INCONEL 718合金组织失稳及提高组织稳定性研究

采用电镜分析为主要手段并结合相应的力学性能作为强化和脆化的评判特征,以研究当今世界上最广泛应用的高温合金INCONEL718在高温长期时效过程中的相转变规律为出发点,以分析合金组织失稳的本质为依据,为发展新一代高组织稳定性的改型合金提出方向。 将合金在593～704℃的广宽温度范围内进行1000～50000h的长期时效。研究结果表明,合金强化失效不仅在于主要强化相γ″和γ′的聚集长大,以及γ″向稳定的δ相的转变,而且晶界σ相的析出是合金脆化的主要原因。 选用实际运行了28000h从齿顶到齿根具有温度梯度(为650～450℃)的涡轮盘榫齿作为高温长期应力时效下的试验分析材料。提出了应力明显诱发合金中的γ″ δ相变过程,并认为γ″ δ相的转变是高温长期使用过程中组织失稳而导致强化程度减弱的主要原因。同时完整地阐述了INCONEL718合金中γ″ δ的相变机制,提出了这种相变的模型。 在了解了合金失稳的本质的基础上,对合宜地调整主要强化元素Nb、Ti和Al的含量及比例,以企提高组织稳定性等进行了系统的研究。最后,提出了改型合金含后发展的方向及高组织稳定性改型合金的最佳成分范围。     

GH99与ЭП693合金板材标准比较

ＧＨ９９与ЭП６９３合金板材标准比较北京航空材料研究所王炳林ＧＨ９９是我国冶金与航空工业部门大力协同自行研制的一种用于航空燃气涡轮发动机加力燃烧室简体的时效强化型镍基合金。该合金已成功地在多种现役发动机中使用，对于减轻发动机的重量具有很大意义。ＧＨ９...     

Inconel718合金扩散连接接头的组织与性能研究

对细晶Incone1718高温合金无中间层和加Ni箔中间层两种情况下的扩散连接进行了研究,分析了不同的连接温度、连接压力、连接时间等工艺参数对接头剪切强度的影响;通过SEM、EPMA和金相技术对接头微观组织和力学性能进行了分析.确定了获得优质接头的最佳工艺参数区间,即扩散连接温度T=1 050℃,连接压力P=20 MPa,连接时间t=45 min,选用Ni箔作为中间层,厚度为25 μm.     

新型高温合金718Plus的性能特点、航空应用和发展趋势

718Plus合金凭借其优异的力学性能、较高的耐温能力、良好的加工性和适宜的制造成本,有效填补了IN718和Waspaloy合金之间长期以来存在的合金空白,逐渐应用于高性能航空发动机零部件制造。详细阐述了新型高温合金718Plus的性能特点,包括化学成分、析出相、热处理制度和力学性能等。此外,还总结了718Plus合金的制造成本和航空应用情况。     

ATI 718 Plus高温合金微观组织与性能研究进展

ATI 718Plus(以下简称718Plus)是一种基于IN718高温合金改进的时效强化型镍基变形高温合金,已广泛应用于航空发动机的热端零部件.合金最初以锻造态引入,随着航空航天领域对大型复杂零部件需求的提高,锻造态合金已不能满足实际要求,因此在锻造态合金的基础上通过提高Nb含量开发出了铸造718Plus合金,并对其微观组织、焊接性能和拉伸性能开展了研究.锻造态和铸造态合金的化学成分与成型工艺的差异导致其微观组织及性能不同,因此阐明两种合金微观组织与使役性能之间的内在联系具有重要意义.本文综述了近年来锻造态和铸造态718Plus合金的微观组织调控及性能研究进展,包括:元素含量与分布状态对合金微观组织的影响,热处理制度对γ'相及η相分布状态的影响,热变形工艺与合金微观组织的关系,并得到最优热加工参数,总结了服役环境对合金蠕变、疲劳、焊接及抗氧化性能的作用机制,最后分析了合金研究过程中存在的问题及发展趋势.     

硼、硫和铝对磷在IN718合金中作用的影响

分析了硼、硫和铝对磷在ＩＮ７１８合金中作用的影响．结果表明,磷改善晶界δ相, 显著提高 持久性能．磷提高持久寿命的相对幅度不受铝含量的明显影响,但随着硼含量的增加而加强、硫含量的增 加而减弱．硼、硫和铝对磷的作用的影响取决于其各自的晶界行为．     

GH3044高温合金化学铣切工艺及其应用

试验了ＧＨ３０４４的化学铣切工艺，讨论了配方中各主要成分的作用，对影响化铣后材料性能的组织缺陷、晶间腐蚀倾向、力学性能进行了检查测试，介绍了本工艺在生产中的应用情况。     

氧化物弥散强化（ODS）合金在高温领域的应用

扼要阐述了铁、基二类氧化物弥散强化合金的发展状况、加工工艺、高温性能及其应用前景。     

IN718(GH169)合金中α-Cr析出相的研究进展

简要综述了国外对IN718合金中体心立方α-Cr相析出规律的研究成果,同时亦介绍了国内外对IN718（GH169）中α-Cr相析出行为的一些研究结果,提出了在IN718合金中与α－Cr析出相有关的,尚待解决的问题。     

高温合金GH4169管材挤压工艺及组织分析

对高温合金GH4169管材挤压成形进行了工艺研究.确定了GH1140管材挤压成形工艺参数,分析了GH4169管材挤压力能参数变化规律.分析了管材挤压对组织性能的影响.研究结果发现,GH4169管材挤压成形时必须严格控制坯料温度、模具预热温度、润滑方式、挤压速度、挤压比等工艺参数.     

非平衡晶界偏聚理论在INCONEL 718合金研究中的应用

评述了国际上将溶质晶界偏聚领域的最新研究成果－非平衡晶界偏聚理论，用于INCONEL718合金研究中所取得的最新进展。     

Continuous cooling transformation behavior of Alloy 718

The transformation behavior of Alloy 718 is affected significantly by the cooling rate. The γ″-phase appears at cooling rates less than 20 °C/min and δ-phase appears at grain boundaries as well as the MC type carbides at cooling rates below 5 °C/min. The δ-phase nucleates and grows preferentially at grain boundaries, and less preferentially at the MC carbides. The size of the γ″ and δ-precipitates increases consistently with decreasing cooling rate for the given conditions. The hardness varies with the transformation behavior. A hardness peak was noticed for a cooling rate of 5 °C/min. The hardness peak corresponded to the maximum volume fraction of γ″ which in turn was strongly affected by the presence of the δ-phase.     

低磷GH169和常规GH169合金力学性能的对比研究

对国内生产的低磷GH169[s（P）＜0．001％]及常规GH169[w（P）0.008％～0．013％]变形合金锻件的力学性能进行了对比研究。结果表明，室温拉伸和高温拉伸强度未显现很大差异，然而低磷GH169合金反而显示出高温塑性特别是650℃／686MPa持久塑性的明显降低，且低磷合金在蠕变和疲劳／蠕变交互作用下的裂纹扩展速率皆高于常规合金，低磷合金的595℃／895MPa缺口周期持久寿命亦有降低的趋势。俄歇能谱分析表明，磷在晶界发生偏聚，透射电镜观察，发现低磷合金中的σ相的片状形式沿晶界析出，而磷含量提高使σ相的胞状形式沿晶界析出。     

Multisheet structure of Inconel 718 superalloy processed by LBW/SPF technology and its microstructure

Abstract

Multisheet structure of Inconel 718 superalloy will be widely used in vehicles as heat resisting and heat shielding structure due to its lightweight, high strength and stiffness. Multisheet structure of Inconel 718 superalloy was processed by laser beam welding and superplastic forming (LBW/SPF) technology in the present paper. Multisheet structure of Inconel718 superalloy processed by LBW/SPF technology exhibits good configuration and uniform thickness distribution. Laser beam welding parameters for multisheet structure were as follows: pulse frequency was 32 Hz; pulse duration 3 ms; peak power per pulse 4500 W; welding speed 180 mm min^–1; SPF parameters were as follows: temperature T_f=965°C; forming pressure P _f=4·2 MPa; forming time t _f=130 min. Microstructure of multisheet structure was studied carefully. Microstructure in weld fusion zone was constituted of austenite dendritics and Laves phase precipitated in interdendritics. After SPF process, austenite dendritics in the weld fusion became coarser and most of Laves phases were dissolved and turned into δ precipitated phase but a few of Laves phases were still reserved. And Nb concentration in dendritics increased to 5·42% compared to 2·82% under as welded condition. Weld metal hardness increased from 331·63 under as welded condition to 391·74 under post-SPF condition which was closed to the base material hardness of post-SPF. Grain size of base material grew slightly and an amount of precipitated phase appeared in the base material undergoing SPF process. The tensile test results of base material show that tensile strength increased obviously and the ductility decreased slightly after SPF process. Therefore, LBW/SPF technology is an appropriate forming technique for multisheet structure of Inconel 718 superalloy.     

Microstructure and mechanical properties of Inconel 718 electron beam welds

Abstract

Bead on plate, full penetration electron beam welds were produced in 2 mm thickness sheets of Inconel 718 in the solution treated condition. Welds were subjected to an aging treatment with and without post-weld solution treatment. Weld microstructures, high temperature tensile properties and stress rupture properties were evaluated. The as welded fusion zone showed a considerable amount of interdendritic niobium segregation and brittle intermetallic Laves phase. The tensile and stress rupture properties of the welds after post-weld aging treatment were found to be inferior in relation to the base metal. Post-weld solution treatment at 980°C was found to result in partial dissolution of Laves phase, some reduction in niobium segregation and the formation of δ phase needles around the Laves particles. The use of 980°C solution treatment was found to improve the weld properties to some extent, although not to the level of the base metal. The reasons for this behaviour are discussed, correlating microstructures, fracture features and mechanical properties.     

温度对718镍基合金在高酸性环境下耐腐蚀性能的影响

718镍基合金是高酸性油气井中常用的金属材料,但目前对其腐蚀机理和影响因素的研究较少。利用高温高压反应釜进行腐蚀模拟,采用失重法、扫描电镜(SEM)等手段研究了温度对718镍基合金在高含H_2S/CO_2环境下腐蚀行为的影响。结果表明:在CO_2分压3.5 MPa、H_2S分压3.5 MPa、Cl~-含量150 000 mg/L的模拟环境下,718镍基合金在150,175,205℃下均呈现全面腐蚀,未出现点蚀和局部腐蚀。但随温度升高,镍基合金718的均匀腐蚀速率逐渐增加,材料表面钝化膜出现硫化,并逐渐向腐蚀产物膜转变,质地由致密变得疏松。     

Electron beam melting of Inconel 718: effects of processing and post-processing

ABSTRACT

This study reports the effect of process temperature on microstructure evolution of electron beam melted Inconel 718. Samples fabricated at 915°C had fine grain boundary δ (～200?nm) along with coarse intragranular δ spanning through the length of the grains. On the other hand, samples fabricated at 990°C, only had grain boundary δ along with secondary carbides. During hot isostatic pressing, the distribution of carbides governs the grain growth vs. lack of it. The samples fabricated at 990°C having grain boundary carbides had no grain growth owing to the pinning effect of carbides. In contrast, the sample processed at 915°C had significant grain growth owing to dissolution of grain boundary δ phase and absence of grain boundary carbides.     

真空热处理对激光近净成形In625和C-276合金性能的影响EI北大核心CSCD

对激光近净成形两种镍基高温合金Inconel 625和Hastelloy C-276分别进行热处理实验,然后分析热处理工艺参数对合金室温拉伸性能的影响。结果分析表明:在800,900℃去应力热处理后,Inconel 625合金抗拉强度提升不明显,而在1000℃以上进行固溶处理后,合金抗拉强度得到提高。1100℃热处理后,Inconel 625合金的抗拉强度与沉积态相比得到明显提高。在800,900℃去应力热处理后,Hastelloy C-276合金强度也未明显提高,而在1000℃以上进行热处理,随着热处理温度提高,合金抗拉强度逐渐升高。1150℃进行热处理后,Hastelloy C-276合金的抗拉强度与沉积态相比得到明显提高。激光近净成形工艺制备的两种镍基高温合金室温拉伸断裂方式为韧性断裂。     

Processing and Microstructural Evolution of Superalloy Inconel 718 during Hot Tube Extrusion

The processing parameters of tube extrusion for superalloy Inconel 718 (IN 718), such as slug temperature, tools temperature, choice of lubricant, extrusion ratio and extrusion speed, were determined by experiment in this paper. An appropriate temperature range recommended for the slug is 1080～1120℃, and the temperature range recommended for the tools is 350～500℃. The microstructural evolution of superalloy IN 718 during tube extrusion was analyzed.With the increase of the deformation the cross crystal grains were slightly refined. While the vertical crystal grain is elongated evidently and the tensile strength increased along the axial rake. Glass lubricants have to be spread on the slug surface after being heated to 150～200℃, vegetable oil or animal oil can be used as the lubricant on the surface of the tools to reduce the extrusion force remarkably.