Inconel718合金金属注射成形制备过程及力学性能

以Inconel718气雾化预合金粉末为原料,采用金属注射成形(MIM)工艺制备Inconel718合金材料.研究Inconel718合金烧结、热等静压(HIP)、热处理对合金显微组织、密度和力学性能的影响.结果表明:经1275 ℃烧结后,烧结体的相对密度达到98%.烧结体经HIP处理后,达到全致密.经烧结+HIP+热处理后,组织弥散析出了大量的γ″相和γ′相,其室温抗拉强度为1250 MPa,延伸率为21.7%;650 ℃抗拉强度为1177 MPa,延伸率为16.6%,其达到或超过了同牌号锻造合金的性能.     

热处理对Inconel718合金组织及力学性能的影响

针对Inconel 718合金的不同用途,分析研究了4种常用热处理工艺对Inconel 718合金组织和力学性能的影响。结果表明:固溶温度超过1020℃时,奥氏体晶粒显著长大。合金中主要析出相有MC、δ、γ’和γ″相。δ相沿晶界分布,1025℃固溶时呈颗粒状少量析出;950℃固溶时呈块状大量析出;直接时效时呈网状不连续分布。同时,δ相对合金的晶粒度影响较大,且其析出数量和形态决定了合金的韧塑性,γ″、γ’相的析出量和尺寸与晶粒尺寸决定了合金的强度变化。     

Mechanical and tribological behaviors of graphene/Inconel 718 composites

Graphene/Inconel 718 composites were innovatively synthesized through selective laser melting, and the mechanical and tribological performances of the grapheme-reinforced Inconel 718 matrix composites were evaluated. The composite microstructures were characterized by XRD, SEM and Raman spectroscopy. The results show that selective laser melting is a viable method to fabricate Inconel 718 matrix composite and the addition of graphene nanoplatelets leads to a significant strengthening of Inconel 718 alloy, as well as the improvement of tribological performance. The yield strength and ultimate tensile strength of 1.0% graphene/Inconel 718 composites (mass fraction) are 42% and 53% higher than those of pure material, and the friction coefficient and wear rate are 22.4% and 66.8% lower than those of pure material. The decrease of fraction coefficient and wear rate is attributed to the improved hardness of composites and the formation of graphene nanoplatelet protective layer on the worn surfaces.     

Thermal Properties of Ni-Cr-Si-B-Fe Based Interlayer Material and Its Application in TLP Bonding of IN 718 Superalloy

A new Ni-Cr-Si-B-Fe filler material is prepared for transient liquid-phase (TLP) bonding of Inconel 718 superalloy by mechanical alloying technique. The melting temperature range of the filler material and its activation energy of melting are determined by differential scanning calorimetry technique. The activation energy and melting temperature of the alloy powder decrease with increasing milling time. Inconel 718 alloy was joined via TLP by using the newly developed filler material. The effect of TLP bonding temperature and time on microstructural evolution and mechanical properties of the joint was investigated. Three distinct microstructural regions were observed in the bonding area: isothermal solidification zone consisting of a single-phase solid solution, diffusion affected zone consisting of extensive diffusion-induced precipitates of metallic boride, and unaffected base material. The ultimate shear strength and microhardness of the TLP-bonded joint increase with bonding time and temperature.     

一种改型Inconel718合金的组织与性能的研究

采用化学相分析、显微组织分析和显微硬度测试等方法,研究了一种改型镍基高温合金718A在标准热处理状态的显微组织和力学性能。试验结果表明,原型718合金和改型718A合金的主要析出相皆为γ″、γ′、δ、MC相。在标准热处理状态下,改型718A合金中强化相γ′和γ″的量较原型718合金明显增多,而对于组织稳定性不利的8相的析出量则较718合金少。此外,改型718A合金的显微硬度与原型合金相比有了明显的提高,因此具有广阔的应用前景。     

碳化钨弥散强化铜的高温烧结及高温退火

利用机械合金化与高温烧结方法制备WC弥散强化铜材料，研究了高温烧结温度和烧结时间对复合材料组织和性能的影响。结果表明，WC粒子阻碍着烧结时铜基体体积扩散；WC弥散强化铜材料的最佳烧结工艺是：烧结温度950℃，保温时间2．5h，其软化温度基本保持在900℃左右。     

热处理对粉末冶金Inconel 718高温合金组织及性能的影响

以超高转速等离子旋转电极法(SS-PREP法)制备的高球形度Inconel 718高温合金粉末为原料,采用热等静压(HIP)工艺制备了Inconel 718粉末高温合金,重点研究了热处理制度对合金组织和力学性能的影响.实验结果表明:采用SS-PREP法制得的Inconel 718高温合金粉末粒度分布均匀,球形度良好,具...     

Inconel 718合金在高酸性石油井下工具服役环境中的应力腐蚀开裂行为

利用高温高压釜和有限元技术研究了Inconel 718合金在150℃、3.5 MPa H2S分压、3.5 MPa CO_2分压、含100 g/L Cl~-水溶液中的SCC敏感性。结果表明:在模拟高温高酸性工况下,未发现Inconel 718合金发生点蚀和应力腐蚀开裂。拉扭复合载荷对Inconel 718合金耐蚀性的影响体现在拉扭复合载荷作用下材料产生的Von Mises等效应力对其耐蚀性的影响。     

脉冲激光熔覆Inconel 718涂层热行为数值模拟及其对显微组织的影响

目的 揭示脉冲激光作用下Inconel 718合金涂层凝固传热行为的演化机制,改善涂层中Nb、Mo元素偏析现象,提升Inconel 718合金熔覆涂层的力学性能,为优化Inconel 718熔覆涂层质量提供理论依据。方法 综合考虑物性参数随温度、脉冲激光热源、粉末传输形式,以及凝固过程中相变潜热对涂层凝固热行为的影响,构建脉冲激光熔覆传热模型。基于数值模拟技术和激光熔覆试验,利用VHX-2000电子显微镜对涂层显微组织形态进行分析验证,采用日立SU8010场发式扫描电镜观察分析显微组织和元素偏析情况,并使用显微硬度计测试涂层的硬度值。结果 由数值模拟分析结果可知,脉冲激光涂层的冷却速度、温度梯度、凝固速度均大于连续激光涂层,其枝晶生长细密且No、Mo元素呈弥散分布,显微组织自底向顶以平面晶、胞状枝晶、柱状枝晶、等轴枝晶等形式存在,Laves相的体积分数降低至2.93%,在细晶强化和固溶强化作用下,熔覆涂层的平均显微硬度提升至307HV0.1。结论 脉冲激光涂层热行为数值模拟分析结果符合Inconel 718涂层组织形态快速凝固变化的规律,数值模型可靠。脉冲激光形成的高冷却速度和高温度梯度,能在一定程度上抑制Inconel 718合金涂层中Nb、Mo元素的偏析,离散并细化γ枝晶组织,降低Laves相的体积分数,显微组织在细晶强化和固溶强化双重作用下,提升涂层的力学性能。     

热压工艺参数对WC-Cu基胎体力学性能的影响

在深部钻探中,WC-Cu基金刚石钻头胎体被广泛使用。为了提高钻头使用性能,在同一胎体配方下,采用正交试验方案对热压参数进行设计,并烧制试样进行抗弯强度和显微硬度测试。通过方差和极差分析不同烧结温度(A)、烧结压力(B)、保温时间(C)、冷却方式(D)对金刚石钻头胎体力学性能的影响。试验结果表明:对纯胎体和含金刚石胎体抗弯强度影响的顺序为A>D>B>C;对胎体维氏硬度影响的顺序是A>C>B>D。本次正交试验中的最优理论烧结参数为A₃B₃C₁D₄,即烧结温度为960 ℃、烧结压力为16 MPa、保温时间为3 min、冷却方式为400 ℃保温炉冷。此时,与理论参数最接近的工艺试验结果为:纯胎体抗弯强度为983.33 MPa、硬度为437.40 HV,金刚石胎体试样抗弯强度为525.00 MPa。      

高致密度激光选区熔化Inconel 718合金中的微小孔隙缺陷和拉伸性能

本文采用激光选区熔化技术制备了高致密度Inconel 718合金试样，研究了工艺参数（激光功率，扫描速度）对合金试样致密度的影响规律，分析了孔隙缺陷的形成原因，对比研究了微小孔隙缺陷存在条件下的拉伸性能变化，并比较了热处理对不同致密度合金力学性能影响。实验结果表明：工艺参数的改变决定了激光与粉末相互作用的模式，在较高激光功率、低扫描速度条件下发生了“匙孔”模式，气孔较多，致密度降低；当功率减小或者扫描速度增大会由“匙孔”模式向“热传导”模式转变，气孔较少，致密度会升高；但是当激光功率过小或者扫描速度过大时产生未熔合孔隙缺陷，使得材料的致密度出现大幅度减小的现象。拉伸测试结果表明，激光选区熔化成形Inconel 718合金的强度并不会随着致密度的增大呈严格单调增大的变化趋势，微小孔隙缺陷的形貌、数量和尺寸也会对拉伸性能产生影响。SIDA热处理可以大幅提高激光选区熔化成形Inconel 718合金的显微硬度及抗拉强度，但塑性呈显著降低。     

热处理对WC系钢结合金性能影响的研究

研究的合金是以QRO90优质热作模具钢为基体。以WC为硬质相的钢结合金。研究淬火回火工艺对合金组织和性能的影响。试验表明，淬火回火温度对合金性能有显著影响，合金经1000℃淬火，560℃回火，可以获得抗弯强度、硬度和冲击韧性综合性能优异的合金。     

Rock breaking characteristics of a 3D printing grid-matrix impregnated diamond bit

In order to improve the rock-breaking efficiency in hard rock formations, this paper presents an impregnated diamond bit with a special matrix structure. The grid-shaped matrix is designed to achieve large volume breakage so that the rock breaking efficiency can be greatly improved. The calculated specific pressure on the bottom surface lip of the newly proposed bit increased by 67%, from 68 kgf/cm² to 113 kgf/cm², compared to the conventional impregnated diamond bit. In such case, the grid piece can be effectively pressed into rocks to produce more cracks to effectively break them. In this paper, to study the rock-breaking mechanism of this impregnated diamond bit with grid-shaped matrix (IDBGM), subjected to different grid spacing and rock properties, rock cutting tests were conducted by using a TXCB-5P precision microtome and two 3D-printed grid pieces. The results indicate that the optimum grid spacing is 2 mm, because of the largest-scale cuttings when breaking rock ridges produced by the proposed bit. And the mineral particle size is the dominant factor affecting the height of weakened layer of rock. Besides, the IDBGM can more fully exert its structural advantages when applied to the hard rock layer with larger particle size. At the same time, the monitored real-time electric current is consistent with the above results, and further reveals the rock breaking mechanism characteristic of the IDBGM.     

K418合金表面激光再制造Inconel718高温合金涂层性能研究

针对K418高温合金叶轮高温、高转数工况下形变超差大,再制造成形层力学性能降低的领域研究热点,基于波形可调制脉冲激光优化工艺,再制造Inconel718高温合金成形层。采用金相显微镜、SEM、XRD、EDS、显微硬度计对该合金涂层的显微组织形貌、相结构、界面成分分布、基本力学性能进行研究。结果表明:涂层与基体间为致密的冶金结合,涂层中部为粗大的树枝晶,与激光扫描方面成30o^45o角,由涂层中部到顶部及底部,分别退化为等轴晶和胞状晶;成形层显微硬度为4100~4400 MPa,略高于基体;晶内及晶间析出少量Laves相,减少了对成形层硬脆性的影响;摩擦磨损系数较基体略有降低,但仍符合再制造要求。     

A research on WC–8Co preparation by microwave sintering

The microwave sintering technique has been used in WC–Co alloy preparation for many years. The properties of the alloy can be improved using the microwave method even in a very short processing cycle. In this work, the influencing factors of the heating rate on WC–8Co hard metal during the microwave processing were discussed by using a multi-mode high temperature furnace. The experimental results demonstrate that the assisted materials principally contribute to heat insulation, rather than heating. Our results show that, when the temperature exceeds 1100 °C, the heating rate of Co compact slows down and displays slight fluctuations. Porosity of the compacts is shown to have little effect on the heating rate. Further, the special microstructure (overall even and local uneven) of the microwave-prepared WC–8Co alloy is discussed. Besides, the relationships between the microstructure and the mechanical properties of microwave-prepared WC–8Co are explored.     

超细硬质合金WC-10Co-0.8(VC/Cr_3C_2)的烧结特征

超细硬质合金粉末粒度细小,具有高的比表面积和缺陷密度,因而具有较高的烧结活性,呈现出与普通硬质合金不同的烧结特征。因此,针对超细硬质合金特点制定合适的烧结工艺在生产超细硬质合金中是至关重要的。真空烧结超细硬质合金WC-10Co-0.8(VC/Cr3C2)的结果表明:1320℃烧结温度下的超细硬质合金,较1350℃和1380℃的密度和硬度低,WC晶粒细而孔隙度高。1350℃比1380℃具有更高的横向断裂强度(TRS)。WC-10Co-0.8(VC/Cr3C2)超细硬质合金的适宜烧结温度为1350℃。差热分析(DTA)对烧结过程中的热效应分析表明:出现液相温度为950℃,1300℃结束。同时氧化杂质被还原导致质量的损失和气体的产生。晶粒长大抑制剂VC和Cr3C2的加入,提高了氧化物杂质还原温度。     

TiCp／W复合材料的制备工艺与力学性能

研究了烧结温度,烧结保温时间和烧结压力等工艺参数对各３０％ＴｉＣ（体积分数,下同）颗粒的钨基复合材料的力学性能的影响,得到了制备３０％ＴｉＣｐ／Ｗ复合材料的优化的热压烧结工艺为：２０００℃,２０ＭＰａ压力下烧结６０ｍｉｎ,用优化工艺制备的３０％ＴｉＣｐ／Ｗ复合材料的高温强度比其室温强度要高,这种极好高温强度主要是由于Ｗ基体随温度上升发生了由脆性到塑性的转变,使ＴｉＣ颗粒的增强效果在高温得以充分发挥     

Cold Spray Forming of Inconel 718

Inconel 718 was cold spray formed to a 6-mm thickness on an 8-cm diameter aluminum alloy tube using Sulzer Amdry 1718 powder and the Plasma Giken PCS-1000 cold spray system. The effects of spray particle velocity and post-spray heat treatment were studied. Post-spray annealing was performed from 950 to 1250 °C for 1-2 h. The resulting microstructures as well as the corresponding mechanical properties were characterized. As-sprayed coatings exhibited very low ductility. The tensile strength and ductility of the heat-treated coatings were improved to varying levels depending on the heat-treatment and spray conditions. For coatings sprayed at higher particle velocity and heat treated at 1250 °C for 1 h, an elongation of 24% was obtained. SEM micrographs showed a higher fraction of interparticle metallurgical bonds due to some sintering effect. Corresponding fracture surfaces also revealed a higher fraction of dimple features, typically associated with ductile fracture, in the annealed coatings. The results demonstrate that cold spray forming of Inconel 718 is feasible, and with appropriate heat treatment, metallurgical bonding can be increased. The ductility of the spray-formed samples was comparable to that of the bulk material.     

提高金刚石钻头耐磨性和降低烧结温度的试验研究

目前，大多数金刚石钻头采用粉末冶金热压疗法烧结，热压法普遍存在烧结温度较高，对金刚石的原始强度产生不利的影响，也直接影响钻头的质量。同时，胎体配方还比较单一．钻头的耐磨性能不理想，在强研磨性岩层或破碎岩层中钻进寿命较低：这两方面的问题有待进一步研究解决。本文针对这两个问题，采用正交设计方法，在胎体材料中通过加入磷与硼元素，进行了有益的试验研究。结果表明：烧结温度有所下降，钻头的性能有了提高。     

Effect of Heat Treatment on the Microstructure and Mechanical Properties of the Modified 718 Alloy

M718 alloy with an extra high Mo content of 7.50 wt% which reduced Nb addition and increased Al and Ti additions within the composition specifications of 718 alloy has been designed to increase the service temperature of 718 alloy. And the effect of the heat treatment on the microstructure and mechanical properties of M718 alloy has been investigated in this study. The results showed that Laves phase precipitated on the grain boundaries of M718 alloy instead of d-Ni_3 Nb phase in718 alloy, and y'and y'phases precipitated in the matrix of M718 alloy as that in 718 alloy. Increasing the solution temperature from 960 to 1050 ℃ noticeably reduced the intergranular precipitation of Laves phase. The precipitation of Laves phase was appropriate at 1020 ℃ for improving the grain boundary cohesion. Increasing the two-stage aging temperatures markedly increased the sizes of y' andy'phases. As a result, the strength of M718 alloy increased.