RCC-M规范第Ⅱ卷材料篇分析

分析RCC-M规范第Ⅱ卷材料篇的结构、主要内容及相互关系,总结了RCC-M材料篇的主要特点。     

Formation of potassium slag in olivine fluxed blast furnace pellets

Abstract

Mineralogical evaluation of olivine pellets coated with kaolinite, taken from the LKAB experimental blast furnace, shows significant reactions with potassium. Sampling has revealed strong potassium deposition in pellets in the lower shaft close to the wall, but much less deposition towards the furnace centre. Iron reduction and the deformation of the pellets were enhanced in the zone of high alkali deposition. Thin sections of pellet samples were prepared to distinguish amorphous and crystalline slag phases for a better understanding of the formation of the potassium rich slag. Olivine breaks down to various extents to form a SiO₂–FeO–MgO–K₂O glass. The kaolinite coating shows strong reaction throughout the cross-section of the lower shaft to form kalsilite (KAlSiO₄) and K₂O rich glassy slag. Studies of thin sections of the slag products were shown to be very useful in separating amorphous phases such as the K₂O rich glass from the crystalline olivine rim.     

Effect of section thickness and modification on thermal analysis parameters of A357 alloy

Abstract

Thermal analysis technique relies on the cooling curve obtained when the sample is cooled in a sampling cup. This may not represent the cooling behaviour of the real casting. The microstructure developed during solidification depends not only on the nucleation and modification potential of the melt but also on the thermal gradient imposed during solidification by the mould. The factors affecting the thermal gradient are the mould material and casting section thickness. In the present investigation the effect of modification melt treatment, cooling rate and casting section thickness on the thermal analysis parameters of A357 alloy was studied. It is found that the dimensionless heat flux parameter is high for small section thickness castings. The metal/mould interfacial heat flux is high in a copper mould. Thermal analysis parameters of A357 alloy are found to be affected significantly by the combined action of modification, chilling and section thickness.     

Analysis of rolling load generated by pair crossed rolling mill

Abstract

Although a pair crossed rolling mill has a very high control capability of strip crown, a frictional force always occurs in the strip width direction between the strip and the work rolls. An analysis of rolling load was carried out, considering the shear deformation of strip cross-section caused by the frictional force. From the examination of the calculated results for a large-scale mill for production, the following conclusions were obtained: (a) the cross angle hardly influences the rolling force and torque, (b) the thrust force on the roll induced by the frictional force decreases as a result of shear deformation, (c) the thrust factor, i.e. the thrust force divided by the rolling force, is little influenced by the strip deformation resistance and the friction coefficient between the work rolls and the strip during hot rolling, (d) the thrust force applied to the rolls during hot rolling is 3–6% of the rolling force for the cross angle of 1° and this is not an obstacle related to the design of rolling mills.     

Determination of Isothermal Section of Fe-Ni-Zr Ternary System at 1198K

The isothermal section of Fe-Ni-Zr ternary system at 1198K was experimentally determined using diffusion triple technique together with scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). The results indicate that there are seven binary intermetallic phases, Fe2Zr, FeZr2, NiZr2, NiZr, Ni10Zr7, Ni7Zr2, and Ni5Zr, found in the ternary system, the binary compounds NiZr2 and FeZr2 show a homogeneity range and form a continuous solid solution, namely (Fe, Ni)Zr2. Five three-phase sections, γ(Fe,Ni) Ni7Zr2 Ni5Zr, γ(Fe,Ni) Ni7Zr2 Ni10Zr7, γ(Fe,Ni) Fe2Zr Ni10Zr7, (Fe,Ni)Zr2 Fe2Zr Ni10Zr7, and (Fe,Ni)Zr2 NiZr Ni10Zr7, exist in the isothermal section. No ternary compound is observed.