材料期刊网

NUMERICAL ANALYSIS OF THREE-DIMENSIONAL FLUID FLOW AND HEAT TRANSFER IN TIG WELD POOL WITH FULL PENETRATION

WU Chuansong , CAO Zhenning , WU Lin Harbin Institute of Technology , Harbin , China

金属学报(英文版)

A model is established to analyze three-dimensional fluid flow and heat transfer in TICweld pools with full penetration.It considers the deformation of the molten pool surfaceat the condition of full penetrated workpieees,takes the are pressure as the drivingforce of the pool surface deformation,and determines the surface configuration of weldpool based on the dynamic balance of arc pressure,pool gravity and surface tension atdeformed weld pool surface. The SIMPLER algorithm is used to calculate the fluid flowfield and temperature distribution in TIG weld pools of stainless steel workpieces.TIGwelding experiments are made to verify the validity of the model.It shows the calculatedresults by the model are in good agreement with experimental measurements. professor,Dept of Welding Engineering,Harbin Institute of Technology,Harbin 150006,China

关键词: KEY WORDS TIG weld pool , null , null , null , null

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

MODIFICATION EFFECT OF Sr ON Al-Si ALLOYS

LIU Qiyang LI Qingchun ZHANG Jiren Harbin Institute of Technology , Harbin , China LIU Qiyang , Division of Foundry , Department of Mechanical Engineering No.2 , South China University of Technology , Guangzhou , China

金属学报(英文版)

By inserting the single crystal silicon seeds into Sr modified Al-22wt-% Si alloy melts,the fact that nucleation and growth of Si-phase are affected by Sr addition has been confirmed.It is suggested that this effect is caused by the adsorption of Sr on{111}_(si),and the modification of eutectic structure results from the variation of leading phase in the eutectic from Si to α-Al.

关键词: Al-Si alloy , null , null

CHARACTERISTIC TRANSITION TEMPERATURE OF BRITTLENESS OF LOW CARBON STEEL

HUANG Zheng Institute of Physics , Academia Sinica , Beijing , ChinaYAO Mei Harbin Institute of Technology , Harbin , China Institute of Physics , Academia Sinica , Beijing 100080 , China

金属学报(英文版)

On the basis of analysis of low carbon steel fracture macro-features and micro-processes at low temperature,the definition was given of the characteristic transition temperature of brittleness,T_(pm),and its physical meaning was expounded.Discussion was carried out of phys- ical characteristic of variation at T_(pm) in respect of the fracture toughness and property of crack arrest.In addition,research was made on the application of T_(pm),which can give infor- mation about the transition of the fracture toughness,the property of crack arrest and critical crack size,to estimation the brittleness of low carbon steel at low temperatures.

关键词: low carbon steel , null , 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

CRITICAL NOTCH(CRACK)SIZE AS A CHARACTERISTIC PARAMETER EVALUATING CRYOGENIC BRITTLENESS IN LOW CARBON STEEL

LI Daoming YAO Mei Harbin Institute of Technology , Harbin , China Box 617 , Harbin Institute of Technology , Harbin , China

金属学报(英文版)

The effect of notch depth on the cryogenic fracture behavior has been studied using a low car- bon steel.An analysis was made for the fracture features at T_c~*(cryogenic brittleness-char- acteristic temperature)at which the facture load reaehes a valley value.Furthermore,accord- ing to the experimental results and engineering design practice,a concept of critical notch (crack)'size for cryogenic brittleness,a_c,as well as its limit value a_c~*,was put forward and recommended to be a basic characteristic parameter for controlling the brittleness. Mathematical derivation was carried out to give the expression of a_c and a_c~*,the reliability of which was verified by the modeling tests under both static and cyclic loading conditions.

关键词: low carbon steel , null , null

MATHEMATICAL MODELS OF NITROGEN CONCENTRATION PROFILE OF ION NITRIDED LAYERS AND COMPUTER SIMULATION

XIA Lifang YAN Mufu Harbin Institute of Technology , Harbin , China Laboratory of Metal Materials and Heat treatment , Harbin Institute of Technology , Harbin , China

金属学报(英文版)

The mathematical models of the kinetics of the layer growth at different ion nitriding condi- tions of armco iron.steels 45,40Cr,42CrMo and 38CrMoAl have been established.Based on these models the expression of nitrogen concentration profile of ion nitrided layers have been deduced with profile simulating method.They are C_=C_(min)~+(P_4)/(ξ_1-x)+(P_5)/(ξ_(10)~2)(ξ_1-x)~2 C_(γ′)=C_(min)~(γ′)+(P_1)/(ξ_(21))(ξ_2-x)+(P_2)/(ξ_(21)~2)(ξ_2-x)~2 C_α=C_(min)~α+(C_(33))/(C_(33))/(ξ_(32))(ξ_3-x)~3 Using these models,the kinetics of layer growth and the nitrogen concentration profile of ion nitrided layers were sinulated on Apple-Ⅱ computer.Results show that the simulated curves coincide quite well with the experimental data.

关键词: computer simulation , null , null

MICROSTRUCTURES AND PROPERTIES OF SiC_w/AL COMPOSITES

GUO Shuqi HAN Guihuan YAO Zhongkai Harbin Institute of Technologh , Harbin , China YAO Zhongkai Dept.of Metals and Technology , Harbin Institute of Technology , Harbin , China

金属学报(英文版)

This paper presents an investigation on the microstructures and properties of the 17v.-% SiCw/Al-12Si composites.TEM observations and EDAX analysis revealed that Al diffuses into the SiC whiskers and that dislocations exist at the whisker/matrix interfaces. Tensile test results showed that the isothermal exposure and thermal cycle at both 573K and 733 K caused the UTS reduction of the composites,and the reduction in UTS due to thermal exposure at 733 K was much more significant than that due to thermal cycle at the same tem- perature.The SiC_W/Al-12Si composites were also found to have exellent wear resistance, which does not seem to vary much with the volume content of whiskers in the ronge of 11— 17%.

关键词: composites , null , null , null