Advanced Materials Research
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Vols. 287-290
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Vols. 284-286
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Vols. 282-283
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Vol. 281
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Advanced Materials Research Vols. 284-286
Paper Title Page
Abstract: Researched on the low carbon steel by mineral component ore phase structure of mould powder and its slag film under optical microscope. The result shows that the glass phase, quartz, and pyroxene in the mould powder helped to the slag film turn into glass. The melilite and wollastonite in the mould powder can promote the formation of melilite, and wollastonite can promote the formation of cuspidine in the slag film. The structure of the slag film is even and the main structure is glass phrase, the rate of crystallization is low, the crystallized mineralogical phases was melilite, the cuspidine did not appeared, which is good for lubrication. The content of glass phase, quartz and pyroxene in the mould powder of the low carbon steel should be increased, the content of wollastonite and fluorite should be reduced.
1253
Abstract: The maximum nonmetallic inclusion size and void of bearing steel has been analyzed using statistics of extreme values (SEV) in this study, and the influence of the maximum nonmetallic inclusion and void size on fatigue life of bearing steel has been discussed as well. Scanning electron microscopy (SEM) was used to measure the inclusion and void size, and the identification of inclusion type has been carried out by energy dispersive spectrometer (EDS). The results show that there are small hard round oxides or sharp TiN inside or beside the soft MnS strip in steels, single MnS strips and small clustered Al2O3 are also present. Most of voids in steels are branched rod-like or feathery, and the size of void is much smaller than inclusion for all steels. Therefore, the void is not the fatigue orgin for bearing steels. By adopting the criterion of return period (T) at 200, a serial analysis shows that the relation between inclusion/void size and fatigue life for steels is inverse proportion except B steel. This results from that larger inclusion could not only initialize crack, but also increase the propagation path of crack and accelerate fracture.
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Abstract: This paper discusses the effect of different loading analysis on crack initiation life of wheel/rail in the contact region. A simulated three dimensional (3D) elastoplastic model of a wheel/rail contact is modelled using the fine mesh technique in the contact region by using Finite Element Method FEM code ANSYS 11.0 software. Different loads of approximately 70, 80, 90, 100, 110, 120, 130 and 140 KN were applied to the wheel tread during the running surface of the railhead to simulate stress distribution (Von Mises) and a life prediction of the crack initiation. Stress analysis is performed and the fatigue damage to the railhead surface is calculated numerically by using a multi-axial fatigue life of crack initiation model. Results obtained from previous researches are compared with this research.
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Abstract: Artificial intelligence (AI) techniques and in particular, adaptive neural networks (ANN) have been commonly used in order to Fatigue life prediction. The aim of this paper is to consider a new crack propagation principle based on simulating experimental tests on three point-bend (TPB) specimens, which allow predicting the fatigue life and fatigue crack growth rate (FCGR). An important part of this paper is estimation of FCG rate related to different load histories. The effects of different load histories on the crack growth life are obtained in different representative simulation and experiments.
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Abstract: The morphological changes, dimension and distribution of M/A constituent in different region of X80 acicular ferrite pipeline steel were investigated; the effect of M/A constituents of X80 on Charpy V-impact and room temperature tensile properties were also discussed by OM and SEM. The results show that: the distribution and morphosis of the M/A constituents have strongly effect on the mechanical properties. The uniformly distributed massive M/A constituents with chord less than 2 μm observed in grains of base metal, presents high impact toughness and high tensile strength, and the strip M/A constituents with chord more than 2 μm observed in welded joint samples exhibits low impact toughness and high tensile strength. It is seems that the changes of the morphosis and distribution of M/A constituents induce the hardening effect during the deformation which is the main reason to the different mechanical property.
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Abstract: New 700MPa hot rolled ultra-high strength steels were successfully developed by using Ti micro-alloying technology in CSP line. Experimental methods, such as OM, TEM and chemical phase analysis, were used to study the experimental steel. The microstructure is composed of quasi-polygonal ferrite grains, whose average grain size is about 4μm. Large number of nanometer TiC particles distribute along dislocations. The mass fraction of MX phase is 0.0793wt%, in which the particles smaller than 10nm account for 33.7%. The contribution of precipitation hardening resulting from nanometer particles is calculated as approximate 158MPa.
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Abstract: Lower sulfur content is absolutely necessary for high value-added quality steel, so it is required to reduce sulfur content of product in each link of metallurgical production. Sintering is one of important links to provide blast furnace raw materials. Study on Sulfur existing form in Sinter can provide significant theoretical guide on sulfur distribution in metallurgical production. In this paper, small sintering experiments were carried out and sinter samples with different alkalinities were prepared. The samples were characterized by mineralogical analysis and X-ray diffraction. The results show that Sulfur existing form in Sinter is calcium sulphide (CaS). CaS can not be oxidized and melted down in the following process of blast furnace iron-making and can directly enters into slag for discharge outside the furnace.
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Abstract: In this paper, tundish flux system for high Al TRIP steel’s slab casting was studied. Firstly the thermodynamical calculation of Al-SiO2 reaction was carried out. Secondly 27 groups of chemical compositions of tundish flux were designed using orthogonal method on the basis of thermodynamical results and slag phase diagram. Thirdly the melting point and the viscosity of each group of chemical composition were tested. Then, regression equations of melting point and viscosity were obtained according to experimental data as well as the analysis of the effect of single-factor and double-factors variation on the regression equations. Finally, the optimal design of tundish flux is w(CaO)/w(Al2O3)=1.1-1.2, w(SiO2)<5%, w(MgO)=4%-7%, w(CaF2)=7%-10% and w(Na2O)=5%, which has a relatively low melting point and viscosity, and its physicochemical performance is relatively stable.
1284
Abstract: Based on the actual process for smelting cold heading steel, this article adopts the single-slag process to smelt the low-carbon, low-silicon and high-alumina cold heading steel SWRCH6A, so as to study the effect of technological factors of the smelting process on the change of molten steel component in various working procedures and steel properties. The results show that, the smelting process control level for smelting high-Al cold heading steel using single-slag process is improved, the content change for main elements in the steel, w[Al]t and calcium treatment effect are stable, w[C] and w[Si] have a close relationship with w[P] and w[S]. The calcium yield after calcium treatment by single-slag process has a linear relation with w[Ca], and ηCa=2323.4*w[Ca] -1.040. The maximum calcium yield may reach 21%. All the mechanical properties of cold heading steel exceed the ML08Al standard. The smelting cold heading steel using single-slag process can fully reach the property requirements for cold heading steel grade.
1291
Abstract: The influences of non-mentallic inclusions on the quality and properties of the steel are depended not only on the quantity of inclusions, but also on the type、shape、size、deformation behavior and distribution condition. The effects of lanthanide rare earth(RE) on the shape、size and distribution condition of inclusions in large rudder arm steel casting is investigated. It was proved that the shape and distribution of inclusions could be improved in the large rudder arm steel casting, and the plastic and toughness of the steel can be increased obviously by the rare earth modification. By means of ANSYS finite element analysis software, the stress field distribution around matrix was simulated, and the reaction mechanism of inclusions by modification was clarified.
1297