四边形钢塔结构动力反应研究

本文采用了不同的力学模型及计算方法对四边形钢塔结构的动力特性进行了分析:(1)杆系-层间模型,振型分解法计算;(2)空间杆系模型,振型分解法计算;(3)杆系-层间模型,直接动力法计算。为了验证计算结果的可靠性,又用两种方法进行了检验;(1)激振法,(2)脉动法,其中又分为光线记录,人工分析数据和磁带记录,数据处理机分析数据。文中并对三种计算方法和二种试验方法进行了比较,供对类似结构进行计算或试验时参考。     

Rheological properties of wheat flour and quality characteristics of pan bread as modified by partial additions of wheat bran or whole grain wheat flour

The use of bran and whole grain flour changes dough rheology and causes difficulties in manufacturing bakery products. The aim of this study was to analyse the influence of substituting refined wheat flour (WF) by wheat bran (WB; 5%, 10%, 20%, 30% and 40%) or whole grain wheat flour (WGWF; 10%, 20%, 30%, 40% and 50%) on dough rheological properties and pan bread quality characteristics. The addition of WB and WGWF increased water absorption and resistance to extension and decreased stability, extensibility and peak viscosity. Effects with WB were more pronounced. The presence of WB or WGWF increased crumb moisture content, firmness and hardness and decreased specific volume of pan bread. It is important to set new farinographic and extensographic standards when using WB and WGWF, allowing for a correct correlation between rheology and quality characteristics of bakery products, as the same standards used for WF are not valid.     

Analysis of sensitization phenomenon in friction stir welded 304 stainless steel

This study evaluates the degree of sensitization (DOS) of 304 stainless steel joined by friction stir welding (FSW). Single-loop electrochemical potentiokinetic reactivation tests were performed using a 0.5 mol/L H₂SO₄ + 0.01 mol/L KSCN solution. Sensitization was promoted by exposition of the stainless steel at temperatures between 400°C and 850°C. The microstructure was characterized using optical microscopy to identify the weld zone and the base metal. The samples treated at 550°C showed the most severe intergranular corrosion. The DOS was lower in the weld zone than in the base metal after heat treatments. This reduction in the DOS for the weld zone indicates that FSW is a beneficial process in joining stainless steel.     

美国低碳炼铁新技术进展及应用前景分析

美国开发的低碳炼铁新技术主要有氢气闪速熔炼法和熔融氧化物电解法.介绍了氢气闪速熔炼法和熔融氧化物电解法的研究进展,对其应用前景进行了分析.     

Application and practice of ceramic fiber block technology in industrial furnaces

Ceramic fiber,a kind of furnace lining material,is widely utilized in industrial furnaces.Fiber blocks can be made into various shapes.They have advantages of low thermal conductivity,low density and light weight for the development of industrial furnaces.This paper,taking a continuous annealing furnace as an example,describes the application of ceramic fiber blocks in the furnace and the installation methods.The temperatures of the furnace wall with different linings are analyzed.In the furnace design or the renovation of the existing furnaces,lining with ceramic fiber blocks is the preferred solution.     

Gas-particle partitioning of polychlorinated dibenzo-p-dioxins and dibenzofurans in the sintering process

The distribution of seventeen gaseous and particle-bound 2,3,7,8-substituted chlorinated PCDD/Fs in the flue gas of different windboxes of the sintering machine was analyzed.The influence of temperature change on the PCDD/Fs emission from the sintering process and the formation mechanism of PCDD/Fs were discussed.The result has shown that among the seventeen gaseous and particle-bound PCDD/Fs in the flue gas of different windboxes,furans occupied the major place.The proportion of the gaseous PCDD/Fs in most windboxes is from 40% to 60%.The change tendencies of the concentration of both the gaseous and particle-bound PCDD/Fs were similar,with a higher level at the end of the sintering bed.The PCDD/Fs concentration’s change tendency in the windbox was very consistent with the change of temperature of the flue gas in the windboxes.More than 60% PCDD/Fs of the total PCDD/Fs emission amount was emitted at the end of the sintering bed.Only this part of the waste gas accounted for 12% of the total waste gas volume.     

Numerical simulation of tube profile growth during spray forming process

Spray forming is a new type of metal material forming process,which can produce metal blanks such as billet,tube,plate etc.A mathematical model has been developed to forecast the shape evolution of tube billets during the spray forming process.The atomizer mass flux as,radial distribution coefficient bs,draw velocity and diameter of mandrel were considered in this model and the influence of different parameters such as metal flowrate,draw velocity of mandrel,diameter of mandrel on the tube’s shape change were simulated and analyzed in this paper.The simulation results obtained from this model can be provided to engineers as reference.     

Status and development of mineral wool made from molten blast furnace slag

This study describes the characteristics of mineral wool and its applications,and also introduces the traditional process of mineral wool made from molten blast furnace(BF) slag.Compared with high energy consumption of the traditional process,the production of mineral wool by using molten BF slag will be able to take full advantage of the sensible heat of molten slag,and also reduce production costs.However,there are also further issues to resolve such as how to obtain the required amount of molten BF slag and how to make it homogeneous.Based on the physical and chemical properties of the molten BF slag,the investigation into the relationship between temperature and viscosity under different acidity coefficients of the slag and silicon mixture was conducted.Combined with the crystallization and phase diagram of slag wool,its heat resistance,water resistance,durability and corrosion resistance were analyzed.Finally,trends of the technology development are proposed.     

Research on the trajectory of non-metal inclusions with the flow in the mold during the solidification of continuous casting slabs

By means of the numerical simulation method,the mathematical model of inclusions movement in the mold is established under the condition of austenitic and ferritic stainless steel slab production.According to the simulation results,the main zones for inclusion particles accumulation were found and many factors that affected floating-up probability of inclusion particles were identified.These factors include the inclusion particle size,the casting speed and the slab width,etc.It is believed that the inclusion particle size is the key one among these factors.     

Microstructure and micro-hardness of the Inconel 718 superalloy coating prepared by cold gas dynamic spraying

Inconel 718 superalloy coating was prepared on a martensitic steel substrate by cold gas dynamic spraying (CGDS).Microstructure and micro-hardness of the coating were characterized by means of scanning electronic microscope (SEM),energy dispersive spectrometer (EDS),and micro-hardness and nano-indentation tests.The results have indicated that the coating’s thickness can reach more than 300 μm,and there exists a good interfacial cohesion between the coating and the substrate.The quantity and size of the defects at the bottom,middle and top areas increase gradually.There is no significant change to the original microstructure of the Inconel 718 superalloy particle after the process of CGDS;and an obvious torsional deformation on the particle’s profile is produced while little deformation at the center part occurs.The micro-hardness of the coating at the bottom,middle and top areas decreases in turn.Compared with the bottom area,the micro-hardness of the middle and top areas decreases by about 10% and 21%,respectively.The nano-hardness of the coating is much lower than the original particle,which decreases by about 13.5% at the bottom area and 28% at the top area,respectively.The distribution of micro-defects is an important factor to the micro-hardness of the coating.