航空材料学报

INVESTIGATION OF SOLIDIFICATION INTERFACE MORPHOLOGIES AND MICROSTRUCTURES OF A NICKEL-BASE SUPERALLOY

Li Jian-ping, Shi Zheng-xing, Fu Heng-zhi

1986, 6(2): 1-9.

[Abstract](1220) [PDF 6314KB](66)

Abstract:
Using a wider range of G/R，various solidification interface morphologies (Planar, cellular, cellular-dendritic and dendritic)of a nickel-base superalloy K5 have been obtained by means of two direction solidification apparatus, impro-ved high-rate solidification and liquid metal cooling respectively.The precipita-tion rule of principal phases and the relation between interfaces and microstruc-tares arc studied.Experiment shows that the solidification interface of K5 varied with G/f1 ratio and that the condition required for p1ne front solidification is compatible with the criterion of constitutional supercooling.Solidification inter-face morphologies have significant effect on the feaores of both phases precipita-ted during solidification and phases pre:ipitateci post-solidification.Plane frontand cellular solidification can substantialy lower amount of MC, and make -'eutectic form impossibly, but make needle form M6C carbide precipitate easily.The dendritic stucture solidified at high cooling rate have smaller dendrite spasing, smaller segregation and have better microstructures.

RECRYSTALLIZATION OF DA169 ALLOY DURING HIGH TEMPERATURE DEFORMATION

Jin Zhe, Zhou Rui-fa

1986, 6(2): 10-15.

[Abstract](1212) [PDF 3668KB](62)

Abstract:
The recrystallization of DA163 alloy at the several different deformation tem-peratures of 900~1000℃was studied in this paper,The results indicated that the recrystall quantity(q％Vol)of DA169 alloy increased with the deformation temperaturre(T,K)，which folluwed the following equation,q=366.8exp[-1864/T]The necklace structures were found in DA16g alloy owing to the incomplete recrystallization during the deformation of lower temperature.It was observed by optical microscope and ETM that the recrystallizing nucleations formed on/at the old grainboundries, merged each other and growed.The recrystallizing mecha-nism at the lower deformation temperature(1000℃)differed from that of thehigher deformation temperature(1000℃)，that is，at the lower temperature，-phases held back the recrystallizing grainboundric，at the higher temperature, -phase disappeared and the migration of rcerystallizing grainboundries made thecomponents homogeneous in m atrix.

STUDY OF HEAT TREATMENT IN TITANIUM ALLOY Ti-10V-2Fe-3Al

Fu zuo-yi, Wang Jin-you, Wang Xiao-zhou, Duan Jun, Liu Da-wei

1986, 6(2): 16-20.

[Abstract](1140) [PDF 2847KB](65)

Abstract:
The basic characteristics of titanium alloy Ti-10V-2Fe-3A1 are introduced in this paper, it is shown that a %40 weight saving could be accomplished by replacing 30CrMnSiA steel with this alloy in aircraft structures.In this research work an ingot of 280mm in diameter and 250kg in weight was used，the ingot was forged primarily in the beta field and then rolled into the 20mm bar in thealpha plus beta field.A systematical study on the mode of solution treatment，The effecy of solution treatment temperature and the effect of the temperature and the time of the aging was carried out. The results indicate that using a solution treatment in the alpha plus beta field ang a alpha the most excellent combinate of tensile properties and fracture toughness could be obtaiined.

INVESTIGATION OF SOLIDIFIC ATION PROCEDURE FOR SINGLE CRYSTAL DD3

Zheng Yun-rong, Ruan Zhong-ci

1986, 6(2): 21-28.

[Abstract](1218) [PDF 5175KB](68)

Abstract:
The liquidus and last sclidification temperature of single crystal DD3 is higher about 23℃ and 60℃ than those of alloy K3, respectively.As Ti content decrcase，to 1,5%，the eutectic(+')in alloy can be eliminated.This makes Iiquidus and solidus rise 10℃ and 60℃ further.The effect of C on solidus ana liquidus is not nearly large as Zr and B.In some degree the influence of C is inferior to Ti.The single crystat alloys withlow Ti and without eutectic(+)have superior CaStabiliy.

THE SOME CHARACTERISTICS OF RAPIDLY SOLIDIFIED ALUMINIUM ALLOY POWDER PARTICLES

Pan Ming-xiang, Yu Qui-fu

1986, 6(2): 29-35.

[Abstract](1232) [PDF 4553KB](68)

Abstract:
The relationship between dendritic arm spaces and cooling rate powder par-ticie size of rapidly solidified Al-Zn-Mg-Cu system aluminium alloy powder parti-cles has been evolved,The experienced formula of relationship between powder particles size (dP)and dendritic arm spaces (ds)is ds=61 ds2.323.The effect of rapidly coolingon aluminium alloy powder particle microstru-ctures has been studied by metallograph and scan electronmicroscope.Whth the cooling rate exceeding 10℃ 2℃/s, rapid solidification could form metastablc microstructure

THE HYBRID EFFECT CONTRIBUTION TO TENSION BEHAVIOUR OF UNIDIRECTIONAL COMPOSITE

Song Huan-chang, Zhang Zuo-guang

1986, 6(2): 36-42.

[Abstract](1201) [PDF 3422KB](87)

Abstract:
The Paper analyse the tension behaviour of two play- Hybrid composites.The theory of equation used hybrid effect ratio is corrected.The equation of this theory are in good agreement with experimental result

FATIGUE CRACK GROWTH BEHAVIOUR OF 7475-T7351 ALUMINIUM ALLOY UNDER CONSTANT AMPLITUDE LOADING

Zhang shi-jie, Nowack·H

1986, 6(2): 43-49.

[Abstract](1240) [PDF 3703KB](72)

Abstract:
Constant amplitude fatigue crack growth tests were performed over a wide range of R-ratios on center cracked 8 mm thick Al 7475-T7351 specimens.In consideration of that making a determination of crack opening stresses is important for the crack growth life prediction based on the crack ciosure concept and it is necessary to find a way that is convenient to determine the effc-dive stress intensity factor range Keffin engineering practice, this paper derived the empiriacl crack opening stress expression of the material used in This investigation from the crack growth rate data da/dN.Consequently the crack growth behaviour of a wide range of R ratios can expresse dunitedly by the effective stress intensity factor range Keff.It is found that dimensionless crack opening stresses decrease as the applied maximum stress level increases.Fracture analysis results indicated that the fracture transition from tensile mode to shear mode during the test was controlledmainly by Keff and a opmaxvaluesincrease as cracks growth from the tensile mode to the shear mode.

NVESTIGATION OF FRACTURE CHARACTERISTICS FOR CARBON BUNDLE AND COMPOSITES USING ACOUSTIC EMISSION TECHNIQUE

Wei Xing, Yuan Zhen-ming, Deng Ri-hong

1986, 6(2): 50-54.

[Abstract](1280) [PDF 2430KB](69)

Abstract:
t has important significance to study mechanical properties of carbon fiber，because mechanical processes，of carbon fiber have great effect on that of compositcs and It's fracture processes.The paper presented have studied longitudinal mechanical Properties, specially that correlated with fra:cturr behavior，for carbon bundle by means of acoustic emission(AE)techniqucs.The distribution of fracture elongation for T-300 carbon f ibcr was obta」nedusing AE.It approached to.,Weibull distribution and logarithmic normal distribution of fracture elogation for carbon fiber was measured using AE.We investigated frequrency spectrum of AE signal from carbon bundle during damage processes and observed a obvious characteristic for frequcy spectrum.

INVESTIGATIOIN ON THERMAL RESIDUAL STRESSES INTRODUCED DURING CURING OF CARBON/EPOXY COMPOSITES IN ACOUSTIC EMISSION TECHNIQUE

Fu Huanbo, Ni Rong-gen, Ren Rong-zhen, Fan Tang

1986, 6(2): 55-61.

[Abstract](1239) [PDF 2430KB](65)

Abstract:
Thermal residual stresses introduced during curing of carbon/epoxy composites were investigated with the use of acoustic emission(AE)technique.The laminates of T300/648 epoxy.BF3MEA with different ply-angle[0/].4scopled at different rates(0.5. 1.0. 1.5, 2.0℃/min)were used as specimens.AE monitoring during curing shows the capability of identifying the structural .changes of composites in the entire curing cycle,It is observed that AE can also be used to determine the residual stresses introduced in the curing cycle qualitatively.Microscopic observations of the cross-sections of the laminates indicate that there is no void and micro-crack in the laminates.The results of flexual and interlaminar shear strength show that the influence of cooling rate on the mechanical properties of laminates is not obvious.Therefore, it can be seen that the residual stresses resulting from different ply-angles and cooling races are not big enough to make cracks in the laminates, so the mechanical properties of the laminates are not remarkably affected by the ply-angle and cooling rate under the condition of this work.

THE EFFECT OF COOLING RATE ON THE FINE SCALE STRUCTURE OF THE 40CrMnSiMoVA STEEL

Zhong Bing-wen, Wang Guang-sheng

1986, 6(2): 62-67.

[Abstract](1178) [PDF 4017KB](59)

Abstract:

A STUDY OF THE EFFECT OF THERMAL CHEMICAL THEATMENT ON STRUCTURE AND PROPERTIES OF CAST Ti-6Al-4V ALLOY

Xue Zhi-yang, Wang Ding-hua, Wang Jin-you

1986, 6(2): 68-70.

[Abstract](1082) [PDF 1891KB](60)

Abstract:

APPRONCH OF PROJECTING BACK TO EQUIVALENT INITIAL FLAW SIZE (a₀)FROM FRACTOGRAPHY

Chen Ying, Liu Cai-mu

1986, 6(2): 71-76.

[Abstract](1130) [PDF 3647KB](65)

Abstract:

1986 Vol. 6, No. 2