2009年, 第16卷, 第5期　刊出日期：2009-09-15

  

• 全选
  |

工艺
• Select
  Simulation and prediction of the alkalinity in sintering process based on grey least support vector machine

  SONG Qiang

  中国钢铁期刊网. 2009, 16(5): 1-6.

  摘要 ( )   可视化   收藏

  Prediction of the alkalinity is a difficult problem during the process of sintering .Whether the level of he alkalinity of it is successful or not direct relates to the quality of sinter.By now,there isn’t a very good method due to the high complexity ,high non-linear, strong coupling, high delay-time and etc.A grey support vector machine model was proposed on the basis of the models.The fluctuation of data sequence is weakened by the grey theory and the support vector machine is capable of processing non-linear adaptable information, and the grey support vector machine is a combination of those advantages. The results reveal, the alkalinity of sinter can be accurately predicted through this model by reference to small sample and information. It was concluded that the grey support vector machine model is effective with the advantages of high precision, less samples required and simple calculation.
• Select
  Influence of size of hematite powder on its deoxidation kinetics with H2 at low temperature

  GUO Pei-min

  中国钢铁期刊网. 2009, 16(5): 7-11.

  摘要 ( )   可视化   收藏

  The deoxidation kinetics of hematite ore with various particle sizes with hydrogen at low temperature and reduction mechanisms were studied using the thermogravimetric analysis. Under the same temperature, after particle size of powder becomes thinner from 107.5μm to 2μm, the surface area of powder and the contact area between powder and gas increase, which makes the deoxidation process of hematite accelerate about 8 times, and the apparent activation energy of deoxidation reaction drops to 36.9 kJ/mol from 78.3 kJ/mol because of activity of ore powder improved with refining gradually. Under the same reaction rate, the reaction temperature of 6.5μm powder decreases about 80℃ than that of 107.5μm powder. Thinner diffusion layer also helps accelerate the reaction with powder refining. The higher the temperature, the greater peak of deoxidation rate is; under the same temperature, the greater the particle size, the smaller the peak of deoxidation rate is; both inner diffuse and interface chemical reaction play an important role in the whole reaction process.
• Select
  Gas Ionizationon During Carbothermic Reduction in Microwave Field and Its Effect

  CHEN Jin

  中国钢铁期刊网. 2009, 16(5): 12-16.

  摘要 ( )   可视化   收藏

  Ionization of gas on carbothermic reduction of metal oxides containing coal by microwave heating is studied in the paper. The result of using the conventional heating method to conduct the carbothermic reduction of metal oxides containing coal is obviously weaker than that of the microwave heating in the term of the reduction time, temperature, atom mole ratio of carbon and oxygen. After studied on the cause, it is believed that gas is ionized in carbothermic reduction of solid-solid phrase between metal oxides and coals, which accelerates progress of carbon gasification and significantly improves kinetic conditions of carbothermic reduction.
• Select
  Water Modeling of a Swirling Flow Tundish for Steel Continuous Casting

  YUE Qiang

  中国钢铁期刊网. 2009, 16(5): 17-17.

  摘要 ( )   可视化   收藏

  A conventional turbulence inhibitor is compared with a swirling chamber from the points of view of fluid flow and removal rate of inclusion in the tundish. Comparing the RTD curves, inclusion removals, and the streamlines in water model experiments, it can be found that the tundish equipped with a swirling chamber has a great effect on improving the flow field, and the floatation rate of inclusion is higher than the tundish with a turbulence inhibitor. Because of the introduction of the swirling chamber, the flow field and inclusion removal in a two-strand swirling flow tundish is asymmetrical. Rotating the inlet direction of swirling chamber 60 degree is a good strategy to improve the asymmetrical flow field.
• Select
  Rapid Finite Element Analysis of Bulk Metal Forming Process Based on Deformation Theory

  Peng WANG Xiang-huai DONG Li-jun FU

  中国钢铁期刊网. 2009, 16(5): 23-28.

  摘要 ( )   可视化   收藏

  The one-step finite element method (FEM), based on plastic deformation theory, has been widely used to simulate sheet metal forming processes, but its application in bulk metal forming simulation has been seldom investigated, because of the complexity involved. In this paper, a bulk metal forming process is analyzed by using a rapid finite element simulation method based on deformation theory. The material is assumed to be rigid-plastic, strain hardening. The constitutive relationship between stress and total strain is adopted, whereas the incompressible condition is enforced by penalty function. The geometrical non-linearity in large plastic deformation is taken into consideration. Furthermore, the force boundary condition is treated by a simplified equivalent approach, considering the contact history. Based on constraint variational principle, the deformation finite element method is proposed. The one-step forward simulation of axisymmetric upsetting process is performed by this method. The results are compared with those obtained by the traditional incremental FEM to verify the feasibility of the proposed method.
• Select
  Thermodynamic modeling as a strategy for casting highly alloyed steels

  Peri Reddy.V Sankara Raman Sankaranarayanan

  中国钢铁期刊网. 2009, 16(5): 29-31.

  摘要 ( )   可视化   收藏

  Oxides are encountered in steel plant operations, such as in steel making and continuous casting - in the form of fluxes, slags and refractories. Further, oxidation of some readily oxidizable elements often takes place - leading to certain difficulties in the process. The formation / presence of certain oxides can lead to problems such as clogging of Submerged Entry Nozzle during continuous casting. Difficulties associated with the oxides of Aluminium and Chromium have been reported in the literature. Strategies based on thermodynamic calculations can be used to overcome the problems associated with such oxides. Approaches to enable sustained casting of highly alloyed steels have been taken up in the present study. One of the strategies to avoid the oxidation of Chromium is to add small amounts of other elements (subject to other constraints), which do not cause subsequent problems. The problem has been studied using the Thermo-CalcR software, with related databases; and, the results obtained for different process conditions / generic compositions have been presented in this paper.
• Select
  Research on the Effect of Initial Crown on Hot Rolled Strip Shape

  HU Yu GONG Dian-yao

  中国钢铁期刊网. 2009, 16(5): 32-34.

  摘要 ( )   可视化   收藏

  Based on influence coefficient method, using the software of roll elastic deformation simulation, the effect of entry crown on hot rolled strip shape was researched and analyzed. According to the real condition of certain domestic hot rolled strip factory, the unit crown change from the first stand to the last was calculated when entry crown of hot strip alters. The calculation result shows that the entry crown effect not obviously on the target strip crown at the exit of last stand with the strip shape control reference such as bending force keeping fixed. The reason of calculation was analyzed, the research work refers theory support to strip shape setup modeling and shape control.
• Select
  Investigation on Head and Tail Shape Control in the Vertical-Horizontal Rolling Process by FEM

  Zang Xin-Liang LI Xue-Tong

  中国钢铁期刊网. 2009, 16(5): 35-42.

  摘要 ( )   可视化   收藏

  Using 3D rigid-plastic finite element method (FEM), a numerical simulation model for the non-steady state vertical- horizontal rolling process in roughing trains has been built, and is validated by comparison between simulated and experimental values of width and shape of the stock ends. Aiming to certain 2050 roughing process technologies, short shape control (SSC) of the stock ends was investigated using the model. Based on the simulated results, a new SSC model was developed. Moreover, it can be seen that it is effective for the new SSC model to improve shape of the stock ends from the analyzed results.
• Select
  Application of FEM to Hot Continuous Rolling Process for Inconel 718 Alloy Round Rod

  SUI Feng-li

  中国钢铁期刊网. 2009, 16(5): 43-43.

  摘要 ( )   可视化   收藏

  A finite element model is made for coupled thermo-mechanical analysis during hot continuous rolling process for finished product- Inconel 718 alloy round rod with diameter of 45mm. The stability of that process is discussed by integration of FEM and processing map reported in open literature. The result shows that the stability of Inconel 718 will be analyzed effectively during that process and good stability appears as the initial temperature is 960℃ and the initial velocity is from 0.15 to 0.45m•s-1 or the initial temperature is 980℃ and the initial velocity is from 0.15 to 0.25m•s-1.
• Select
  Improved Pattern Clustering Algorithm and its Application in Recognition of Transversal Thickness Distribution of Steel Strip

  Tang Cheng-Long Shi-gang WANG Qin-hua Liang Wei Xu

  中国钢铁期刊网. 2009, 16(5): 50-50.

  摘要 ( )   可视化   收藏

  Transversal thickness distribution of steel strip in the entry section of cold rolling mill has distinct affections to the flatness and transversal thickness control precision of final products. Pattern clustering method is introduced to steel rolling area and is first time to be used in the patterns recognition of transversal thickness distribution of steel strip. K-means clustering algorithm as the best-known one has the advantage of being easy to implement, it has drawbacks. In this paper, an improved k-means clustering algorithm is presented, main improvement points include the amount of clusters is indirectly determined by experience, the initial clustering points are preselected according to the density queue of data objects and Mahalanobis distance is applied instead of Euclidean distance. Compared to the clustered patterns obtained from the common k-means algorithm, the patterns identified from the improved algorithm is more reasonable. The results of application in one coil further show the improved clustering algorithm is well suitable for the patterns’ recognition of transversal thickness distribution of steel strip. It will do great help in the online quality control system.
材料
• Select
  Influence of Thermal Homogenization Treatment on the Structure and Impact Toughness of H13 ESR Steel

  Ma Dang-shen

  中国钢铁期刊网. 2009, 16(5): 56-56.

  摘要 ( )   可视化   收藏

  High levels of isotropy and homogeneous structure are very important criterion for high quality H13 hot work steel. In this paper, the cast microstructure of H13 ESR ingot and the influence of high temperature diffusion treatment on the structure and impact toughness have been investigated. The results show that: the dendrite arm spacing gradually becomes wide from the surface to the center of ingot and the interdendritic segregation areas always exist large primary carbides particles; by means of high temperature diffusion treatment of ingot prior to hot forging, the banded segregation is nearly eliminated, the annealed structure is more uniform and the isotropy properties have been improved remarkably.
• Select
  Effect of Ultra-fast cooling on the microstructure of large-section bars of bearing steel

  SUN Yan-Kun

  中国钢铁期刊网. 2009, 16(5): 61-61.

  摘要 ( )   可视化   收藏

  The ultra-fast cooling technology of large-section bars GCr15 bearing steel was researched connected with industry practice, the microstructure in different cooling patters were researched by optical microscopy、transmission electron microscopy and energy spectrometer, it was concluded that: the large-section bars of GCr15 bearing steel passed the zone of secondary carbide precipitation quickly through the ultra-fast cooling technology(UFC) the instantaneous cooling rate of which was about 200℃/s, the finishing cooling temperature was higher than Ms, the lamellar spacing of pearlite was thinner and thinner and the micro-hardness was bigger and bigger along with the reduction of re-reddening temperature，the precipitation of network carbide was restrained when re-reddening temperature was 690℃, and fine laminated pearlite was obtained through transformation of pseudopearlition which induced the reduction of the diamond of pearlite grain and refinement of the lamellar spacing of pearlite, ideal microstructures promoting spheroidizing annealing were obtained.
• Select
  Effect of welding processes on tensile, impact, hardness and microstructure of AISI 409M ferritic stainless joints fabricated using duplex stainless steel filler metal

  A.K.Lakshminarayanan

  中国钢铁期刊网. 2009, 16(5): 66-0.

  摘要 ( )   可视化   收藏

  The present investigation is aimed at to study the effect of welding processes such as shielded metal arc welding, gas metal arc welding and gas tungsten arc welding on tensile and impact properties of the ferritic stainless steel conforming to AISI 409M grade. Rolled plates of 4 mm thickness were used as the base material for preparing single pass butt welded joints. Tensile and impact properties, micro hardness, microstructure and fracture surface morphology of the welded joints have been evaluated and the results are compared. From this investigation, it is found that gas tungsten arc welded joints of ferritic stainless steel showed superior tensile and impact properties compared with shielded metal arc and gas metal arc welded joints and this is mainly due to the presence of finer grains in fusion zone and heat affected zone.
• Select
  Effect of Heat Input and Niobium on the Microstructure and Toughness of Coarse Grain Heat-Affected Zone in HSLA Steels

  ZHANG Ying-qiao ZHANG Han-qian

  中国钢铁期刊网. 2009, 16(5): 73-73.

  摘要 ( )   可视化   收藏

  The influence of Nb on the coarse grain heat-affected zone (CGHAZ) microstructure, mechanical property and the transformation kinetics of HSLA steels under different heat inputs, has been investigated. When welded at higher heat inputs (100~60kJ cm-1), impact toughness values of the steel without Nb are much higher than the steel with Nb, and the lowest span is 153J at 60kJ cm-1. But only a little higher values are observed at lower heat inputs (40~30kJ cm-1), and the highest span is 68J at 30kJ cm-1. Dilatation studies indicate continuous cooling transformation start temperatures (Ts) of CGHAZ for the steel with Nb are approximately 15~30°C lower than the steel without Nb at all heat inputs. Under higher heat inputs Nb in solid solution suppress ferrite transformation and promote the formation of granular bainite which has detrimental effect on impact toughness. Under lower heat inputs higher Charpy impact energy values in the steel with Nb are associated with the formation of low carbon self-tempered martensite.
• Select
  Coarsening and Age hardening Behaviors of γˊ Particles in GH742 During High Temperature Treatment

  LI Hong-yu SONG Xi-ping WANG Yan-li CHEN Guo-liang

  中国钢铁期刊网. 2009, 16(5): 81-81.

  摘要 ( )   可视化   收藏

  The coarsening and ageing-hardening behaviors of γ′ particles in a nickel base superalloy have been investigated by field emission scanning electron microscopy (FESEM) observation, coarsening kinetics calculation and microhardness testing when ageing at 1050, 950 and 900℃ for different time. The cube of γ′ particle size and ageing time follows a linear law as predicted by LSW theory. The particle size distributions give better fit with the LSW theoretical distribution. The activation energy for γ′ coarsening is accurately determined to be 245.06±14.42 kJ/mol when considering the effect of temperature on the solution concentrations in matrix. Based on the activation energy, the coarsening kinetics of γ′ particle is predicted as . The microhardness studies indicate microhardness decreases rapidly with ageing temperature increase and when ageing at different temperature for long time, the microhardness has a maximum value which corresponding a critical particles size beyond which the microhardness increase stalls.
• Select
  Abrasive performance of the chromium carbide reinforced Ni3Al matrix composite cladding in different depth

  Li Shang-Ping He-Li Luo Di Feng Xu Cao Xi-e Zhang

  中国钢铁期刊网. 2009, 16(5): 87-87.

  摘要 ( )   可视化   收藏

  The Microstructure and room-temperature abrasive wear resistance of chromium carbide reinforced Ni3Al matrix composite cladding in different depth on nickel base alloy were investigated. The results showed that there is a great difference in microstructure and wear resistance of the Ni3Al matrix composite in different depth. Three kinds of tests, designed for different load and abrasive’ size, were utilized to understand the wear behaviour of this material. Under all three wear conditions, the abrasion resistance of the composite cladding in the depth of 6mm, namely NC-M2, was much higher than that of the composite cladding in the depth of 2mm, namely NC-M1. In addition, the wear-resistant advantage of NC-M2 was more obvious when the size of the abrasive was small. The relative wear resistance of NC-M2 increased from 1.63 times to 2.05 times when the size of the abrasive decreased from 180μm to 50μm. The microstructure of the composite cladding showed that the size of chromium carbide particles, which was mainly influenced by cooling rate of melting pool, as a function of distance from the interface between the coating and substrate was gradual. The chromium carbide particles near the interface were finer than that away from interface, which was the main reason for the different wear resistance of the composite cladding in different depth.
• Select
  A New Ductile Fracture Criteria Applied to Various Deformation Conditions Based on Micro-void Model

  Jian-ke HUANG Xiang-huai DONG

  中国钢铁期刊网. 2009, 16(5): 92-92.

  摘要 ( )   可视化   收藏