航空材料学报

AN ADVANCED ELEVATED TEMPERATURE TITANIUM ALLOY MODIFIED BY A RARE EARTH ELEMENT

Deng Ju, Wu Zhiyue

1990, 10(1): 1-7.

[Abstract](1424) [PDF 1197KB](217)

Abstract:
This article briefly introduces the characteristics of microstructure and properties of a new elevated temperature titanium alloy-Ti-633G,developed by Northwest Institute for Non-ferrous Metal Research(NINMR).The nominal composition of Ti-633G alloy is Ti-6.5Al-3Sn-3Zr-1Nb-0.3Mo-0.2Gd.The alloy Ti-633G was developed by adding a small amount of rare-earth element gadolinium (Gd) based on IMI829 alloy.The alloying design was placed emphasis on an optimized balance among creep resistance,post-creep stability and fatigue properties.Ti-633G is a near-alpha alloy.Added 0.2wt% Gd into IMI829 alloy enable β average grain size to decrease from 550μm to 100μm,and restrain the grain growth at high temperatures.There are three kinds of Gd2O3 structures and S2-type silicide——(Ti,Zr)6Si3.In the paper,the tensile properties,creep resistance,fatigue properties and post-creep stadility of Ti-633G were compared with those of IMT829.The roles of rare-earth element Gd in elevated temperature titanium alloys were discussed.Ti-633G is an“inherent fine grain”elevated temperature titanium alloy,which can be used in gas turbine engine up to about 550℃.

EFFECT OF THE CARBON CONTENT ON THE MICROSTRUCTURE AND MECHANICAL PROPERTIES OF GC-4 STEEL

Zhon Ping, Zhang Lianyong

1990, 10(1): 8-14.

[Abstract](1394) [PDF 1330KB](223)

Abstract:
The effect of carbon content within 0.38% to 0.40% on the microstructure of GC-4 ultra-high strength steels after isothermal transformation and low temperature tempering has been studied in the present investigation,and the relationship between the microstructure and mechanical properties of the steels has been discussed.The results show that the steels with the carbon content lower than 0.40% have better strength-toughness conbinations than those with the carbon content greater than 0.40%.It has been found that with the further increment of carbon content the ultimate tensile strength increased slightly,but the yield strength of the steel showed the decreasing trend.Therefore,in order to obtain a better conbination of strength and toughness,it is reasonable that the carbon content of GC-4 steel should be controlled below 0.40%.

AN INVESTIGATION OF HIGH-OUALITY CASTING OF HIGH-STRENGTH ALUMINIUM ALLOY ZL205A FOR EXTERNAL BEAMS FOR ATTACK BOMBER

Cai Wenyu, Liu Baichao

1990, 10(1): 15-25.

[Abstract](1389) [PDF 801KB](216)

Abstract:
In this paper some bulk complexly shaped castings of high strength aluminium alloy ZL205A for external beam of attack bomber are investigated.Due to their structure complexity,long and flat configuration,and deformability,the metallurgical quality and relative stability of demension are the problems to be resolved.The casting process,design of mould,installation of chiller,melting and heat-treatment are also sumerized.Therefore the mechanical properties of casting and cutting specimen can meet the design and application requirements and acceptance percentage of qualitified castings reaches about 85%.

INVESTIGATION ON SERVICE OF SUPERALLOY FOR TURBINE DISK

Zhou Ruifa

1990, 10(1): 26-33.

[Abstract](1371) [PDF 628KB](244)

Abstract:
Some fuilure cases,metallurgical flaws,service property and calculated lifetime of surperalloy for turbine disk at the several different kinds (types) of turbine engines were discribed in this paper. The wide range of investigations shown shut lower yield strength,coarse grain size and metallurgical flaws were the basic causes for the earlier failure of superalloy for turbine disk.With this paper we can use the results of simulated testings to calculate the lifetime of turbine disk.

THE INVESTIGATION OF THE NUMERICAL CONTROL AND THE MODELLING FOR SUPERALLOY IN DIRECTION SOLIDIFICATION

Zhang Kefu, Fu Hengzhi

1990, 10(1): 34-37.

[Abstract](1365) [PDF 248KB](145)

Abstract:
This is a brief description of the method to model and control the directional solidification of superalloy by using computer.The possibility about the application of the described method,as well as its effect upon the directional solidification and the microstructure of superalloy samples were investigated.The results showed that directional solidification could simulated realistic and be controlled effectively by computer,and that the microstucture of directional solidification was improved.

COATING-SUBSTRATE SYSTEM AT ELEVATED-TEMPERATURE PROCESS

Zhao Jiapai, Zhao Saizhen, Li Fengmei

1990, 10(1): 38-45.

[Abstract](1374) [PDF 940KB](171)

Abstract:
This paper discusses the mechanism of protection against oxidation of coated materials at elevated temperature.The high temperature processon interface between coating and substrate is as follows,oxygen diffuses through coating onto substrate,then it results in oxidation of alloy elements. The performance of coating is to reduce diffusion of oxidizing atmosphere, thus it also reduce pauperization of Cu,but it is out of function for Ti and Al. Besides,there is small amount of Si to permeate into substrate,its thickness is about 0.2mm after duration of 1000hrs at 1100℃. Besides oxidation,no other resultant of reaction has been found along interface between coating and substrate.

APPLICATION OF OPTIMIZING COMPUTATION TO CREEP-FATIGUE LIFE PREDICTION

Su Hansheng

1990, 10(1): 46-52.

[Abstract](1347) [PDF 451KB](148)

Abstract:
For CP type creep-fatigue test life prediction,a numerical computational method was proposed by author,namely,in order to obtain parameters Xi(i=1,4) of prediction equation N-1=(σT·Δεp)x2/x1+(σT·Δεc)x3/x4,optimizing approach of parameters was adopted.Thus,it not only can save cost and simplify test procedure,but also proves that the numerical computational method of SEP is better than the current SEP method in prediction accuracy and prediction capacity.

DEVELOPMENT OF Ni₃ Al AND ITS ALLOYS

Han Yafang

1990, 10(1): 53-66.

[Abstract](1516) [PDF 1008KB](180)

Abstract:
In this review,the mechanism of grain boundary brittleness of polycrystalline Ni3Al and its improvement is first discussed,followed by the solid solution strengthening of Ni3Al single phase,and finally the development of Ni3Al base superalloys will be involved.

1990 Vol. 10, No. 1