航空材料学报

INFLUENCE OF Hf CONTENT ON SEGREGATION BEHAVIOR AND MECHANICAL PROPERTIES OF DIRECTIONALLY SOLIDIFIED SUPERALLOY DZ22

Wang Luobao, Chen Rongzhang, Wang Yuping

1989, 9(2): 1-7.

[Abstract](1463) [PDF 745KB](167)

Abstract:
Test results show that Hafnium is a strong segregative element. Hf-addition in alloy DZ22 reduces the dendrite segregation of other elements and alters the relative content of alloying elements Ti, W, Nb and Cr in various phases. As Hf is added into the alloy the volume fraction of γ/γ′eutectic is increased and the temperature range between solidus and liquidus is expanded, which may maintain the effective linkage of interdendritic capillary feeding channel, thus improving the resistance of DS castings to the thermal cracking. With increasing Hf content the stress-rupture properties, in particular, the transverse stress-rupture properties of alloy DZ22 at intermediate temperature are obviously enhanced.

COMPUTER MODELLING AND CONTROL OF HRS DIRECTIONAL SOLIDIFICATION PROCESS OF Ni-BASE SUPERALLOYS

Shi Zhengxing, Mao Xieming, Chen Juhuan, Chen Huochun, Guo Tao, Fu Hengzhi

1989, 9(2): 8-15.

[Abstract](1458) [PDF 1356KB](182)

Abstract:
In this paper, a two-dimensional transient thermal model of a plate sample is established by computer-modelling the HRS directional solidification process of Ni-base superalloys. Using the model, a control-system based on a single board computer TP801B is built up to real time control the location of solid/liquid interface in HRS directional solidification process. The result shows that the solid/liquid interface of controled samples tends to insulating plate rapidly and locates near it steadily. Thus it is effective to increase and stabilize the temperature gradient in the liquid ahead of the solid/liquid interface, also improve the macro-and microstructure.

THE HEAT-TREATMENT AND MICROSTRUCTURE OF LOW EXPANSION SUPERALLOY INCOLOY 903

Shang shixian, Jian Guizao

1989, 9(2): 16-24.

[Abstract](1405) [PDF 1816KB](182)

Abstract:
Incoloy alloy 903 is a precipitation hardened Ni-Fe-Co alloy with outstanding characteristics: low coefficient of thermal expansion, nearly constant modulus of elasticity and higher strength. The X-ray diffraction transmission electron microscopy and optical microscopy are used to study the microstructure in Incoloy 903 after different soultion treatment and aging, as well as the η phase precipitation rule. Results have shown that the recrystallized structure can be obtained after solution treatment above 880℃ and the“hot-working structure”below 850℃. The fine dispersion and optimum strengthening effect of γ′phase can beachieved by aging at 690-720℃ for 8-16h.

THE MECHANICAL PROPERTIES OF KEVLAR FIBRE AND “YIELDING” BEHAVIOUR OF ITS HYBRID COMPOSITES

Song Huancheng, Zhang Zuoguang, Deng Hao

1989, 9(2): 25-31.

[Abstract](1508) [PDF 615KB](192)

Abstract:
The mechanical properties of Kevlar fiber as well as the“yielding”behaviour of C/K, K/G interply hybrid composites in bending was analyzed and the “yielding”loads and stresses on such materials were theoretically estimated. Meanwhile, an acoustic emission method is used to monitor and verify the“yielding”damaging process,

VIBRATION FATIGUE CHARACTERISTICS OF TITANIUM ALLOY TC6 WITH VARIOUS MICROSTRUCTURES

Tao Chunhu, Zhang Shaoqing

1989, 9(2): 32-38.

[Abstract](1367) [PDF 1577KB](136)

Abstract:
The vibration fatigue characteristics of TC6 titanium alloy with Widmanstatten, basket-weave, equiaxed and duplex microstructures have been studied. The duplex microstructure has the excellent vibration fatigue properties and the others have approximately the same fatigue life. The precipitation of Ti3Al phase has been found in Widmanstatten, basket-weave and equiaxed microstructures. The fatigue crack propagation paths and the deformation characteristics around fatigue crack tips were examined.

THE INFLUENCE OF Fe,Si IMPURITY CONTENTS ON THE MICROSTRUCTURES AND PROPERTIES OF 2024 SERIES Al ALLOYS

Wang Shuncai, Li Chunzhi, Zheng Yuzhen, Jin Yan

1989, 9(2): 39-47.

[Abstract](1491) [PDF 1979KB](160)

Abstract:
In this paper, the structure, dissolution, formation of the coarse and dispersoid phases in 2024 series Al alloys and their influence on the properties of the alloys with different impurity contents and at various heat treatment conditions, was studied using optical and quantitative metallography, electron probe analysis(EPA)and transmission electron microscopy(TEM). The major portion in coarse phases is α—Al12Fe3Si(b.c.c.). Generally, dispersoid phase(T phase)was suggested to be A120CU2Mn3 phase, with the Cmcm space group. However our electron diffraction analysis has deterimined that the T phase is with the Bbmm space group and parameters of a=24.19Å, b=12.51Å, c=7.86Å, which is a rod-like phase with axis along〔010〕direction, and forms the ten-twin easily. The coarse phases have a little effect on tensile properties, but have obvious effect on fracture toughness which decreased with an increase of the amount of the phases contained.

WELDABILITY OF NICKEL-BASE SUPERALLOY GH536 SHEET

Li Mengnie, Hou Yunian, Zhang Weiqin, Zhang Qi

1989, 9(2): 48-55.

[Abstract](1540) [PDF 1076KB](374)

Abstract:
In order to meet the need of manufacturing welded components used in combustion chambers of a newly designed aeroturbine, the weldability of nickel-base superalloy GH536 sheet is investigated in this paper. The cross-lap joint cracking test and hot ductility test are conducted to evaluate the crack sensitivity of the alloy. The data of mechanical properties of GTA welded joints have been provided in this paper. The results of this investigation show that the weldability of superalloy GH536 is better than that of superalloy GH44 used in the past and su-peralloy GH536 can take the place of GH44 during the development of the newly designed aeroturbine.

AN ANALYSIS OF THE WAVEFORM OF ACOUSTIC EMISSION SOURCE AND ITS APPLICATION

Yuan Zhenming

1989, 9(2): 56-60.

[Abstract](1420) [PDF 304KB](143)

Abstract:
The analysis principle, calculating method and their application of the waveform of acoustic emission source are summarised in this paper, and the final analysis result of several materials are provided.

1989 Vol. 9, No. 2