航空材料学报

CARBIDE STRENGTHENING IN CAST SUPERALLOYS ON NICKEL BASE

S. T. Kishkin, G. B. Stroganov

1991, 11(2): 1-8.

[Abstract](1353) [PDF 688KB](196)

Abstract:
In this article mechanism of formation and role of three types of carbides— MC,M23C6 and M6C are described in combination with Sovit Union’s theory and practiee in east superalloys on nickel base.Transformation of carbides under different conditions is discussed.It is pointed out that"Chinese character"MC carbide can be formed from Iiquid and M6C carbide—from melt during crystallization.In author’s view emphasis must be placed on the study of influence of Hf on carbide formation and change of survice properties restricted by carbide reaction.

A STUDY OF DIRECTIONAL SOLIDIFICATION PROCESS OF TURBINE BLADES AND ITS APPLICATION ASPECTS

R. E. Shalin, E. N. Kablov, V. V. Gerassimov

1991, 11(2): 9-15.

[Abstract](1402) [PDF 1346KB](177)

Abstract:
A new process of cast turbine blades and its application in batch production are described.Besides the special device for this purpose and new superalloys are also introduced.A schematic drawing of the new process is shown,the key point of which is adopting the crystallizer of liquid metal,double-region resistance heater and specially manufactured ceramic mould and core in accordance with technological demand. The use of metal coolant results in obvious enhancement of heat radiation speed of casting,improvement of structure of alloy and dispersity of all compositions,and good effect on property of alloy. The trail run of new process and device in production condition is also described,and percents of qualitified blades produced by factories in the first five years are sumerized.

VACUUM PLASMA HIGH—ENERGY PROCESS FOR DEPOSITION OF MULTICOMPONENT PROTECTIVE COATINGS

S. A. Muboyadgyan, E. N. Kablov

1991, 11(2): 16-25.

[Abstract](1353) [PDF 1151KB](141)

Abstract:
Fundamentals of vacuum plasma high-energy technological process as applied to deposition ofmultieomponent protective coatings are considered.Results are presented on structure investigation for coatings deposited from two-phase flows of multicomponent plasma,containing coating material microdroplets;basic advantages and drawbacks of vacuum plasma coating deposition method are also discussed.

EXAMINATION AND ANALYSIS ON TURBINEBLADE OF DIRECTIONALLY SOLIDIFIED SUPERALLOY AFTER OPERATING

Zhang Jinghua, Tang Yajun, Yu Yang, Zhang Jishan, Hu Zhuangqi, Liao Huaqing

1991, 11(2): 26-32.

[Abstract](1344) [PDF 1715KB](262)

Abstract:
This paper presents an examination and analysis of Ⅱ stage turbine-blade of directionally solidified alloy after operating 150 hours.It has been found that there are no damages and cracks,the coating layer is also perfect at macro-scale. Examinations at micro-scale show that there is no change with grain boundries and γ′-precipitates.However,eutectic has been found to dissoluted partly and carbides M23C6 have been observed surrounding the MC.Oxidation and corrosion have been found to occur on the coating.The value in hardness is almost the same before and after operating

HIGH—TEMPERATURE BEHAVIOR OF INTERFACE BETWEEN SiC REINFORCING FIBRE WITH W CORE AND Si₃N₄ CERAMIC MATRIX

Zhao Jiapei, Zhao Saizhen, Li Fengmei

1991, 11(2): 33-43.

[Abstract](1336) [PDF 2754KB](161)

Abstract:
This paper deals with high-temperature behavior of interfaces between W and SiC,as well as SiC and Si3N4 in W core SiC fibre reinforced Si3N4 ceramic composite.At high-temperature region,the interdiffusion in compositions was studied,only few W diffused across SiC fibre could be discovered.Both interfaces kept clean and no evidence of fibre was broken during pressing and sintering process.The effect of adding SiC fibre on properties of ceramic composite is reducing flexural strength in both ambient and elevated temperature;obviously increasing fracture toughness of composite;slightly decreasing thermal shock resistance.It was probably because of internal strength which results from the difference of thermal expansion coefficients between W core SiC fibre and Si3N4.

PRECISION CASTING OF HIGH-STRENGTH ALUMINIUM ALLOY IMPELLERS

Liu Guoli, Zhang Jiakun, Mi Jiawei, Yao Weibin

1991, 11(2): 44-48.

[Abstract](1379) [PDF 1123KB](388)

Abstract:
A plaster mould casting technique manufacturing high-strength aluminium alloy impellers by home-made raw materials is introduced in this paper.This technique can be used for manufacturing impellers that have good surface finish, good metallurgical quality and high mechanical properties.Commercial uses in large quantity of this technique can obtain great techanical and economic profits.

THE EFFECT OF THE PRESSURE CHARACTERISTICS AT THE POUR-TUBE ORIFICE ON THE SIZE OF METAL POWDER IN USGA

Zhou Xingkun, Yu Guifu

1991, 11(2): 49-52.

[Abstract](1363) [PDF 328KB](204)

Abstract:
At the beginning of the investigation,introduction to the technique of USGA (Ultrasonic Gas Atomization)is simply performed.This study deals with the relation between the pressure characteristics at the pour-tube orifice and the size of metal powder in USGA.The conclusion shows that the size of metal powder is determined by the correlation between the jet gas pressure and the aspiration pressure at the pour-tube orifice.At last,the main elements which affect the size of metal powder are briefly described.

THE INFLUENCE OF AGEING CONDITION ON THE FRACTURE BEHAVIOR OF 2024 ALLOY

Hou Shu’e, Su Xijiu, Shi Jian, Li Chunyu

1991, 11(2): 53-61.

[Abstract](1373) [PDF 3747KB](178)

Abstract:
The tensile and fatigue as well as stress-corrosion fracture behavior of 2024 alloy at T3510 and T8510 conditions were studied by TSM-35 scaning electron microscopy in this paper.The resultes show that ageing conditions affect the fracture behavior of the alloy markedly.The tensile fracture surface indicates that shear fracture plays a dominant in the fracture processes in T3510 condition.The fatigue cracks were initiated and propagated with the features of the first stage mode and the fracture were faceted and jagged in T3510 condition.The stress corrosion fracture exhibits intergranular fracture in the T3510 condition.The tensile fracture surface exhibits predominatly dimples to nucleate at large Fe-bearing inclusions in T8510 condition.The fatigue cracks were propagated with the second stage mode and the striation could be seen on the surface of the alloy in T8510 condition.The stress corrosion fracture surface exhibits predominatly clearage fan features.

CYCLE CREEP OF SUPERALLOY AND ITS LIFE PREDICTION

Su Hansheng

1991, 11(2): 62-71.

[Abstract](1511) [PDF 720KB](168)

Abstract:
Creep-fatigue life prediction was conducted using strain models or strain energy models.Several strain components which are necessary to predict,were obtained from decomposition of stress-strain closed hysteresis loop.However,hysteresis loop is half open loop for cycle creep.In this case,present paper will describe that the strain components were obtained by means of direct experimental measurement,and can not be got from the loop.The cycle creep behaviour of superalloy also were described.Finally,for ten superalloys at home and abroad, prediction results according to several life prediction models were discussed.It showed that predicting accuracy of SEP-NCM is the best compared with computational results of SEP,SRP,OM,FM models.

1991 Vol. 11, No. 2