检索结果-南通市图书馆

Journal of university of science and technology beijing 2002年第4期9卷 282-286页

作者： maicang zhang, jianxin dong,{2., xishan xiematerials science and engineering School, university of science and technology beijing, beijing 100083, china Mat. Sci. and Eng. Sch. Univ. of Sci. and Technol. Beijing Beijing 100083 China

The flow behavior of Rene 95 PM alloy was studied from 1050 to 1150 deg Cwith strain rate of 1 X 10^(-3), 1 X 10^(-2., 1 X 10^(-1) and 1 s^(-1). At a given temperature andstrain rate, flow curves exhibit a peak followed by flow softening up to a steady state. Moreover,at constant strain, flow stress increases with increasing strain rate and decreasing temperature. Anequation relating hyperbolic sine of flow stress to hot working parameters, such as strain, strainrate and temperature, was established by using multiple nonlinear regression method. A very goodagreement was found between predicted and experimental flow stress in all the strain rangeinvestigated. Application of the constitutive equation in predicting forming loads and flow behaviorand temperature distribution in both upper and lower dies in an isothermal forging process ofturbine disk of large dimension (about 630 mm) by means of a finite element code was systematicallyanalyzed.

关键词： constitutive equation finite element method isothermal forging Rene 95PM alloy

SEM In-situ Observation at Tensile Loading on Surface Inclusion in PM Rene95 Superalloy

在线全文

学校读者我要写书评

暂无评论

Journal of university of science and technology beijing 2001年第4期8卷 286-289页

作者： Xiao Li, Lina zhang, jianxin dong, {2., Yaohe Hu, xishan Xie Materials science and engineering School. university of science and technology beijing. beijing 100083. china Materials science and engineering School University of Science and Technology Beijing Beijing 100083 China

The observation on crack initiation and propagation of surface inclusion Al2.3 in seeded PM Rene95 was conducted by SEM in-situ tension test. The results show that the cracks often initiate at the inclusion/matrix interface vertical to the applied stress direction, and easily propagate along the interface into the matrix. The interface of inclusion/matrix is just mechanically bounded on the base of SEM observation. The weak bonding of inclusion/matrix interface and stress concentration around inclusions are the main reasons of the matrix/inclusion interface debonding and local plastic deformation under the tensile loading in the in-situ tension test. Surface inclusion does not definitely lead to the failure of in-situ tension test. But the early surface crack initiation caused by ceramic inclusion is critically harmful to the LCF property of PM Rene95 superalloy, which can't be ignored.

关键词： inclusions SEM in-situ observation PM Rene95 stress concentration

Superplastic deformation of commercial OOCr2.Ni5Mo3N0.17 duplex stainless steel

在线全文

学校读者我要写书评

暂无评论

Journal of university of science and technology beijing 2003年第2期10卷 49-55页

作者： Peixue zhang, Xueping Ren, and jianxin {2. science and engineering School, university of science and technology beijing, beijing 100083, china

The superplastic behavior of a commercial duplex stainless steel has beenstudied by means of isothermal hot tensile test at temperatures of 850-1050 deg C for the initialstrain rates ranging from 3X10^(-4) s^(-1) to 5X10^(-2. s^(-1). At 960 deg C, the best superplasticdeformation that caused the maximum elongation greater than 840 percent was obtained for an initialstrain rate of 1.2.10^(-3) s^(-1). At 850 deg C, the best elongation 500 percent was achieved for aninitial strain rate of 2.5X10^(-3) s^(-1) During the deformation in higher temperature region,coarse gamma grains formed during the prior treatments were broken into spherical particles,resulting in a homogeneous dispersion of gamma particles within the delta-ferrite matrix. However,at lower temperatures between 800 and 950 deg C, the sigma phase was formed through the eutectoiddecomposition of delta->gamma+sigma, resulting finally in the stable equiaxed micro-duplexstructures with delta/gamma and gamma/sigma respectively. The precipitation of the sigma phaseplayed an important role in improving the superplasticity at 850 deg C. The strain-rate sensitivitycoefficient, m-values, were also determined by the strain rate change tests. The microstructurestudies show that the superplastic process occurs mainly by the local work hardening and thesubsequent dynamic recrystallization and a grain boundary sliding and grain switching mechanism.

关键词： duplex stainless steel superplasticity strain-rate sensitivitycoefficient isothermal hot tensile test

Crack initiation and propagation induced by inclusions in a nickel-base P/M superalloy under fatigue load

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2005年第3期24卷 298-300页

作者： zeng yanping {2. maicang dong jianxin {2. Lina XIE xishan High Temperature Materials Research Laboratory University of Science and Technology Beijing Beijing 100083 China School of Materials science and engineering Tsinghua University Beijing 100084 China

In situ fatigue tests in special designed SEM were conducted to trace the whole process of crack initiation and propagation fill to fracture in mckel-base P/M superalloy seeded inclusions. The experimental results show that non-metallic inclusions can induce crack initiation. When the inclusion size is larger than the critical one, the crack can propagate as the main crack that induces the specimen to fracture. As a result, the LCF life of the specimen decreases.

关键词： nickel-base P/M superalloy inclusion crack initiation and propagation fracture

两种高铬Ni-Cr基高温合金的组织与性能的比较

在线全文

学校读者我要写书评

暂无评论

中国稀土学报 2005年第S2期23卷 152-157页

作者：韩莹董建新曾燕屏张麦仓北京科技大学材料科学与工程学院北京100083

为研究和改进高铬Ni-Cr基高温合金的组织与性能,本文从力学性能、断口形貌、微观组织几个方面对设计合金和GH648合金两种高铬Ni-Cr基高温合金进行了分析比较,结果表明,设计合金的强度尚可,塑性较差,主要原因在于设计合金中的-αCr相组... 详细信息

为研究和改进高铬Ni-Cr基高温合金的组织与性能,本文从力学性能、断口形貌、微观组织几个方面对设计合金和GH648合金两种高铬Ni-Cr基高温合金进行了分析比较,结果表明,设计合金的强度尚可,塑性较差,主要原因在于设计合金中的-αCr相组织特征是晶界处以不规则块状析出,在晶内则呈交织成网的针状.要改善设计合金的塑性,需要得到类似GH648合金中-αCr相呈球状或短棒状组织均匀而弥散分布的组织,若要进一步改善合金的高温性能,还需要采取多元合金元素固溶强化的途径。

关键词：高铬Ni-Cr基高温合金微观组织力学性能断口

Phase transformation and liquid density redistribution during solidification of Ni-based superalloy Inconel 718

在线全文

学校读者我要写书评

暂无评论

china Foundry 2012年第3期9卷 263-268页

作者： Wang Ling Gong He Zhao Haofeng dong jianxin {2. maicang School of Physics and Optoelectronic engineering Nanjing University of Information Science and TechnologyNanjing 210044China School of Materials science and engineering University of Science and Technology of BeijingBeijing 100083China

The influences of chemical segregation and phase transformation on liquid density variation during solidification of Ni-based supperalloy Inconel 718 were investigated using SEM and EDS. It was found that significant segregation in liquid prompts high Nb phase to precipitate directly from liquid, which results in the redistribution of alloy elements and liquid density in their vicinity. The term "inter-precipitate liquid density" is therefore proposed and this concept should be applied to determine the solidification behavior of superalloy Inconel 718.

关键词： Inconel 718 Nb segregation phase transformation inter-precipitate density inversion

在线全文

学校读者我要写书评

暂无评论

GH4738高温合金的应力松弛影响因素

稀有金属材料与工程 2017年第9期46卷 2546-2552页

作者：朱擎董建新张麦仓姚志浩北京科技大学北京100083

详细研究了紧固件用高温合金GH4738在不同温度和初应力,及不同热处理制度下的应力松弛行为。研究表明:应力松弛的两个阶段之间存在一个槛应力σ'_0,低于此槛应力σ'_0时,塑性应变速率快速下降。随着温度的升高,GH4738合金的松弛稳定性下... 详细信息

详细研究了紧固件用高温合金GH4738在不同温度和初应力,及不同热处理制度下的应力松弛行为。研究表明:应力松弛的两个阶段之间存在一个槛应力σ'_0,低于此槛应力σ'_0时,塑性应变速率快速下降。随着温度的升高,GH4738合金的松弛稳定性下降,应力松弛速率加快,松弛极限降低。随着初应力的提高,松弛第1阶段松弛速率加快,松弛极限有所增大。不同的固溶温度和稳定化热处理工艺主要影响了合金松弛过程的第2.段,对其槛应力及松弛稳定性均无明显影响。

关键词： GH4738 应力松弛温度初应力热处理制度

在线全文

学校读者我要写书评

暂无评论

服役条件下镍基高温合金应力松弛微观机制

金属学报 2019年第9期55卷 1211-1220页

作者：江河董建新张麦仓姚志浩杨静北京科技大学材料科学与工程学院

以4种典型镍基高温合金(GH4169、GH4169D、GH4738、GH350)为研究对象,在600~780℃和2.0~510MPa范围内对其进行应力松弛实验,并利用FESEM和TEM对应力松弛后的样品进行组织观察分析,系统研究了典型镍基高温合金服役条件下应力松弛的微观... 详细信息

以4种典型镍基高温合金(GH4169、GH4169D、GH4738、GH350)为研究对象,在600~780℃和2.0~510MPa范围内对其进行应力松弛实验,并利用FESEM和TEM对应力松弛后的样品进行组织观察分析,系统研究了典型镍基高温合金服役条件下应力松弛的微观机制。结果表明,在应力松弛实验过程中应力在开始阶段快速下降后趋于稳定;合金的松弛稳定性随着温度的升高而降低。应力松弛实验中试样的形貌不发生明显改变,而TEM分析表明应力松弛的主要微观机制是位错的运动和析出相对位错运动的阻碍。合金中析出相的种类、尺寸、形态和分布影响了析出相对位错运动阻碍作用的大小,从而决定了合金的应力松弛性能。

关键词：高温合金应力松弛组织演变机制

镍基耐蚀92.合金均匀化及固溶过程组织演变规律

在线全文

学校读者我要写书评

暂无评论

稀有金属材料与工程 2018年第7期47卷 2080-2086页

作者：李景阳董建新姚志浩张麦仓北京科技大学北京100083

为研究92.合金在均匀化及固溶过程中组织演变规律,利用金相显微镜、扫描电镜和能谱分析等对经真空感应熔炼(VIM)和保护气氛下电渣重熔(ESR)双联工艺冶炼的92.合金的原始铸态、均匀化态、锻态和固溶态的组织和析出相进行分析。结果表明:... 详细信息

为研究92.合金在均匀化及固溶过程中组织演变规律,利用金相显微镜、扫描电镜和能谱分析等对经真空感应熔炼(VIM)和保护气氛下电渣重熔(ESR)双联工艺冶炼的92.合金的原始铸态、均匀化态、锻态和固溶态的组织和析出相进行分析。结果表明:铸态组织中含有TiN、MC、γ'相、σ相以及η相;1160℃退火5 h可使γ'相、σ相及η相回溶,退火2. h偏析基本消除;在950～1070℃固溶过程中,主要析出相M_(2.)C_6在晶界析出量逐渐减少,高于1040℃时晶粒急剧长大。

关键词：高温合金 92.合金固溶均匀化

800℃以上服役涡轮盘用难变形镍基高温合金研究进展

在线全文

学校读者我要写书评

暂无评论

航空制造技术 2021年第1期64卷 62-73页

作者：江河董建新张麦仓姚志浩北京科技大学材料科学与工程学院北京100083

大推重比航空发动机涡轮盘需在更高温度下服役,为满足更高温度服役航空发动机涡轮盘材料的需求,在新合金的发展过程中合金化程度和γ′相含量逐渐提高。其中GH4151、GH4175和GH4975合金是800℃以上服役变形高温合金的典型代表。对难变... 详细信息

大推重比航空发动机涡轮盘需在更高温度下服役,为满足更高温度服役航空发动机涡轮盘材料的需求,在新合金的发展过程中合金化程度和γ′相含量逐渐提高。其中GH4151、GH4175和GH4975合金是800℃以上服役变形高温合金的典型代表。对难变形高温合金国内外的发展趋势、3种典型合金的特征和发展过程进行了概述,并对难变形高温合金制备过程中开坯工艺和超塑性等问题进行了探讨。为充分发挥800℃以上服役高相含量难变形高温合金的优势和作用,需对合金成分设计特点、组织特性、热变形和超塑性变形过程中相的作用机制等方面开展相应的理论研究工作。

关键词：变形高温合金难变形开坯工艺超塑性高γ′相含量