航空材料学报

THE STABILITY OF TiAl ALLOY LAMELLAR STRUCTURE WITH DIFFERENT Ti/Al RATIO

Zhang Ji, Zhang Jianwei, Zou Dunxu, Zhong Zengyong, Zhang Zhihong, Zeng Meiguang

1996, 16(1): 1-5.

[Abstract](1393) [PDF 633KB](155)

Abstract:
The stability of TiAl alloy lamellar structure in thermo-exposure has attracted extensive attention recently.This paper conducted the observations and analyses on the transformation of the lameller structures in 1323K thermo-exposure.It's revealed that the Ti/Al ratio has significant effects on the stability and decomposition mechanisms of the lamellar structures.The lamellar structure with Ti/Al ratio properly higher than 1:1 can have much better stability.

HOT CRACKING TENDENCY OF DIRECTIONALLY SOLIDIFIED Rene125 ALLOY

Ding Hao, Fu Hengzhi, Liu Zhongyuan, Chen Rongzhang, Liu Bocao, Zhong Zhengang, Tang Dingzhong

1996, 16(1): 6-11.

[Abstract](1612) [PDF 349KB](213)

Abstract:
A semi-quantitative method was proposed to evaluate hot cracking tendency.Good repeatibility of this method was proved by the hot cracking result of directional solidification experiments.Hot cracking tendency of directionally solidified Rene125 alloy was studied through hot cracking experiments carried out in different directional solidification conditions.It was discovered that hot cracking tendency of directionally solidified Rene125 alloy can be influenced by drawing rate,furnace temperature and casting temperature.

INVESTIGATION ON SHOT PEENING STRENGTHENING OF A POWDER METALLURGY SUPERALLOY RENE'95

Ru Jilai, Wang Renzhi, Li Xiangbin

1996, 16(1): 12-18.

[Abstract](1541) [PDF 578KB](122)

Abstract:
The relationship between residual stress field,microstructure,density in the surface shot peening layer and the fatigue behavior for hot isostatically pressed(HIP)powder superalloy Rene'95 have been investigated.It has been shown that the high cycle and the low cycle fatigue strength can be obviously improved by shot peening.

INVESTIGATION OF PHASE TRANSFORMATION TEXTURES AND THEIR INFLUENCE FACTORS IN TITANIUM SHEET

Zhu Zhishou, Yan Minggao, Gu Jialin, Chen Nanping

1996, 16(1): 19-25.

[Abstract](1488) [PDF 419KB](159)

Abstract:
The influence of cold rolling reductions,annealing and cyclic phase transformation treatments on formation of phase transformation textures in titanium sheet,has been investigated by means of crystallite orientation distribution function(CODF)analysis.The results show that,the cold rolling reduction has a great effect on the development of phase transformation textures.In cold rolled and recrystallization annealed titanium sheet,a more random texture distribution has formed after α→β→α phase transformation.The phase transformation texture[2110] ND,formed after 1 cycle of α→β→α phase transformation,has been inherited through 3 cycles of α→β→α phase transformation.

INFLUENCES OF LIQUID SUPERHEATING TREATMENT ON THE STRUCTURE AND MECHANICAL PROPERTIES OF HYPEREUTECTIC Al-Si ALLOYS

Gui Manchang, Jia Jun, Li Qingchun

1996, 16(1): 26-31.

[Abstract](1486) [PDF 705KB](251)

Abstract:
The influences of liquid temperatures on the primary silicon structure and mechanical properties of hypereutectic Al-Si alloys containing high silicon level,in various cooling rate conditions,have been studied.Experimental results showed that high temperatures can obviously changed the primary silicon structure,and increased tensile properties and wearability under the condition of high cooling rate.The phenomena were attributed to the change of the liquid structure of the Al-Si alloy due to liquid temperature increase.

MICROSTRUCTURE AND MECHANICAL PROPERTIES OF POWDER FORGING STEEL 12Cr2Ni4A AND 18Cr2Ni4WA

Li Zongxia, Zou Zhongyuan, Xie Shixu, Cai Jinyu, Jiang Yishou

1996, 16(1): 32-37.

[Abstract](1428) [PDF 459KB](235)

Abstract:
Microstructure and mechanical properties of powder forging steel 12Cr2Ni4A and 18Cr2Ni4WA are described in this paper.Forging powder steel 12Cr2Ni4A with 0.08～0.12%C and less than 0.2% O2,18Cr2Ni4WA with 0.11～0.16% C have better mechanical properties.Toughness of powder forging steel can be increased efficiently by diffusion annealing in longer time.

PREVENTION OF SOLIDIFICATION CRACKING IN WELDS WITH AUXILIARY HEAT OR COOL SOURCE

Wu Aiping, Ren Jialie, Lu Anli

1996, 16(1): 38-46.

[Abstract](1339) [PDF 557KB](189)

Abstract:
Controlling the strain of weld metal during solidification is one of the effective methods to prevent solidification cracks in weld.In this project,the effects of auxiliary heat or cool sources on the temperature distribution,the tensile strain of weld metal during solidification as well as on the microstructure,hardness of joint are studied with numerical analysis and experimental methods.The results indicate that the auxiliary heat sources can effectively decrease the tensile strain of weld metal during solidification and prevent solidification cracking.Auxiliary cool source can also decrease the tensile strain,but its effect is less than that of auxiliary heat source.Auxiliary heat and cool sources have no distinct effects on the microstructures,hardness and crystal sizes of joints.

STUDY ON NOMEX HONEYCOMB APPLIED TO Z9 HELICOPTER

Li Yong

1996, 16(1): 47-54.

[Abstract](1540) [PDF 613KB](434)

Abstract:
A study on the materials,technology,physical and mechanical properties of Nomex honeycomb for Z9 helicopter is presented in this paper.The brittleness and the technology have been modified.The mechanism and approach to improved the comprehensive properties by using the large-area and small cell size Nomex honeycomb are discussed.

THEORETICAL AND EXPERIMENTAL STUDY ON THE IOSIPESCU SHEAR TEST METHOD

Zhang Zilong

1996, 16(1): 55-60.

[Abstract](1576) [PDF 373KB](406)

Abstract:
The development of the shear test methods of composite materials,performed by double V notched specimens was discussed in the present paper.FEM was used to investigate various factors which have great influences on the shear stress distribution in the guage area of specimens.Experimental procedures were performed on both unidirectional and π/4 laminates.The results show that the method can be used to generate the test data of shear properties well.

1996 Vol. 16, No. 1