Longitudinal surface cracks on continuous casting slabs of P and Cu containing container steel

The fact that the amount of the mold flux components differs at differentlocations on the cracking surface indicates that the longitudinal surface cracks are initiallyformed in the mold and are enlarged in the secondary cooling zone. Based on the hot ductilitymeasurement of two typical container used steels, it is known that the steels are in severeembrittlement state in the temperature range of 825-775 deg C. By means of increasing Cr/Ni platingthickness on the upper part of the mold, reducing mold heat flux, adopting new secondary coolingpattern, etc., the occurrence of the surface longitudinal cracks on the steel CC (continuouscasting) slabs has been significantly reduced.

Investigation on the temperature distribution and strength of flat steel ribbon wound cryogenic high-pressure vessel

By analyzing heat transfer on the wall of fiat steel ribbon wound vessel （FSRWV）, a numerical model of temperature distribution on the entire wall （including inner core wall, flat steel ribbons, outside cylinder of jacket and insulating layer） was established by the authors. With the model, the temperature distribution and the length change in the vessel walls and flat steel ribbons in low temperature are calculated and analyzed. The results show that the flat steel ribbon wound cryogenic high-pressure vessel is simpler in structure, safer and easier to manufacture than those of conventional ones.

Advances in the research of nitrogen containing stainless steels

The current status of nitrogen containing stainless steels at home and aboard has been introduced. The function and existing forms of nitrogen in the stainless steels, influence of nitrogen on mechanical properties and anti-corrosion properties as well as the application of nitrogen containing cast stainless steels were discussed in this paper. It is clear that nitrogen will be a potential and important alloying element in stainless steels. And Argon Oxygen Decarbonization (AOD) refining can provide an advanced manufacture process for nitrogen containing stainless steels with ultra-low- carbon and high cleanliness.

Corrosion of two kinds of cast steels containing chromium in hot concentrated alkaline

A typical hot concentrated alkaline corrosion environment exists in alumina metallurgical industry, so that steel materials with outstanding alkaline corrosion resistance are strongly demanded for its processing equipment. In this paper, the corrosion resistance of two kinds of martensitic cast steels containing chromium in static 303g/L NaOH alkaline solution at 85℃ was studied through polarization and potential-time curves, corrosion weight loss and corrosion morphology analysis. Experimental results showed that protection effect by passive film of cast steel containing Cr was temporary. The low carbon steel without Cr content also exhibited chemical passivity in the same solution. The corrosion mode of the tested Cr-containing cast steel was composed of active dissolving corrosion and caustic embrittlement cracking. Dissolving corrosion was the primary mechanism for the induced weight loss, while severe caustic embrittlement cracking was secondary. With the increase of chromium content in the cast steel, the tendency of the caustic embrittlement cracking decreased, while the active dissolving corrosion increased.

Stress Corrosion Cracking of Nitrogen-containing Stainless Steel 316LN in High Temperature Water Environments

Stress corrosion cracking （SCC） of stainless steels and Ni-based alloys in high temperature water coolant is one of the key problems affecting the safe operation of nuclear power plants （NPPs）. The nitrogen-added stainless steel is a kind of possible candidate materials for mitigating SCC since reducing the carbon content and adding nitrogen to offset the loss in strength caused by the decrease in carbon content can mitigate the problem of sensitization. However, the reports of SCC of nitrogen-added stainless steels in high temperature water are few available. The effects of applied potential and sensitization treatment on the SCC of a newly developed nitrogen-containing stainless steel （SS） 316LN in high temperature water doped with chloride at 250 ℃ were studied by using slow strain rate tests （SSRTs）. The SSRT results are compared with our data previously published for 316 SS without nitrogen and 304NG SS with nitrogen, and the possible mechanism affecting the SCC behaviors of the studied steels is also discussed based on SSRT and microstucture analysis results. The susceptibility to cracking of 316LN SS normally increases with increasing potential. The susceptibility to SCC of 316LN SS was less than that of 316 SS and 304NG SS. Sensitization treatment at 700℃ for 30 h showed little effect on the S CC of 316LN S S and significant effect on the S CC of 316 S S. The predominant cracking mode for the 316LN S S in both annealed state and the state after the sensitization treatment was transgranular. The presented conditions of mitigating stress corrosion cracking are some useful information for the safe use of 316LN SS in NPPs.

Oxidation Behaviour of Laser Remelted Cr-containing Steels

Laser surface remelting of steels with different Cr contents has been performed by using a CO_2 laser. The results of oxidation tests showed that the effects of laser remelting on the oxidation resistance of Cr-containing steels have close relation to the Cr contents and microstructures of the steels. The re- sistance to high temperature oxidation of 18-8 and HK40 at 1273 K can be obviously improved by laser remelting, whereas laser remelting showed little effect on the oxidation resistance of Fe-6Cr and Cr30 at 1173-1273 K.

Rheology of Steel Fibre Containing Alumina-Magnesia-Extruded Graphite Pellets Self-Flowing Castables

The influences of adding steel fibres of different lengths up to 3 volume percentages, on the rheological behaviour of an alumina-magnesia-extruded graphite pellet containing castables have been studied using a rheometer. Free-flow measurements have shown that the flow is severely affected by increasing the length of steel fibres. The calculated values of rheological constants indicate that 19 mm and 25 mm fibre up to 2 volume percentage is permitted while one volume percentage of 50 mm fibres severely degrades the rheology of the castable.

Effect of water quenching processing parameters on the mechanical properties of a cold-rolled C-Mn-containing steel sheet

Cold-rolled advanced high-strength steel sheets have become the material of choice for the automotive industry because of their unique attributes of high strength and balanced mechanical properties.High-hydrogen gas jet cooling and water quenching are the most commonly used ultrafast cooling technologies for producing martensite-containing high-strength steel sheets.The water quenching technology ensures the fastest industrial cooling rate of 1 000 K/s;therefore,it has the highest potential with respect to saving alloys.In this study,the water quenching of a C-Mn-containing steel sheet is simulated during continuous annealing to investigate the effect of water quenching and tempering parameters on its mechanical properties.The results reveal that at low quenching temperatures,the strength of the steel sheet decreases as the soaking temperature increases.However,at high quenching temperatures,a high soaking temperature corresponds to increased strength after quenching,regardless of whether the material was austenitized in the single austenite zone or the inter-critical zone.Therefore,a high quenching temperature always results in a high strength and a high yield ratio after quenching.Low-temperature overaging(tempering) considerably influences the yield strength and yield ratio,and the extent of this influence is correlated with the soaking temperature.

Corner crack mechanism of boron-containing LCAK steel slabs

At Baoshan Iron ＆ Steel Co., Ltd., comer cracks of boron containing LCAK steel slabs had caused remarkable quality loss and mass flow disorder. With the help of fractography and thermodynamics analysis, the embrittlement mechanism of this steel grade was studied and the results are as follows： 1 The transformation from 3＇ to a starts at the austenite grain boundaries and a layer of thin ferrite film gradually forms around the austenite grains. Strain concentration will preferentially start inside the ferrite phase when the stress accumulates to a certain level. 2 The coarse BN particles acceleratedly precipitated at the γ/α interfaces further deteriorate the ductility of the ferrite film, and brittleness results in strain concentration and microvoid coalescence inside the ferrite film. Therefore the austenite grain boundaries are prone to intergranular failure. 3 The stoichiometry among Al, N and B is a very important factor influencing the hot ductility of this steel grade. By controling the B-to-N atomic ratio to above 1, all N can be fixed by B instead of A1. Thus coarsegrained steel is available and fewer grain boundaries and higher ductility can reduce the risk of comer cracks. （4） By adjusting the B-to-N atomic ratio,Baoshan Iron ＆ Steel Co.,Ltd. successfully reduced the number of cracks to nearly one tenth of that in the past and the hot tensile tests confirmed remarkable improvement in the hot ductility of this steel.

Effects of Al and Ni on copper-rich phases in the scale/steel interface after high-temperature oxidation of copper-containing steel

A study was conducted on the formation of a Cu-rich phase at the scale/steel interface of Cu-containing steel by high-temperature oxidation with varying amounts of A1 and Ni. Both A1 and Ni were found to help decrease the amount of the Cu-rich phase at the interface. Analysis of the effects by these elements was conducted in terms of the melting point of the Cu-rich phase, the solid solubility of Cu in austenite, the rate of oxidation, and the amount of Cu-rich phase occlusions in scales. Because of selective oxidation,in which A1 and Ni are oxidized more and less preferentially than Fe, respectively, A1 was weakly concentrated at the interface whereas Ni was more heavily concentrated in it. Thus, A1 exerted no effect on the melting point of the Cu-rich phase, whereas Ni raised its melting point. A1, which was applied at contents of less than 2.0%, decreased the solubility of Cu in austenite but this effect weakened at the interface during oxidation. By contrast,Ni increased the solubility of Cu, and this effect was strengthened with oxidation. Both A1 and Ni promoted internal oxidation and the formation of occlusions.

Effects of oxygen content on the oxidation process of Si-containing steel during anisothermal heating

The oxidizing behavior of Si-containing steel was investigated in an O2 and N2 binary-component gas with oxygen contents ranging between 0.5 vol% and 4.0 vol% under anisothermal-oxidation conditions. A simultaneous thermal analyzer was employed to simulate the heating process of Si-containing steel in industrial reheating furnaces. The oxidation gas mixtures were introduced from the commencement of heating. The results show that the oxidizing rate remains constant in the isothermal holding process at high temperatures; therefore, the mass change versus time presents a linear law. A linear relation also exists between the oxidizing rate and the oxygen content. Using the linear regression equation, the oxidation rate at different oxygen contents can be predicted. In addition, the relationship between the total mass gain and the oxygen content is linear; thus, the total mass gain at oxygen contents between 0.5 vol%–4.0 vol% can be determined. These results enrich the theoretical studies of the oxidation process in Si-containing steels.

NAPA STEEL在大型集装箱船结构设计中的应用

目前众多三维设计软件在国内船舶生产设计中的应用已相当成熟,而在基本设计和详细设计中的应用尚处于摸索和发展阶段。NAPA STEEL是芬兰NAPA公司开发的船舶设计软件包中的结构设计模块。文章利用NAPA STEEL对2艘万箱级集装箱船进行结构辅助设计,在基本设计和详细设计阶段中参与完成了二维出图、质量统计、船级社软件接口及有限元输出的任务,探索了利用NAPA STEEL软件对大型集装箱船进行参数化建模以完成结构辅助设计的方法,并总结出一些宝贵的经验。

Study on Interaction between Lanthanum and Phosphor in Purity Steel

Using SEM and EDS some particles containing La and P were discovered in low oxygen and sulfur purity steel with lanthanum. In these particles low melting point elements such as As and Sb also were detected. According to the result of simulative calculation of segregation, it is shown that La and P enrich so strongly in the process of solidification that their concentrations can satisfy thermodynamic condition to forme LaP compound or meet the requirements to forme eutectic phase in the last stage of solidification. Therefore, the particles are concluded as LaP compound or eutectics, which exist on grain boundary mainly.

Numerical Simulations of the Performance of Steel Guardrails Under Vehicle Impact

Road side barriers are constructed to protect passengers and contain vehicles when a vehicle crashes into a barrier. In general, full-scale crash testing needs to be carried out if a geometrically and structurally equivalent barrier has not previously been proven to meet the requirements of containing the vehicle and dissipating sufficient impact energy for passenger protection. As full-scale crash testing is very expensive, the number of data that can be measured in a test is usually limited, and it may not always be possible to obtain good quality measurements in such a test, a reliable and efficient numerical simulation of crash testing is therefore very useful. This paper presents finite element simulations of a 3-rail steel road traffic barrier under vehicle impact. The performance levels defined in Australian Standards AS5100 Clause 10.5 for these barriers are checked. The numerical simulations show that the barrier is able to meet low performance levels. However, the maximum deceleration is higher than the acceptable limit for passenger protection. If present, a kerb launches the vehicles into the barrier, allowing for the possibility of overriding the barrier under certain circumstances, but it redirects the vehicle and reduces the incident angle, which reduces impact force on the barrier. Further investigation into all common kerb profiles on roads should be carried out, as only one kerb profile is investigated in this study.

Comprehensive Utilization of Natural Magnesium-Containing Resources and the Development of MgO-Based Refractories

This paper presents the ways of comprehensive utilization of the natural magnesium containing resources and the trends of the MgO based refractories used in high temperature industries. In the first part, the uses and productions of metal Mg, sorel cement, Mg (OH) 2 fire retardant, light magnesium carbonate, light magnesia and magnesium sulphate are described. In the second part, the developments of MgO based refractories used in steelmaking process, nonferrous metallurgy, cement rotary kiln and waste melting furnace are described from some applied theories, including corrosion resistant and slaking resistant MgO CaO materials, chrome free bricks such as MgO CaO ZrO 2 , MgO MgO Al 2 O 3 , MgO MgO·Al 2 O 3 ZrO 2 , MgO MgO·Al 2 O 3 2MgO ·TiO 2 and MgO FeO·Al 2 O 3 , and MgO containing monolithic refractories etc.

Effect of Revolution on Inhomogeneous Deformation of IF Steel in High Pressure Torsion

The effect of revolution on inhomogeneous plastic deformation of HPT processed IF steel was investigated using experimental and simulation approaches. The results indicate that the degree of inhomogeneous plastic deformation increases as the revolutions increase along the radial direction on the transversal plane of disks. In addition, the hardness and the microstructure distributions verify the trend that the effective strain of the HPT processed disks at the early torsion stage is gradually deformed from the edge to the center with the revolutions increases.

Development and future prospect of hot strip rolling technology at Baosteel

Since the 2050 mm hot strip mill was put into operation in 1989, Baosteel has made great achievements in increasing productivity, developing new process technologies and steel products and improving product quality. In the past 18 years from 1989 to 2007 ,Baosteel has constructed five hot strip mills with a total annual capacity of 19.8 Mt. Indices for technology standards, product categories and steel grades, product quality, both technically and economically, take the lead domestically or reached the world class level. As there are many hot strip mills that expected to be put into operation by the end of 2010 ,the overall annual capacity will exceed 30 Mt ,and the product will cover grain oriented （GO） Si steels and alloyed steels.

EFFECTS OF COPPER ION IMPLANTATION ON ANTIBACTERIAL ACTIVITY OF AISI420 STAINLESS STEEL

Antibacterial activity of AISI420 stainless steel (SS) implanted by copper was investigated. Ions extracted from a metal vapor vacuum arc (MEVVA) are sourced with 100keV energy and a dose range from 0.2×1017 to 2.0×1017ions·cm-2. The saturation dose of Cu implantation in AISI420 SS and Cu surface concentration were calculated at the energy of 100keV. The effect of dose on the antibacterial activity was analyzed. Results of antibacterial test show that the saturation dose is the optimum implantation dose for best antibacterial activity, which is above 99% against both Escherichia coli and Staphylococcus aureus. Novel phases such as Fe4Cu3 and Cu9.9Fe0.1 were found in the implanted layer by glancing angle X-ray diffraction (GXRD). The antibacterial activity of AISI420 SS attributes to Cu-contained phase.

Effect of 2-mercaptobenzothiazole concentration on sour-corrosion behavior of API X60 pipeline steel:Electrochemical parameters and adsorption mechanism

We investigated the effect of the 2-mercaptobenzothiazole concentration on the sour-corrosion behavior of API X60 pipeline steel in an environment containing H_(2)S at 25°C and in the presence of 0,2.5,5.0,7.5,and 10.0 g/L of 2-mercaptobenzothiazole inhibitor.To examine this behavior,we conducted open-circuit potential(OCP),potentiodynamic polarization,and electrochemical impedance spectroscopy(EIS)tests.Energy dispersive spectroscopy and scanning electron microscopy were also used to analyze the corrosion products.The results of the OCP and potentiodynamic polarization tests revealed that 2-mercaptobenzothiazole reduces the speed of both the anodic and cathodic reactions.An assessment of the Gibbs free energy of the inhibitor(△G_(ads)^(■))indicated that its value was less than-20 kJ·mol^(-1)and greater than-40 k J·mol^(-1).Therefore,the adsorption of 2-mercaptobenzothiazole onto the surface of the API X60 pipeline steel occurs both physically and chemically,the latter of which is particularly intentional.In addition,as the△G_(ads)^(■)dsvalue was negative,we could conclude that the adsorption of 2-mercaptobenzothiazole onto the surface of the pipeline steel occurs spontaneously.The EIS results indicate that with the increase in the 2-mercaptobenzothiazole inhibitor concentration,the corrosion resistance of API X60 steel increases.An analysis of the corrosion products revealed that iron sulfide compounds form on the surface.In summary,the results showed that an increase in the inhibitor concentration results in a decrease in the corrosion rate and an increase in inhibitory efficiency.Additionally,we found that the 2-mercaptobenzothiazole adsorption process on the API X60 steel surfaces in an H2 S-containing environment follows the Langmuir adsorption isotherm and occurs spontaneously.

A Study on the Structural Response of a PSC Inner Containment Dome with Large Openings Due to Prestress Transfer

A linear three dimensional finite element (FE) study has been carried out to examine the structural response of a prestressed concrete (PSC) inner containment (IC) dome of reactor building (double containment system) of a typical Indian Nuclear Power Plant, having large steam generator (SG) openings with due emphasis on the local behaviour of the steel-concrete interfaces at the SG openings, due to initial prestress transfer. The predominant thrust of the study has been placed on the objective of predicting the possibilities of separation at the steel-concrete interface zones adjacent to the embedded plates (EPs) of the SG openings. Two types of modeling and analysis have been made to study the overall and local behaviour of the structure. Prestressing ducts, passive reinforcements and EPs have been included in the models in certain ways. For the FE analysis, the interface zone has been modeled using interface elements, the properties of which were derived from the results of past experiments conducted on steel plate-concrete inter-face specimens. The FE analysis results have been compared with the results of the past two FE analytical studies on the linear behaviour of the same PSC IC dome. Important observations have been made regarding dome deformation and stresses throughout the structure with special emphasis on the local behaviour of steel-concrete interfaces at and around the SG openings.