航空材料学报

Influences of the Remnant Dendrite on the Service Propertice for Turbine Disc of GH36 Alloy

Zhou Reifa

1983, 3(1): 1-7.

[Abstract](1524) [PDF 5027KB](63)

Abstract:
In present paper has investigated the effects of remnant dendrite on the ten-sile strength、impact ductility,stress-rupture life、the fatigue life under the high cycle and low cycle、fracture toughness for turbine disc of GH36 alloy.It is given out the relation between the low cycle fatigue fracture life (Nf) and the steady tensile stress (st) in the presence of remnant dendrite as follows. LgNf =a + blgst b0 Experimental results show that ramnant dendrite marked decrease value of fracture toughness (Klc) for turbine disc of GH36 alloy. In this paper, the critical crack length (ac) was computed in accordence with equivalental stress (eq) and Kic of turbine disc by means of paris, formula. In this paper, the several factors effecting such as. cooling rate of ingot、forging ratio were also discussed. Finally, its also presented the proposal of the quality control standard for turbine disc of GH36 alloy.

Study of Superplasticty of Ti679 Alloy

Yang Zhenheng, Su Zuwu, Zhou Yigang, Chen bhisun

1983, 3(1): 8-12.

[Abstract](1511) [PDF 3344KB](54)

Abstract:
In thi?s paper, the superplastical forming conditions of Ti 679 alloy are studied.The testing results expressed that in the range of temperature from 720℃ to 900℃ this alloy has superplasticity and its value of m is heigher than 0.3. In the range of temperature from 800℃ to 850℃ this alloy has heigher superplasticity. At 850℃ and the strain rate of 6.6710-4sec-1, the superplasticity of this alloy is best and its elongation is 734%, and its value of m is 0.43. In paper, the relative curves of the deforming temperature、strain rate、 elongation and deforming resistance are given also.These curves may be used as the reference for determing the technological specification of superplastical forming.

The Effect of Rare Earth Elements on the Microstructures and Properties in Aluminium-Copper Cast Alloys

Cheng Jianiag, Yu Guifu

1983, 3(1): 13-16.

[Abstract](1536) [PDF 6648KB](93)

Abstract:
In this paper, an investigation of the effect of rare-earth elements on the microstructures and the tensile and stress-rupture properties in Al-Cu cast alloys was described.lt was found that the addition of rare-earth in Al-Cu system alloys, promoted a preferential formation of intermetallic compounds along the grain boundaries accompaning by a dilution of copper content in the matrix.In order to acquire an optimum properties of Al-Cu alloys, it is necessary to keep a proper proportion of the copper to the mishmetal content. The influence of complemental strengthening elements#Mn and Zr and the strengthening mechanism of rare-earth addition in Al-Cu system alloys were also discussed.

Investigation of Silicon Carbide Fiber Reinforced Aluminium Composites

Wei Ketai, Huang Dadun, Zhao Xun

1983, 3(1): 17-22.

[Abstract](1446) [PDF 4033KB](75)

Abstract:
This paper is a research report about aluminum composite reinforced with silicon carDide f iber.Using pressing liquid-infiltration in vacuum, the composite plate has been made of home aluminium foil and continuous silicon carbide fiber made in Nippon Carbon Company. The fibers were not seriously damaged and were separated well, so that the composite plate performance is good. The longitudinal tensile strength reached ROM value nearly and the transverse strength is over prediction value in a part of composite specimens. The relation between strength of composite and volume fraction of fiber was determined. The fracture surface morphology was analysed by scanning electron microscope The metallurgical analysis of transverse tensile specimens was made also. The interface strength was discussed briefly.

Effect of Minor Alloying on the Solidification Process of Superalloy K5

Zheng Yunrong, Cai Yulin, Gao Ping

1983, 3(1): 23-29.

[Abstract](1515) [PDF 5045KB](75)

Abstract:
In this paper, solidification sequence of four primary phases, MC, M3B2, eutectic (+) and Ni5Hf, was determined, the percent of solid and liquid of four alloys at diffei ent temperature in the range of solidus and liquidus was measured and the effect of alloying elements C, B, Hf on solidification process was explored for a single crystal superalloy K5 as well as alloy K5 in which C, B, Hf were alone added. The results showed that B and Hf promote the formation of low melting point phases, M3B2 and Ni5Hf, in solidification process of alloys and widen the range of solidus and liquidus obviously. Liquid of interdentritic zones are interlinked each other in a very wide range of temperature for Hf-or-B-bearing alloys, therefore this improves castability. Effect of C on solidification character of alloys is not obvious, but it influences the precipitation of carbide distinctly.Besides precipitation of MC(1) rich in Ti above 1270℃, MC(2) rich in Hf also precipitates below 1240℃.

The Influence of Epoxy Resin with Different Molecular Weight on the Curing Process and the Properties of Composites

Nie Jiayang, Shih Shufang, Yu Zhennan

1983, 3(1): 30-35.

[Abstract](1527) [PDF 3662KB](81)

Abstract:
It is apparent that the influence of resin with different molecular weight and molecular weight distribution on the curing process and the properties of compo-sites by way of HPLC, DSC, TGA, DMA, viscoelasticimeter and other usual methods. The experiments result in that the epoxy resin with lower molecular weight has longer gel time, larger flow, higher Ta and Tb, lower AH, lower heat resistance (such as HDT, Tg, the temperature of heat degradation, weight loss) and lower retention of Young's Module at 50℃.

Fatigue Crack Propagation in Glass/Epoxy Composites

Zhang Hushan, Nadeau, J.S. Teghtsoonian, E.

1983, 3(1): 36-40.

[Abstract](1588) [PDF 3368KB](72)

Abstract:
Compact tension specimens of cross-ply non-woven, and woven glass/epoxy composites were subjected to tension-tension cyclic loading. The rate of crack growth was monitored with a travelling microscope. Crack morphology and fracture surface appearance were examined by optical and electron microscopy. The crack shape in interior plys was determined by burning oft the resin. The crack growth rate was found to be controlled by the applied stress intensity in much the same way as with some metals and some plastics.The slope of the paris plot, (log da/dN versus logK) was 6.8 for the composite made from non woven glass and 10 lor the composite made from woven glass. The fatigue crack surface appearance was found to be quite different from the fast-fracture surface. The amount of fiber debonding and pull-out was greater on the fatigued surface.

A Study of Low-cycle Thermal Fatigue Behavior of the Superalloy GH33A

Wang Haiqing

1983, 3(1): 41-46.

[Abstract](1491) [PDF 3400KB](60)

Abstract:
The thermal - mechanical fatigue (TMF) and low-cycle fatigue (LCF) behavior of a superalloy GH33A has been investigated at 330与700℃ and 700℃. The TMF results show the plastic strain range p and half stress range /2 to be related to the endurance by the Coffin-Manson power law p= 0.054Mf-0.054 /2=1.97Nf-0.074 The fatigue-hardening was found to situate at an early stage.The half stress range /2 is related to half plastic strain range ep/2 by /2=1.9(p/2)0.14 The temperature cycle reduced the endurance and promoted intergranular fracture. This experimental results may be considered as a theoretical base for the material selection and design of components of turboengines.

An Investigation of Fatigue-Crcep Curve and Fracture Map

Chen Guoliang

1983, 3(1): 47-52.

[Abstract](1443) [PDF 4115KB](74)

Abstract:
This paper introduces a fatigue-creep curve and fracture map constructed on the basis of the fatigue-creep curve.These curves and maps are not only effective as a rough guide in engineering design (e. g. by providing for a given fatigue-creep interaction condition information of which deformation and fracture mechanism predominates)， but are also very useful as a means of studying the effect of various factors on the mechanical behavior of alloys. Furthermore it provides a set of data of mechanical properties of alloys for a stress condition approximated to certain real service condition.

Notch Strength of Metals

Zheng Xiulin

1983, 3(1): 53-58.

[Abstract](1533) [PDF 4206KB](76)

Abstract:
Models are proposed for explaining the crack initiation at notch root and the fracture of the notched element. Then，approximate formulas are developed for predicting the notch strengths of different kinds of metals. The formulas developed are checked by analysing anew suitable available test data concerning notch strength. A new material constant, the so-called nonsensitive-to-notch factor, whose value can be predicted from the tensile properties of metals, is tentatively proposed.

A Simple and Convenient Method of Interpreting the Laue Diffraction Pattern in Determining Orientation of Cubic Cryctals

Zhang Guohuan, Wang Qingsui

1983, 3(1): 59-64.

[Abstract](1515) [PDF 4165KB](83)

Abstract:
If the Laue method is used to determine crystallographic orientation of the crystals, some obvious changes will take place in intensity, shape and number of Laue spots on the film, which is obtained, due to effects of the composition in alloy and tlie condition of a sample.This phenomenon will create some difficulties for interpreting the back-reflection Laue pattern. This paper recommends a characteristic triangles of back-reflection Laue pattern according to the symmetric feature of cubic crystals. A few spots, which are selected from the Laue pattern photograph, can be used to determine the crystal orientation quickly, easily and accurately.It is unnessessory to use any manual table in this method. Some good results will be acquired if anyone keeps in mind the angle values between two planes as well as two zones of these characteristic triangles.

The Short Crack Problem

K.J.Miller

1983, 3(1): 65-72.

[Abstract](1496) [PDF 5284KB](82)

Abstract:
The problems associated with short crack growth, defined as situations in which the intensity of the crack tip field is underestimated by linear elastic fracture mechanics analyses, are briefly reviewed. Two cases are identified,cracks growing in plastically strained materials,such as occurs in high strain fatigue studies and at notch roots, and small cracks growing in single grains as occurs close to the fatigue limit in plain specimens. Important mechanical and metallurgical features of short cracks are discussed with particular reference to the upper and lower bound definition of a short crack.

An Investigation of Toughening Epoxy Resin with CTBN

Li Yongde, Zhao Shiqi, Sun Yishi

1983, 3(1): 73-74.

[Abstract](1423) [PDF 1540KB](70)

Abstract:

Moniloring Cure Process of Composites by Dynamic Dietectric Analysis Technique

Li Xingzhou, Shen Rongying, Man Shupeng, Tu Shicun

1983, 3(1): 75-77.

[Abstract](1435) [PDF 16388KB](47)

Abstract:

News About ISO/TC20/SC11 Meeting

1983, 3(1): 78-78.

[Abstract](1505) [PDF 14063KB](40)

Abstract:

1983 Vol. 3, No. 1