Structure of high-chromium cast iron

Mathematical analysis permits quantitative and qualitative assessment of the phase composition of alloys. The distribution of chemical elements over the area of the corresponding metallographic image is shown for the example of copper, which is extremely nonuniformly distributed, even within a single grain. The correlation between the colors of the pixels in the image is assessed by constructing multiple-regression models. On that basis, precise conclusions may be stated regarding the phase combinations and their dispersity in the cast state and after heat treatment.     

Grinding gray cast iron chip

Studies have been made on the grinding conditions for SCh21-40 gray cast iron chip of sizes from 10 × 2 × 0.2 to 20 × 5 × 0.5 mm in vibrating mills containing various media. During dry grinding, the mean particle size falls for 6 h, but after 7 h there is agglomeration. Grinding in the presence of distilled water is most effective when the mill body cooling system is switched off. The grinding in that case is accelerated by a factor of 1.5–2.Deceased.Translated from Poroshkovaya Metallurgiya, No. 11 (359), pp. 7–11, November, 1992.     

Directional solidification of white cast iron

Several studies of the ledeburite eutectic (Fe-Fe₃C), in pure Fe-C alloys have shown that it has a lamellar morphology under plane front growth conditions. The structure of ledeburite in white cast irons, Fe-C-Si, consists of a rod morphology. It is generally not possible to produce plane front growth of Fe-C-Si eutectic alloys in the Fe-Fe₃C form, because at the slow growth rates required for plane front growth, the Fe₃C phase is replaced by graphite. By using small additions of Te, the growth of graphite was suppressed, and the plane front growth of the ledeburite eutectic in Fe-C-Si alloys was carried out with Si levels up to 1 wt pct. It was found that the growth morphology became a faceted rod morphology at 1 wt pct Si, but in contrast to the usual rod morphology of white cast irons, the rod phase was Fe₃C rather than iron. It was shown that the usual rod morphology only forms at the sides of the two-phase cellular or dendritic growth fronts in Fe-C-Si alloys. Possible reasons for the inability of plane front directional solidification to produce the usual rod morphology in Fe-C-Si alloys are discussed. Also, data are presented on the spacing of the lamellar eutectic in pure Fe-C ledeburite, which indicates that this system does not follow the usual λ² V = constant relation of regular eutectics. Formerly Graduate Student, Department of Materials Science and Engineering, Iowa State University.     

铸铁轧辊激光合金化

在轧辊表面通过添加强碳化物形成元素,在适当的激光照射工艺条件下原位生成陶瓷相,得到以亚共晶组织为基,密集分布微米级陶瓷颗粒,同时保留较高残余奥氏体,形成强韧相间的激光合金化区.控制合金过程残余奥氏体量,可防止微裂纹的产生,在使用过程阻止裂纹的扩展.经过表层激光合金化处理的铸铁轧辊,过钢量可提高一倍以上.     

Diffusional titanium coatings on cast iron

The application of diffusional titanium coatings on cast iron from metal melts is investigated. The proposed technology ensures the formation of wear-resistant titanium coatings on cast iron. The composition, structure, and properties of the titanium coatings and the subsurface layer are studied, as well as the process of coating formation on cast iron.     

Interaction of modifiers with liquid cast iron

The effects of some chemical elements and complex modifiers and certain technological operations (gas blowing, the sequence of introduction of additions, etc.) on the oxygen activity in and the surface tension of iron-carbon melts are studied. Correlations between these characteristics and the shape of graphite inclusions in cast iron are found.     

High-chromium cast iron sintered of sprayed powders

The paper examines basic technological characteristics of high-chromium cast iron powders resulting from gas or water melt spraying. Sintering of billets made of these powders is investigated. It is shown that Fe-Cr-Mo-Cr powder alloys can combine high hardness and thermal stability. Therefore, they are candidate materials for operation in intensive wear and at high temperatures. __________ Translated from Poroshkovaya Metallurgiya, Vol. 46, No. 3–4 (454), pp. 111–115, 2007.