宁礼奎郑志谭毅刘恩泽佟健于永泗王华
金属学报
研究了新型定向凝固镍基高温合金DZ68的抗热腐蚀性能, 并与K438合金进行了比较. 结果表明: 热处理态DZ68合金组织中几乎没有(γ+γ') 共晶, 碳化物尺寸小,其整体组织比较均匀; 在热腐蚀过程中发生比较均匀的腐蚀, 其外腐蚀层的腐蚀产物主要是(Ni, Co)Cr2O4, 内腐蚀层的腐蚀产物主要是Al2O3. 热处理态K438合金组织中存在较多的 (γ+γ'共晶和数量较多、尺寸较大的长条状碳化物, 组织均 匀性较差; 在热腐蚀过程中发生不均匀腐蚀, 其外腐蚀层的腐蚀产物主要是NiO, 内腐蚀层的腐蚀产物主要是CrS.两种合金中Ti元素的偏析有促进其它元素偏析的倾向, 使合金组织的均匀性恶化,热腐蚀均匀性变差. 在本实验条件下, DZ68合金的抗热腐蚀性能略好于K438合金.
关键词:
DZ68
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hot corrosion
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superalloy
鲁金涛
,
谷月峰
,
杨珍
腐蚀学报（英文）
研究了3种700℃超超临界燃煤锅炉备选高温合金Inconel 740,CCA617,GH 2984在760℃现役机组煤灰腐蚀介质中的高温腐蚀行为.结果表明:镍基合金Inconel 740和CCA 617均能形成保护性的Cr2O3氧化膜,局部点蚀为其主要失效形式.点蚀区域氧化膜为多层结构,由外到内依次为Ni(Co)O、Cr2O3(TiO、Al2O3)以及少量内层硫化物:较高Cr、Al含量提高了Inconel 740合金的耐蚀性能;挥发性产物与氧化膜微区溶解降低了CCA 617合金氧化膜的致密性.GH 2984合金因含有较多的Fe未能形成保护性的氧化膜,氧化膜分层生长,且出现了严重的剥落现象.
关键词:
700℃超超临界
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高温合金
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煤灰腐蚀
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腐蚀机理
M.F. Geng(Luoyang Ship Material Research Institute
,
Luoyang 471039
,
China)
金属学报(英文版)
The crack growth behavior and fracture feature of superalloy GH2132 (equivalent to A286) under creep-fatigue conditions have been studied in the present paper. The tests were carried out at 550℃ under various cyclic freqencies (hold time) and load levels,and the fracture surfaces were examined by using a scanning electron microscope. It is shown that the fracture mode of creep-fatigue and the effect of cyclic loading on crack growth change with the growth of crack and the increase of net-section stress,and both are reversed when the net-section stress is up to the yield stress of material.When σn <σ0.2, cracking is predominantly cycle-dependent transgranular and cyclic loading accelerates creep crack growth, whereas when σm>σ0.2, the case is reversed.
关键词:
creep-fatigue
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null
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null
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null
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null
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null
J.F. Sun
,
J. Shen
,
Z. Y. Li
,
J. Jia and Q.C. Li National Key Laboratory of Metal Precision Hot Processing
,
Harbin Institute of Technology
,
Harbin 150001
,
China
金属学报(英文版)
Based on the Newtonian heat transfer formulation and classical heterogeneous nucleation theory, a mathematical model has been established to predict the profile of flight velocity, heat transfer coefficient, temperature, solid fraction and cooling rate of atomizing droplets for a superalloy. The results indicated that above parameters change with different droplet size and flight distance. The changing trend as well as the mechanism for the change are described and discussed.
关键词:
spray forming
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null
,
null
,
null
Z. Li
,
S.F. Tian
,
X.G. Zhao
,
Z.K. Liang
,
L.P. Ren
,
G.F.Mi and M.G. Yan(Bejing Institute of Aeronautical Materials
,
Beijing 100095
,
China Manuscript received 26 August 1996)
金属学报(英文版)
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.
关键词:
:spray forming
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null
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null
