Liu
,
B.X. Kang
,
X.G. Cao
,
J.L. Huang
,
B. Yinand H.C. Gu (Institute of Materials Science and Engineering
,
Xi'an Jiaotong University
,
Xi'an 710049
,
China)(Institute of Materials Science and Engineering
,
Xi'an Jiaotong University
,
Xi'an 710049
,
China)( Department of Materials Engineering
,
Luoyang Institute of Technology
,
Luoyang 471049
,
China)( Department of Materials Engineering
,
Luoyang Institute of Technology
,
Luoyang 471049
,
China)( Department of Materials Engineering
,
Luoyang Institute of Technology
,
Luoyang 471049
,
China)( Department of Materials Engineering
,
Luoyang Institute of Technology
,
Luoyang 471049
,
China)
金属学报(英文版)
In this paper; the recrystallization process during aging for a rapidly solidified Cu-Cr-Zr-Mg alloy has been investigated. It is found that the discotinuous crystallization process has been partially retarded by the ultra-fine and dispersed precipitation upon aging after deformation. Thus, a phenomenon of combined in situ and discontinuous recrystallization has been observed in the rapidly solidified Cu-Cr-Zr-Mg alloy.On the nucleation and growth of recrystallization, the precipitated phases are coarscned and dissolved in the front of grain boundaries following a re-precipitation in the recrystallization area,which results in the much more dispersed precipitates.
关键词:
rapid solidification; Cu-Cr-Zr-Mg alloy; aging precipitation; recrystallization
CHAI Huifen WANG Liqin Xi'an Jiaotong Uuiversity
,
Xi'an
,
ChinaLAIRD Campell University of Pennsylvania
,
U.S.A.[Originally published in ACTA METALL SIN(CHINESE EDN)25(3)1989 pp A201—A206
,
Associate professor
,
Xi'an Jiaotong University
,
Xi'an
,
China
金属学报(英文版)
The evolution of dislocation structures in 6% prestrained steel 1018 during fatigue has been studied by TEM.The dislocations are quite movable,the loose cells quickly change to “checkboard”structures,in which the main cell walls lie about {100}.Then,the low energy dislocation structures i.e.dipolar walls and abyrinth structures are evolved.The characteristic of labyrinth and the orientation of dipolar walls are quite similar to fcc crystal.This indicates the energy state of system and the moving ability of dislocations are important factors affect- ing softening process,rather than the slip geometric characteristic of dislocations and details of dislocations.The decreasing in misorientation between adjoining cells and internal stress are discussed.
关键词:
steel 1018
,
null
,
null
CHEN Huangpu DENG Zengjie Xi'an Jiaotong University
,
Xi'an
,
China CHEN Huangpu
,
Lectuer
,
Research Institute for Strength of Metals
,
Xi'an Jiaotong University
,
Xi'an 710049
,
China
金属学报(英文版)
The resistance to crack propagation at earlier stage for a high strength structural steel with certain ductility and its correlation to microstructures,stress states,deformation history and strain characteristics have been investigated.The resistance to crack propagation is mainly de- termined by the plastic constrain ahead of the crack tip,the elastic energy and plastic work absorbed in the stress-strain field.These are connected with the state function of triaxial stress.The deformation history and strain characteristic during deformation of material are described by the flow line in which the deformation history and strain characteristic restrain the crack initiation at stage Ⅱ and the crack propagation at stage Ⅲ.The strain hardening rate may sensitively reflect the stress distribution and micro-fracture mechanism in the interi- or of material.
关键词:
high strength structural steel
,
null
,
null
,
null
CHAI Huifen RUAN Zheng FAN Quncheng (Xi'an Jiaotong University
,
Xi'an
,
China CHAI Huifen
,
associate professor
,
Department of Materials
,
Xi'an Jiaotong University
,
Xi'an 710049
,
China
金属学报(英文版)
The cyclic behaviours of two prestrained materials with different slip modes have been com- pared.From the analysis of hysterisis loops,it is suggested that the decrease in back stress dominates the cyclic process of Cu-Zn alloy with planar slip mode,while the decrease in frictional stress is the main factor affecting the behaviour of Cu with wavy slip mode.The re- lation between the dislocation configuration and internal stress has been also discussed.By means of the relation just mentioned,the variations of dislocation configuration before and after fatigue of the two materials,the differences in their softening mechanism and mechani- cal behaviour could be interpreted.
关键词:
slip mode
,
null
,
null
,
null
SHI Deke LIU Junhai Xi'an Jiaotong University
,
Xi'an
,
China SHI Deke
,
Associate Professor
,
Department of Materials Science and Engineering
,
Xi'an Jiaotong University
,
Xi'an
,
China
金属学报(英文版)
The work hardening of Hadfield manganese steel arises mainly form two causes;1)a large amount of twinning makes perfect dislocations or Shockley dislocations to be blocked at the coherent twin boundaries.2)the deformation leads to strong unsymmetrical distortion due to the occurrence of a large number gf Mn-C pairs or Mn-vacancy carbon-carbon cluster.It has been demonstrated by TEM observation and internal friction tests.As deformation pro- ceeds,the slip constantly accomodates twinning shear giving rise to stress relaxation.Thus, the Hadfield steel exhibits both rapid work hardening and good ductility.
关键词:
twin
,
null
,
null
ZHANG Anfeng Xinjiang Engineering College
,
Urumqi
,
ChinaXING Jiandong LU Wenhua Xi'an Jiaotong University
,
Xi'an
,
China associate professor
,
Department of Mechanical Engineering
,
Xi'an Jiaotong University
,
Xi'an 710049
,
China
金属学报(英文版)
The oxidation behaviour of high Cr Cast iron was investigated at 950 and 800℃ in terms of Cr content in matrix and the amount of carbide.The morphology and types of oxide films and the microstructure of subsurface were also examined.The main conclusions are:1)The original chromium content in the matrix determines the type of oxide film and it is an important factor for the oxidation resistance of high chromium cast iron;2) The oxidation resistance improves with increasing carbide content at 950℃ because of the decomposition of the carbide,while the decompsition of the carbide do not take place at 800℃ so the oxidation resisteance do not improve with increasing carbide volume.
关键词:
high chromium cast iron
,
null
,
null
WU Shanghua LIU Yumen Materials Science Institute
,
Zhongshan University
,
Guangzhou
,
510275
,
China.Department of Materials Science and Engineering
,
Xi'an Jiaotong University
,
Xi'an
,
710049
,
China.To whom correspondence should be addressed.
材料科学技术（英文）
The martensitic transformation in Fe-Cr-W-V-C alloy has been investigated by TEM.The habit plane of martensite is near (252)_f, the austenite/martensite orientation relationship is Kurdjumov-Sachs'.In the martensite plates there are twins on (112)[ 1]_b,dislocation tangles and the lattice defects on (011)_b plane.In the austenite near the growing martensite plates,the dislocations with high density and stacking faults can be observed. The substructure of martensite may probably be the result of accommodation deformation during martensitic transformations.
关键词:
martensite
,
null
,
null
,
null
TAN Yuxu REN Liping LI Gang Xi'an Jiaotong University
,
Xi'an
,
China TAN Yuxu Associate Professor
,
Institute of Metallic Materials and Strength
,
Xi'an Jiaotong University
,
Xi'an 710048
,
China
金属学报(英文版)
In the strengthened layer of stainless steel after shot peening,there are a great amount of deformation microtwins which may act as structural strengthening factor and prevent the gradual relaxation of surface residual stress during fatigue,so as to keep its rather high level of bending fatigue strength.However,in the strengthened surface layer of low carbon steel, dislocation cell structure is so unstalbe during fatigue that its surface residual stress relaxation cannot be retarded.Therefore,the bending fatigue strength of the low carbon steel can not be improred by shot peening.
关键词:
substructure
,
null
,
null
HE Jiawen HU Naisai ZHANG Dingquan Xi'an Jiaotong University
,
Xi'an
,
China Professor
,
Research Institute for Strength of Metals
,
Xi'an Jiaotong University
,
Xi'an 710049
,
China
金属学报(英文版)
Residual stress concentration at a notch depends on both notch geometry and yield strength of the material.It varies through the depth,and its magnitude may be higher than the theoretical one.Compressive residual.stress concentration at the notch of shot-peened specimen of soft material is easily to he relaxed,with the surface damage during shot-peening results in a mi- nor contribution to the fatigue limit.Compressive residual stress increases the crack closure effect at the notch and may lead to a non-propagating crack.
关键词:
residual stress
,
null
,
null
