MICROSTRUCTURE OF VERMICULAR GRAPHITE IN CAST IRON

An observation under TEM was carried out of the hetero-particles and stripes inside of thevermicular graphite in cast iron specimens which were prepared by isothermally quenching inice-salt-water.The hetero-particles and stripes,composed of almost pure Fe and a little Si,were found in the regions of the growth direction changing of the vermicular graphite.Manytwins and dislocations were also observed to contribute to changing the growth direction andto providing the growth steps of the graphite respectively.     

CRACK INITIATION AND STEADY PROPAGATION OF ELASTIC-PLASTIC MATERIALS IN PLANE STRESS CONDITION

The crack tip stress-strain fields of the elastic-plastic cracked specimens have been analyzedusing finite element calculations.The crack initiation and steady propagation behaviours havealso been investigated by means of slip line pattern etching technique and mechanical tests.The results show that there are HRR near field and distant field in the crack tip region,andthe later depends on the specimen configuration.The crack initiation behaviour is controlledby a single parameter J.In contrast,the steady crack propagation is affected by the distantstrain field and can not be described by single parameter only.     

水厂铁矿70万t大区微差爆破技术的研究

本文介绍水厂铁矿4年多来进行70万t大区微差爆破技术研究所取得的结果。三次70万t大区微整爆破试验表明,通过采取合理爆破参数和合理微差间隔时间以及应用大孔距爆破技术等途径,可以取得大块率<1%,延米爆破量>70m~3/m以及基本消除根底现象等良好效果。     

含有流动液体的复合材料管道的振动

本文讨论了含有流动液体与复合材料管道的耦合振动问题,其方法是引入位移函数,将文献[1]中关于考虑沿厚度方向的剪切变形及转动惯量的正交各向异性园柱层壳的五个微分方程式转化成一个微分方程式,在此基础上,借助于文献[2]中动水压力公式,研究了无限长度复合材料管道在平均流速为U时的振动问题,作了数值计算,得到了一些有意义的结果。     

Inclusion control of ultra clean ferritic stainless steel

The most important characteristics of the ultra clean ferritic stainless steel is that the carbon,nitrogen and other interstitial elements are very low.The ultra clean ferritic stainless steel has been widely used for household appliances,auto exhaust system,elevator,water treatment system,building roof and other various fields,because of its low cost,pro-environment,excellent properties.They can replace some traditional austenitic stainless steel.such 304 and 316L.The addition of titanium to liquid steel has become common for stabilizing nitrogen and carbon in steel.Titanium reacts with nitrogen,carbon,and oxygen to form titanium nitride,carbide, carbonitride and oxide.These inclusions may have a deleterious effect on the properties such as toughness, ductility,weldability and corrosion.In addition,the inclusions can also agglomerate and cause surface quality problem of the slab and clogging of the submerged entry nozzle during continuous casting process. The formation rules of inclusions in ultra clean ferritic stainless steel were investigated by the thermodynamic calculation,and methods of controlling inclusions were put forward to improve the quality of product.The composition,type,amount,size and distribution of the inclusions in the slab are investigated by optical microscope and scanning electron microscope.The results can be concluded as follows.（1） In the slab,the main original inclusions,with size of larger than 2μm,are Al₂O₃,TiN or Ti（CN） and complex TiN or Ti（CN） inclusion with core of MgO,MgO-Al₂O₃ and Ti₂o₃,which will not affect the performance of the steel if they are in diffusing distribution.The size of these inclusions are less than 10μm except some Al₂O₃ inclusions in size of 10-40μm.（2） Foreign inclusions are Ti₂O₃-Al₂O₃-MgO-SiO₂ in size above 50μm covered by TiN or Ti （CN）.Although these inclusions are few,they do harm to the surface quality of stainless steel.It is able to reduce the risk of forming this kind of inclusion by aluminium deoxidation with increasing Al content to restrain the formation of Ti₂O₃.（3 ） TiN or Ti（CN） is easy to precipitate on inclusions such as MgO,MgO-Al₂O₃ and Ti₂O₃,except Al₂O₃.Controlling the content of[Ti]and[N]and the formation of the oxides can be used to control the precipitation of TiN or Ti（CN）.     

Analysis of the change of roll thermal crown in 1750 mm hot strip mill

Studied the distributing of roll temperature and the change rule of thermal crown in 1 750 hot strip mill,the result of the test showed that the change of roll thermal crown was affected by the condition of roll cooling and equipmentthe roll thermal crown was obviously improved after altering the pipe and water nib of cooling equipment.From the rule of roll thermal crown changing with the number of strip rolling know that the thermal crown of work roll of Standi is the largest,and Stand 6 is the smallest...     

提高15000m~3/h空分设备气体产量的实践

介绍15000 m3/h空分设备的实际运行状况,分析提高空分设备氧气和氮气产量的可行性,详细阐述提高氧气和氮气产量的分析、摸索过程以及最终的实施方案和具体运行参数。     

NUMERICAL SIMULATION OF BUBBLE FLOW INTERACTIONS

Bubble flow interaction can be important in many practical engineering applications. For instance, cavitation is a problem of interaction between nuclei and local pressure field variations including turbulent oscillations and large scale pressure variations. Various types of behaviours fundamentally depend on the relative sizes of the nuclei and the length scales of the pressure variations as well as the relative importance of bubble natural periods of oscillation and the characteristic time of the field pressure variations. Similarly, bubbles can significantly affect the performance of lifting devices or propulsors. We present here some fundamental numerical studies of bubble dynamics and deformation, then a practical method using a multi-bubble Surface Averaged Pressure (DF-Multi-SAP©) to simulate cavitation inception and scaling, and connect this with more precise 3-D simulations. This same method is then extended to the study of two-way coupling between a viscous compressible flow and a bubble population in the flow field.     

ACOUSTIC MEASUREMENTS BUBBLES IN BIOLOGICAL TIESSURE

An acoustic based instrument,the ABS Acoustic Bubble Spectrometer(R)(C)(ABS),was investigated for the detection and quantification of bubbles in biological media.These include viscoelastic media(blood),materials of varying density(bone in tissue),non-homogenous distribution of bubbles(intravenous bubbly flow),and bubbles migrating in tissue(decompression sickness,DCS).The performance of the ABS was demonstrated in a series of laboratory experiments.Validation of the code was performed using a viscoelastic polymer solution,Polyox,in which the bubble size distribution and void fraction were determined by ABS measurements and with image analysis of high speed videos.These tests showed that the accuracy of the ABS was not significantly affected by viscoelasticity for bubbles smaller than 200 microns.The ABS detection and measurement of non-homogenous bubble distributions was demonstrated using a bubbly flow through a simulated vein surrounded by tissue.The scatter of acoustic signals due to bones in the acoustic pathway was also investigated.These in-vitro experiments were done using meat(beef)as a tissue simulant.Decompression experiments were done using beef meat which was held underwater at high pressure(9.9 atm)then rapidly decompressed.Bubble size distributions and void fraction calculations in these experiments were then validated using image analysis of high speed video.In addition,preliminary experiments were performed with the US Navy Medical Research Center,demonstrating the utility of the modified ABS system in detecting the evolution of bubbles in swine undergoing decompression sickness(DCS).These results indicate that the ABS may be used to detect and quantify the evolution of bubbles in-vivo and aid in the monitoring of DCS.