材料期刊网

THERMAL FATIGUE CRACKING IN STEEL 5CrMnMo

HE Shiyu LI Ying LIU Jianhong Harbin Institute of Technology , Harbin , China HE Shiyu , Faculty of Metal , Harbin Institute of Technology , Harbin , 150006 , China

金属学报(英文版)

The thermal fatigue behaviour of steel 5CrMnMo after various heat treatments has been examined by means of Coffin-model and self-strained thermal fatigue testing machines.The thermal fatigue crack initiation and propagation have been observed under SEM and TEM. The majority of thermal fatigue cracks of the quenched samples initiated firstly at the grain boundaries and that of the quenched-tempered samples at the breakage interface of the car- bide and matrix.The thermal fatigue cracks of either quenched or quenched-tempered steel propagated mainly along the breakage interface of carbide and grain boundaries.

关键词: thermal fatigue crack , null , null

CONTACTING FATIGUE FAILURE OF Cu-22%Pb PLAIN BEARING ALLOY

JIA Jun CHEN Xianchao Harbin Institute of Technology , Harbin , China [Originally published in ACTA METALL SIN(CHINESE EDN)25(3)1989 pp A232—A234 , Associate Professor , Scientific Research Office , Harbin Institute of Technology , Harbin , China

金属学报(英文版)

The results of the contacting fatigue tests for Cu-22%Pb plain bearing alloy show that the fa- tigue failure behavior of the alloy is related to the distribution of Pb particles.Both the addi- tions of mischmetal and sulphur can refine the Pb particles.However,mischmetal improves and sulphur deteriorates the fatigue property of the alloy.

关键词: Cu-Pb alloy , null , null , null

RECRYSTALLIZATION-INDUCED PLASTICITY IN 18Ni MARAGING STEEL UNDER ELASTIC STRESS

YIN Zhongda Harbin Institute of Technology , Harbin , China ZHOU Yongkang Shanghai Centrifugal Machinery Research Institute , Shanghai , China YIN Zhongda Faculty of Heat Treatment of Materials , Harbin Institute of Technology , Harbin 150006 , China

金属学报(英文版)

An approach to study the recrystallization-induced plasticity(RIP)phenomenon in the 18Ni maraging steel under the elastic stress has been made by the analysis of dynamic behaviour at elevated temperatures,the phenomenological analysis of dynamic strain feature curves,the confirmation of phase transformation point and TEM observation of RIP processing itself.

关键词: elastic stress , null , null , null

Rheological Behaviour of Steel ZG15CrMoV and Carbon Steel 35 at High Temperatures

XU Dong AN Geying LI Qingchun Institute of Materials Science and Engineering , Shanghai Jiao Tong University , Shanghai , 200030 , ChinaDept.of Metallic Materials and Technology , Harbin Institute of Technology , Harbin , 150006 , ChinaTo whom correspondence should be ad

材料科学技术（英文）

关键词: steel , null , null

MICROSTRUCTURE AND TENSILE PROPERTIES OF RAPIDLY SOLIDIFIED Al-3.8Li-0.8Mg-0.4Cu-0.13Zr ALLOY PREPARED BY SPRAY DEPOSITION

CUI Chengsong , FAN Hongbo , SHEN Jun , JIANG Zuling , LI Qingchun(Department of Metallic Materials and Technology , Harbin Institute of Technology , Harbin 150001 , China) Manuscript received 26 May 1995

金属学报(英文版)

Al-3.8Li-0.8Mg-0.4Cu-0.13Zr alloy was prepared by a novel spray deposition technique,and its microstructure and tensile properties after various aging treatments have been investigated. The experimental results show that the alloy,under study has very fine equiaxed grains about 5-20μm in diameter and a relative density of(94±3)% on average.Grains in the as-extruded alloy are"brick-like"in morphology,and few oxide particles have been found al the grain boundaries.δ' particles with irregular shape and"δ'-β'"coprecipitates appear in the aged alloy.The coarsening of δ'particles is fast,and the distance between the particles does not widen so obviously as that of IM(ingot-casting method) alloys with increasing aging time.The spray deposited Al-Li alloy.reaches the peak-aged condition in a short time(10 h al 190℃) when the best properties(σb=534 MPa, σ0.2=480 MPa.δ=10%) are obtained.Compared with RSPM(rapid solidification processing method)Al-Li alloy,the ductility of the tested alloy has been obviously.enhanced while a comparable tensile strength is maintained.

关键词: :spray deposition , null , null , null , null

Formation of PFZ and Its Effect in a RSP AI-Li Alloy

Liang ZHEN Yuexian CUI Dezhuang YANG Department of Materials Science , Harbin Institute of Technology , Harbin , 150006 , ChinaShenglong DAI Guifu YU Beijing Institute of Aeronautical Materials , Beijing 100095 , China

材料科学技术（英文）

The formation of precipitation free zone (PFZ) and its effect in a RSP AI-Li alloy has been studied. The results show that PFZ is easy to form when aged at 190℃,but there is no equilibrium phase on grain boundaries.The growth of PFZ in the alloy is different from that in conventional AI-Li alloys, The effect of PFZ is of great importance because of its large volume fraction in the alloy.It offsets the beneficial effect of RSP,and is thought to be an important factor that leads to the poor toughness and low ductility of RSP AI-Li alloy sheet.

关键词: precipitation free zone , null , null , null

IN-SITU OBSERVATION OF THERMAL FATIGUE CRACK GROWTH IN STEEL 3Cr2W8V

LIU Jianhong HE Shiyu YAO Mei Harbin Institute of Technology , Harbin , China lecturer , Depatment of Metallic Materials , Harbin Institute of Technology , Harbin 150006 , China

金属学报(英文版)

The growing process of thermal fatigue cracking,in steel 3Cr2WSV was observed under desk SEM fitted with sell-made minisized device for thermal faligue test.Before the growing of thermal fatigue crack,the main crack tip reveals to blunt firstly,and some holes and uncontinuous microcraeks occur in front of it.The growth is developed by bridging of main crack together with holes and microcracks.

关键词: steel 3Cr2W8V , null , null , null

FRACTURE MECHANISM OF PRE-DEFORMATION-AGED Al-2.73Li ALLOY

SUN Dongli YANG Dezhuang LEI Tingquan CUI Yuexian Harbin Institute of Technology , Harbin , China Lecturer , Department of Metallic Materials and Technology , Harbin Institute of Technology , Harbin 150006 , China

金属学报(英文版)

The fracture mechanism of deformation-aged Al-Li alloy was approached by investigating the influence of prior cold deformation on the precipitation kinetics as well as the behaviours of work hardening and fracture for Al-2.73Li alloy.The experimental results show that the work hardening rate and the strength are increased and the ductility is decreased by prior cold deformation.The decrease in ductility is mainly due to the cell dislocaton substructure distrib- uted inhomogeneously and the hardening of precipitate free zones at grain boundaries caused by prior cold deformation.The failure mode in the alloy is a mixed integranular and transgranular one.The tendency of intergranular fracture is intensified through the deformation-aging.The mechanisms of intergranular failure in the alloy are different under various deformation-aging treatments.

关键词: Al-Li alloy , null , null , null , null

SPREADING PHENOMENON OF Al/Cu CONTACTING REACTION BRAZING

CHEN Dinghua QIAN Yiyu HUANG Jihua Harbin Institute of Technology , Harbin , China Divison of Welding , Harbin Institute of Technology , Harbin.China

金属学报(英文版)

The reactive spread behaviour of Cu particles on the surJace of Al has been studied.The role of oxide film and the .formation mechanism of the joint during Al/Cu contacting reaction brazing have been discussed.

关键词: Al/Cu interface , null , null , null

EFFECT OF TENSION CONDITIONS ON SUPERPLASTIC BEHAVIOUR OF AN Al-Li-Cu-Mg-Zr ALLOY

LIU Qing HUANG Xiaoxu YAO Mei YANG Jinfeng Harbin Institute of Technology , Harbin , China Department of Metals and Technology , Harbin Institute of Technology , Harbin 150006 , China

金属学报(英文版)

A much higher elongation of a warm rolled superplastic Al-Li-Cu-Mg-Zr alloy was made under two-stage strain rate tests comparing with the single ones.During initial stage of deformation a deformation-induced continuous recrystallization which converted a subgrain structure into a recrystallized grain structure by a continuous increase in boundary misorientations had occurred.The higher the strain rate,the faster the continuous recrystallization and the finer the recrystallized grains.The fine recrystallized grain structure formed during the first stage deformation is the essential condition for the material to have high strain rate hardening and strain hardening during the low second stage superplastic deformation.The combination of strain rate hardening and strain hardening is the reason why the higher elongation may be obtained during two-stage superplastic deformation of the alloy.

关键词: Al-Li alloy , null , null , null