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EFFECT OF ZIGZAG GRAIN BOUNDARY ON CREEP RUPTURE OF A 10Cr-15Co-Ni-BASE WROUGHT SUPERALLOY

金属学报 , 1984,
Abstract: Investigation was made of the effect of the zigzag or straight grain boundary, which may be obtained by two different schemes of heat treatment, on the creep rupture of a 10Cr-15Co-Ni-base wrought superalloy, especially, on the reason whyits strength and plasticity at elevated temperature can be improved by the zigzaggrain boundary. It is shown that the zigzag grain boundary may delay the initiation, growth and propagation of crack, as well as may also influence the crack morphology and the fracture mode markedly. Furthermore, the zigzag grain boundary may intensively inhibit the grain boundary sliding and retard the crack joining, thus, force the bulk-grains to take part in more deformation. It displays an important role in the tertiary stage of creep. The creep life to failure of the alloy tested with zigzag grain boundary was increased by a factor of 1/4, and the plasticity was also improved slightly.
A STUDY OF ZIGZAG GRAIN BOUNDARY IN HIGH ALLOYED WROUGHT NICKEL-BASE SUPERALLOY

by ZHONG Zengyong,MA Peili,CHEN Gansheng,

金属学报 , 1983,
Abstract:
EFFECT OF SILICON ON THE TRANSITION OF BRITTLENESS IN A NICKEL BASE WROUGHT SUPERALLOY

Wang Yunshi,Bi Jing,Guan Xuemin,Zhang Xizhang,Wang Jingyun,Lin Shuzhi,Xu Anshuang,

金属学报 , 1979,
Abstract: The tensile strength, ductility or impact value of a wrought nickel base super-alloy Ni-15Cr-6W-3Mo-2Al-2Ti depend markedly upon the silicon content of thealloy. On plotting these mechanical properties vs the silicon content which rangesfrom 0.1 to 0.89%, a saddle shown by the existence of a minimum at about 0.4-0.6% Si occurs. There is reason to believe that such a saddle behavior may be caus-ed by the variation of mechanical properties with the type, amount and morpho-logy of carbides as well as with the sequence of carbide precipitation in the alloyas influenced by its silicon content. Thus, the amount of M_6C and M_(23)C_6 precipi-tated along the grain boundaries would appear to proceed in four stages as follows: 1. For silicon content up to 0.1%, globular M_(23)C_6 may be the sole type ofcarbide formed; 2. In the range from 0.1 to 0.4% Si, besides M_(23)C_6, M_6C begins to appearand increases with increase of silicon content. The morphology of the carbidesseems to be different, however, being in a discontinuous, blocky form; 3. In the range from 0.4 to 0.6% Si, continuous films of M_6C were present.As might be expected, this type of carbide is very detrimental to the tensile andimpact properties at room temperature. The precipitation of M_(23)C_6 was slowed downor even suppressed; 4. In the range from 0.6 to 0.89% Si, M_6C may be altered to discontinuous,blocky form, whereas M_(23)C_6 may be very much limited. In conclusion, the detrimental effect of carbide is mainly associated with itsfilm-like morphology especially along the grain boundaries. Of course, carbides ingranular form are good strengtheners. According to prevailing view, criterion for the formation of either M_6C orM_(23)C_6 in nickel base superalloys would seem to be the relative Mo and W con-tents, e. g. if Mo+1/2W>6%, M_6C will be formed. Present work indicates that si-licon plays as equally important role in the formation of M_6C besides the Mo andW contents of the wrought nickel base superalloys.
GRAIN BOUNDARY EMBRITTLEMENT BY μ AND σ PHASES IN IRON-BASE SUPERALLOYS
陈国良,谢锡善,倪克铨,徐志超,王迪,张明,居玉英
金属学报 , 1981,
Abstract: 本文研究了15Cr-25Ni和15Cr-40Ni型铁基高温合金中μ和σ相引起的晶界脆化。在铁基高温合金中当晶界存在少量的μ和σ相时(甚至其含量在0.01—1%间),就会引起合金脆化,其脆化程度与晶界存在的μ和σ相的密集系数成正比关系。冲击试验时的脆化导致沿晶断裂,μ和σ相所引起的断裂机构是完全不同的。减小晶粒尺寸或控制合金化学成分使晶界上的μ和σ相减少或根本不生成,则可以控制或消除合金的脆化效应。
Self-consistent Constitutive Modeling of the Creep Damage Behaviour of Nickel-base Directionally Solidified Superalloys with Different Grain Orientations
Zhufeng YUE,Zhenzhou LU,

材料科学技术学报 , 1998,
Abstract: A self consistent creep damage constitutive model is developed for nickel-base directionally solidified superalloys. Grain degradation and grain boundary voiding are considered. The model parameters are determined from the creep test data of single crystal and directionally solidified superalloy with a special grain orientation. The numerical analysis shows that the model creep damage behaviours of nickel-base directionally solidified superalloys with difFerent grain orientations are in good agreement with the experimental data.
CREEP BEHAVIORS OF Mg MICROALLOYED WROUGHT SUPERALLOYS
MA Peili YUAN Ying ZHONG Zengyong Central Iron,Steel Research Institute,Ministry of Metallurgical Industry,Beijing,China MA Peili Senior Engineer,Labof Superalloy,Central Iron,Steel Research Institute,Ministry of Metallurgical Industry,Beijing,China,
MA Peili YUAN Ying ZHONG Zengyong Central Iron and Steel Research Institute
,Ministry of Metallurgical Industry,Beijing,China MA Peili Senior Engineer,Lab.of Superalloy,Central Iron and Steel Research Institute,Ministry of Metallurgical Industry,Beijing,China

金属学报(英文版) , 1990,
Abstract: By adding small amount of Mg to the wrought superalloys,the steady stage of creep,and es- pecially the tertiary stage of creep are prolonged.Also,the steady creep rate is decreased within the range of low strain rates.At higher strain rates,however,the effect of Mg on creep rate vanishes.This may be attributed to the Mg dissolution in the matrix.A mechanism of the effects of Mg addition on creep behaviors is proposed.
SPRAY FORMED NICKEL-BASE SUPERALLOYS
Z Li,SF Tian,XG Zhao,ZK Liang,LP Ren,GFMi,MG Yan,
Z. Li
,S.F. Tian,X.G. Zhao,Z.K. Liang,L.P. Ren,G.F.Mi and M.G. Yan

金属学报(英文版) , 1996,
Abstract: In this paper,part of the research and development work in the field of spray formed superalloys at BIAM of China is briefly summarized. With an experimental spray forming facility,whose melting capacity is suitable for making disk and columnar shaped integral-dense and clean Ni-base superalloy preforms with low oxygen content,fine grain, uniform chemistry and improved forgeability, a series of Ni-base superalloys have been spray atomized and deposited, among which three alloys have been chosen for microstructural and mechanical properties evaluation.
PROPERTIES, WELDABILITY AND APPLICATIONS OF ADVANCED WROUGHT SUPERALLOYS FOR GAS TURBINE ENGINES
DLKlarstrom,VRIshwar,MDRowe,
D.L.Klarstrom
,V.R.Ishwar,M.D.Rowe

金属学报(英文版) , 2005,
Abstract: Alloy selection and alloy design both require consideration of an array of material attributes, including in-service properties, weldability and fabricability. Critical properties of advanced wrought superalloys for gas turbine applications include high temperature strength, thermal stability, oxidation resistance and fatigue resistance. In this paper, the properties of twelve wrought solid-solution-strengthened and six age-hardenable superalloys are compared. Weldability is an important attribute and can be a major limiting factor in the use of certain alloys. Weldability test methods are discussed and the resistance of alloys to solidification cracking and strain-age cracking is compared. The use of weldability testing in the development of modern wrought su-peralloys is discussed with several examples cited. Finally, alloy selection for gas turbine components is outlined, taking into account both alloy properties and fabricability.
NEW DEVELOPMENTS IN WROUGHT 718-TYPE SUPERALLOYS
WDCao,RLKennedy,
W.D.Cao
,R.L.Kennedy

金属学报(英文版) , 2005,
Abstract: Research and development efforts are still very active on 718-type alloys although two major members of this widely used family, 718 and 625, were invented almost a half-century ago. Emphasis in this type of work at ATI Allvac is directed at improving existing alloys and developing new alloys to meet ever-increasing industrial demands. The improvement of existing alloys is exemplified by addition of minor elements P and B in alloy 718. The discovery of the beneficial effect of P and B in wrought alloy 718 led to development of a new, modified alloy, AllvacH 718 ERR. A large effort has also been directed at studying the effects of major element modifications in 718-type alloys, and a new alloy, AllvacR 718PlusTM, has been developed. The new alloy has much better high temperature capability, especially thermal stability, approaching the level of Waspaloy but retains excellent processing characteristics, similar to alloy 718. Alloy 718PlusTM should be useful in any 718-type application requiring a higher working temperature. The properties and processing of this alloy are introduced in this paper.
EFFECT OF Mg CONTENT ON CREEP BEHAVIOUR OF Ni-BASE WROUGHT SUPERALLOY

KE Da'nian,ZHONG Zengyong,

金属学报 , 1983,
Abstract: The effect of addition of Mg on the creep behaviour of Ni-base wrought superalloy has been investigated. It was found that the trace Mg added may cause the alteration of continueous lath carbide into discontinueous massive one at the grain boundaries. It may also promote the spheroidization of the grain boundary carbide, decrease the diffusion coefficient of grain boundary and increase the activation energy for creep. The grain boundary energy and the boundary energy between grain boundary carbide and matrix are decreased and bonding strength of interface increased. Thus, the creep property and the creep-rupture life as well as the stress exponent of creep of the superalloy may be significantly improved by the impediment of the boundary sliding and the prevention of the nucleation and propagation of cracks.
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