偏晶合金液-液相变过程模拟

建立了能描述在弥散相液滴形核、扩散长大、碰撞凝并及两液相空间分离等因素共同作用下，偏晶合金液-液相变过程中组织演变过程的数学模型。将计算的温度场和浓度场与控制凝固组织演变的动力学方程相耦合，模拟研究了单向冷却条件下Al-Pb合金液-液相变过程中的组织演变过程。结果表明，随着冷却的进行，液-液相变区不断由试样底部向试样顶部推进，直至贯穿整个试样。由于在凝固过程中弥散相液滴进行Marangoni迁移和Stokes运动，试样中的某些部位会出现液滴贫化、过饱和度增加和多次形核现象。     

DEVELOPMENT OF NEW THERMO-MECHANICAL SIMULATOR

A new multifunction thermo-mechanical simulator was successfully developed. The accuracy of measurement and control is very high through all digital control. More than twenty tests may bc fulfilled including tension, compression, torsion combination large deformation that meets the study of supersteel,etc.Its performance is introduced in the paper,such as designed ideas, machine structure,man-machinc interface, control system, etc.     

NUMERICAL SIMULATION STUDY ON DEFORMATION UNIFORMITY OF EQUAL CROSS SECTION LATERAL EXTRUSION

Equal cross section lateral extrusion (ECSLE) is an effective method realizing pure shear deformation.The influence of friction factor on the deformation uniformity of ECSLE was investigated with rigid plastic finite element method.The result shows that the non-uniform deformation in extrusion is caused mainly by the friction between workpiece and die.The higher the friction factor is.the more uneven plastic deformation resulted in extruded workpiece.The relation curve of deformation uniformity vs. friction factor was drawn based on the analysis result. The curve can be used as a basis of ECSLE process design.     

THE STRUCTURE CONTROL OF ALUMINUM FOAMS PRODUCED BY POWDER COMPACTED FOAMING PROCESS

A new technique, powder compact foaming process for the production of aluminum foams has been studied in this article. According to this method, the aluminum powder is mixed with a powder foaming agent (Till2). Subsequent to mixing, the powder blend is hot compacted to obtain a dense semi-finished product. Upon heating to temperatures within the range of the melting point, the foaming agent decomposes to evolve gas and the semi-finished product expands into a porous cellular aluminum. Foaming process is the key in this method. Based on experiments, the foaming characteristics were mainly analyzed and discussed. Experiments show that the aluminum-foam with closed pores and a uniform cell structure of high porosity can be obtained using this method by adjusting the foaming parameters: the content of foaming agent and foaming temperature.     

The Adaptive Finite Element Remeshing in Large Deformation of Metal Forming

The adaptive remeshing technique for quadrilateral elements consists of modules the trigger of remeshing, the new mesh generation, adaptive refinement and interpolation of field variables. The new adaptive mesh generation is the key problem. First, a coarse mesh is created by using “loop algorithm“. Subsequent local mesh adaptive refinement is performed based on effective strain. Finally, a typical example of upsetting is given to test efficient of techniques, from which it is verified that the remeshing algorithm developed here exhibits good performance and has high accuracy.     

APPLICATION OF THE UNIFIED STATISTICAL MATERIAL DATABASE FOR DESIGN AND LIFE／RISK ASSESSMENT OF HIGH TEMPERATURE COMPONENTS

Statistical manipulation of material data was conducted for probabilistic life assessment or risk-based design and maintenance for high temperature components of power plants. To obtain the statistical distribution of material properties, dominant parameters affecting material properties are introduced into normalization of statistical variables. Those parameters are hardness, chemical composition, characteristic microstructural features and so on. Creep and fatigue properties are expressed by normalized parameters and the unified statistical distributions are obtained. These probability distribution functions show good coincidence statistically with the field database of steam turbine components. It was concluded that the unified statistical baseline approach is useful for the risk management of components in power plants.     

CALCULATION OF TRANSFORMATION VOLUME FRACTION TO HQ590 HOT ROLLED STRIP STEEL DURING CONTINUOUS COOLING

On the basis of phase transformation kinetics, the transformation of γ→α,P,B have been investigated through considering the effect of deformation. The calculation methods of volume fraction have also been given. Comparing with common method, the simulated results are in more agreement with experiment results.     

面心纯铝单向拉伸的晶体塑性学有限元模拟

基于率相关晶体塑性本构模型,实现了晶体塑性学有限元模拟过程。直接将电子背散射衍射(EBSD)获取的晶粒初始取向输入晶体塑性有限元模型,分别预测了单向拉伸面心1050纯铝过程中的力学响应与织构演化。应力应变响应数值模拟结果与实验结果有较好的一致性,同时也存在一定的偏差。两种多晶模型(Taylor模型和有限单元模型)分别模拟了单向拉伸真应变0.25和0.37时的织构演化。随着真应变的增加,两种丝织构(〈111〉织构和〈100〉织构)变得更加锋锐,模拟结果与EBSD实验测得的织构演化结果有较好的一致性。     

V-EPC制备铸铁基表面复合材料的表面质量和组织

以HT300为基材，以WC颗粒作为增强颗粒，通过V—EPC铸渗工艺制备出较为理想的铁基表面耐磨材料，铸件复合层厚度均匀，厚度可达6mm。WC在复合层中分布较为均匀。在复合过程中，主要是铁液向复合层渗透，铬向母材的渗透也有，但量很少。合金层和母材的结合良好，属于冶金结合，其硬度从复合层到基体先升高后降低，复合层平均硬度比HT300提高了3倍左右。     

NICKEL-BASED ALLOYS IN GE AIRCRAFT TURBINES：PAST,PRESENT ＆ FUTURE

1. Introduction Freedom to travel anywhere in the world, both quickly and inexpensively, defines our modern era. Despite year-to-year variation, the long term demand for travel by airplane continues to grow. Three ma- jor systems comprise the modern airplane: the aircraft structure that encompasses the fuselage, wings, and landing gear; the avionics that enable flight through crowded skies in nearly all weather conditions; and the propulsion system that powers the aircraft. Improvements in mat…