大双冲天炉在我厂的应用

将3吨/小时三排冷风冲天炉改为5吨/小时大双冲天炉,讨论了其结构参数的合理选择和采用双风箱与单风箱的区别;以及使用劣焦炭也能获得较好熔炼效果。     

国内“外热式”热风冲天炉应用情况简介

1概述预热送风是强化冲天炉熔炼的有效措施之一，热风能强化底焦燃烧，提高熔炼效果。当风温超过3500℃，对提高铁水温度、改善铁水质量、降低焦耗和提高熔化率等均有显著效果，冲天炉的热效率随热风温度的提高而提高，国外冷风冲天炉的热效率一般为32．4％，当风温为600℃时，热效率可提高到60％，几乎是冷风冲天炉的2倍。冷热风冲天炉熔炼效果对比实例见表：注：冷风时焦耗为14％，送风强度为100m3／min，出铁温度为1400℃热风对冲天炉熔炼的主要作用是：①送风湿度提高，将使空气中自由氧更为活跃，从而增加了氧和碳的反应速度，强化了底…     

热风与冷风冲天炉－工频炉双联熔炼效果对比

对比了热风与冷风冲天炉－工频炉双联熔炼效果，认为采用热风冲天炉－工频炉双联熔炼可以低成本地获得高强度低应力灰铸铁．     

热风与冷风冲天炉—工频炉双联熔炼效果对比

对比了热风与冷风冲天炉－工频炉双联熔炼效果，认为采用热风冲天炉－工频炉双联熔炼可以低成本地获得高强度低应力灰铸铁。     

湖北省三十九座冲天炉熔炼水平的分析

用方差分析法分析了参加湖北省首届冲天炉熔炼技术质量竞赛的39座冲天炉的铁水温度、铁水质量、热效率、送风电耗和炉衬寿命五个方面的十六项技术经济指标,定量地评价了两排短间距卡腰炉、多排小风口冲天炉,三排风口曲线炉膛冲天炉和倒大双冲天炉的熔炼效果,由于原材料和操作工艺参数的作用大于炉型的作用,建议重视冲天炉熔炼过程操作工艺参数的定量化和我国标准冲天炉的研究     

炼钢渣铁在冲天炉中的熔炼

采用外热风冲天炉熔炼炼钢渣铁可获得高碳低硫生铁,实现炼钢渣铁的高效益回收利用.从冲天炉设备、炉料、熔炼工艺等方面分析了熔炼的技术条件;介绍了冲天炉的结构特点、炉料的预处理、熔炼工艺参数及熔炼操作.     

富氧送风在冷风冲天炉的应用

介绍了冷风冲天炉富氧的原理及工艺设计,对比了冷风冲天炉富氧前后的经济效益,采用富氧送风工艺后,改变了冷风冲天炉在南方夏秋季节的运行效益.根据生产经验,提出了富氧强化的关键控制点及冲天炉在铸造行业中的存在价值,得出以下结论:(1)富氧送风工艺可以降低冲天炉的能源消耗;(2)不会影响冲天炉熔炼的铁液质量;(3)可以降低冲天...     

冲天炉可调风口的设计与应用

研制出一种可调风口，应用在双屑化铁炉和冲天炉上，能使熔炼操作方便快捷，提高熔炼效果。可调风口为冲天炉熔炼操作的精细化创造了1个有利条件。     

3 t/h两排大间距二次送风冷风冲天炉的熔炼控制

针对两排大间距二次送风冷风冲天炉中有关主风口和二次风口在参数选择以及该炉型在实际使用中的生产控制问题,以设计使用的3 t/h两排大间距二次送风冷风冲天炉为依据,对使用中的主要操作参数和生产过程控制进行了较详细的论述,给出了部分实际测试数据,能够很好地为企业操作同类炉型提供借鉴.     

冲天炉熔炼节能减排的途径

对冲天炉熔炼过程中的熔炼环境、炉况状态、动力消耗等对能量损失的影响以及烟尘、噪声等污染物排放对环境的影响进行了分析;介绍了冲天炉附属设备、原材料及燃料选用、熔炼工艺及操作过程等方面的节能减排途径;指出适当配置装备、优化操作及合理选料和组织生产是实现冲天炉熔炼节能减排的基本措施。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.