我国轧钢生产技术的进步和展望--依靠技术进步,提高钢材的市场竞争力

回顾了近年来我国钢材品种结构调整，轧钢装备水平，新产品开发和轧钢技术理论研究所取得的主要进步，指出了我国轧钢生产技术仍存在的问题，为提升我国整个轧钢行业的核心竞争力，提出了今后两年我国轧钢生产技术进步的主要任务。     

45钢棒材冷拔断裂原因分析

采用化学成分分、金相分析、断口扫描电镜及电子探针分析等手段，对45钢棒材冷拔断 裂的原因进行了分析研究。结果表明：钢中Cu元素含量偏高；轧钢加热期间钢坯 表面氧化严重造成钢材表面附近区域Cu元素富集，冷拔过程 中钢材表面附近的Cu富集区域首先开裂，导致钢材冷拔断裂。     

我国轧钢生产技术的进步和展望——依靠技术进步,提高钢材的市场竞争力

回顾了近年来我国钢材品种结构调整、轧钢装备水平、新产品开发和轧钢技术理论研究所取得的主要进步;指出了我国轧钢生产技术仍存在的问题;为提升我国整个轧钢行业的核心竞争力,提出了今后两年我国轧钢生产技术进步的主要任务。     

加快降低轧辊消耗措施的探讨

1 前言轧钢生产中轧辊的消耗,不仅与钢材产品结构、轧钢工艺技术和轧钢设备状况有关,还与轧辊制造技术、轧辊材料的开发应用以及轧辊管理水平有关。它直接影响着轧钢生产作业率、生产成本和企业的经济效益。     

分析市场 调整结构 把握投资——在1997年全国轧钢工作会议上的讲话

就轧钢工业面临的形势及各类钢材发展的市场前景进行了分析，阐述了轧钢厂（尤其是棒线材厂）合理的经济规模、连铸坯尺寸的确定原则；同时指出，在实现流程优化、系统优化过程中要高度重视国产化问题，并做好参数、规模、投资的优化工作。     

21世世轧钢技术的发展

展望21世纪，钢铁工业将面临更加激烈的竞争，但轧钢仍是钢材成形的支柱技术，对世界经济发展和社会文明起基础性支持作用，21世纪轧钢技术进步将集中于生产工艺流程的连续化、紧凑化，过程控制将实现轧材性能的高品质化、品种规格多样化及控制和管理的计算机化和信息化。     

优化工艺结构 促进节能降耗 实现优质高效——在1998年全国炼钢轧钢工作会议上的讲话

在总结１９９７年炼钢、轧钢生产取得的成绩和存在问题的基础上,提出了炼钢、轧钢结构调整、优化衔接,即实现整体结构优化的基本思路,指出必须大力发展连铸坯热送热装技术及推进高性能钢材品种的开发,并具体提出了１９９８年炼钢、轧钢生产的主要目标和重点任务。     

我国轧机的装备水平、技术改造和引进

解放前,我国的钢铁工业非常落后,轧钢装备和生产技术更为落后。1949年解放前夕,全国只有寥寥几套轧钢机,钢材产量只有14万吨。解放后,我国轧钢生产在一穷二白的基础上有了迅速发展。特别是经过了三年恢复时期,     

行业信息

中国金属学会第六届轧钢学术大会召开中国金属学会第六届全国轧钢学术大会于１９９６年１０月２１日至２４日在武汉市召开。这次大会由中国金属学会轧钢学会和冶金部科技司共同主办。会议主要研讨了国内外轧钢生产技术的发展动向和趋势；交流了我国近年来轧钢生产、科技进步的状况和经验；在社会主义市场经济条件下，轧钢企业所面临的形势与对策；以及２０１０年我国轧钢技术的发展战略。各钢铁企业、设计和研究院所、大专院校以及中国金属学会、冶金部有关司局领导等共计１４９个单位，２７４名代表应邀参加了大会。大会由中国金属学会轧钢…     

传播新技术 促进轧钢事业的发展

《轧钢》杂志开始正式发行,我谨向《轧钢》杂志的编辑人员、工作人员和撰稿人表示祝贺。衡量冶金工业规模的是钢产量,冶炼是为轧钢提供原料,而轧钢是钢铁企业生产的最后工序——向社会提供钢材。随着国民经济的发展和建设规模的不断扩大,近年来虽然钢的产量每年增长300×10~4t左右,但所     

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).     

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.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

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.