结了热等静压技术在镍基铸造高温合金领域的研究应用现状,重点阐述了热等静压技术对铸造高温合金的致密化作用机理与组织性能影响、热等静压对长期服役镍基铸造高温合金组织修复研究以及实现两种镍基高温合金扩散连接的应用优势与研究成果。同时指出热等静压技术研究中存在的一些问题及国内热等静压技术在镍基铸造高温合金领域的发展趋势。 相似文献
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M. N. Rahaman R. E. Dutton S. L. Semiatin 《Materials Science and Engineering: A》2003,360(1-2):169-175
A method is described for the fabrication of dense thin sheets of γ titanium aluminide (γ-TiAl) by a powder metallurgy route involving hot isostatic pressing (HIP) of tape-cast monotapes. Gamma-TiAl powder (particle size <90 μm) was incorporated into a concentrated slurry by mixing with an organic binder in a solvent and the system was tape-cast to form sheets with a thickness of 400–600 μm. After insertion of the tape-cast sheet into a HIP can and binder removal in situ by thermal decomposition, HIP at 1100 °C under a pressure of 130 MPa produced dense sheets with a thickness of 250–400 μm. The free, dense sheets with a fine-grain microstructure were obtained by dissolution and oxidation of the HIP can. The carbon content of the fabricated sheets was 0.035 wt.%. Facile adaptation of the process to the production of γ-TiAl thin sheets with complex shapes is expected. 相似文献
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《Optical Materials》2014,36(12):2405-2410
The Nd:YAG transparent ceramics were fabricated by vacuum sintering. The Nd:YAG samples were annealed at 1450 °C for 20 h in air and followed by hot isostatic pressing (HIP) at 1700 °C for 2 h in 200 MPa Ar and then re-annealed at 1250–1450 °C for 10 h in air. The experimental results showed that the optical properties of Nd:YAG samples varied markedly with different post treatments. After air annealing at 1450 °C for 20 h and HIP at 1700 °C for 2 h under 200 MPa of Ar and then air re-annealing at 1250 °C for 10 h, the transmittances of the samples increased from 51.2% to 77.2% (at 400 nm) and 78.4% to 83.6% (at 1064 nm), respectively. The annealing and HIP are effective post treatments to reduce oxygen vacancies and intergranular pores respectively in Nd:YAG transparent ceramics. 相似文献