材料科学与工程外文文献翻译--灰铸铁的凝固结晶过程

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1、  PDF原文：http:/ 中文3350字 本科毕业论文  外文文献及译文     文献、资料题目： Solidification Of Gray Cast Iron 文献、资料来源： Scripta Materialia 文献、资料发表（出版）日期： 2003.10.19     院  （部）：  材料科学与工程学院  专     业：  材料成型及控制工程  班     级：   姓     名：  

2、 学     号：   指导教师：   翻译日期：     1 外文文献：   Solidification of gray cast iron Abstract    This article investigates the solidification of hypo, eutectic and hypereutectic gray cast irons, using novel techniques developed bythe authors. The nature of the reveal

3、ed macro and microstructure suggests that the solidification mechanism is different from that usually accepted. Keywords: Solidification； Gray iron 1. Introduction     Several authors have studied the solidification of eutectic gray cast iron of flake graphite morphology (GI)17. Commonly,

4、the eutectic solidification unit is represented by a nearly spherical shape of austenite and graphite, as shown in Fig. 1. There is general agreement to consider that austenite and graphite grow cooperatively, being both in contact with the liquid phase. This picture of the solidification of GI is s

5、upported by the morphology of the graphite flakes, that resemble a rosette, as shown in Fig. 2, and by the fact that the inclusions, generally associated to the microsegregation at the last to freeze melt, are located between such units.    Steads reagent reveals the microsegregation of ph

6、osphorus in GI, and it can delineate the units schematically represented in Fig. 1 in high P irons, usually referred to as eutectic cells 8. Since austenite dendrites are not readily discernible, except in gray irons containing types D and E graphite, their formation and growth characteristics in GI

7、 have received limited attention. Some researchers have considered the role of austenite dendrites in the solidification of GI 2,6,7. There is no doubt that austenite of hypoeutectic GI grows dendritically. On the other hand, most of the literature work state that austenite can grow with other morph

8、ologies when the carbon content reaches or exceeds the eutectic 3,7.    During the last years the authors of the present article carried out investigations that challenged the validity of the more firmly established models of the solidification of ductile iron (DI) 911. The use of a specia

9、lly developed technique, that allows to  2 reveal the solidification macrostructure of DI, combined with the use of color metallography techniques that reveal the microsegregation pattern, showed that the macrostructure of DI is formed by relatively large austenite grains, that contain a very l

10、arge numbers of graphite nodules. This was the case for hypoeutectic, eutectic, and also hypereutectic DI.     The objective of this study is to investigate the solidification mechanism of GI by using the micro and macroscopic techniques, successfully applied for DI in earlier studies. Exp

11、erimental methods 2.1. Materials     The melts utilized in the present study were produced by using a 50 kg medium frequency  induction melting furnace. Low manganese pig iron, steel scrap and ferroalloys were used as raw materials. Melts were cast in resin bonded sand moulds to produ

12、ce round bars of 20, 30 and 46 mm diameter. Table 1 lists the chemical composition of the alloys used. The melts were alloyed with Cu and Ni in order to provide enough austemperability to carry out the DAAS macrography technique, which is described below. 2.2. Micrographic technique    The

13、 color etching technique reveals the solidification microstructure through the use of a reagent that brings up the microsegregation patterns generated during solidification 12. The etching reagent is made of 10 g NaOH, 40 g KOH, 10 g picric acid and 50 ml distilled water. It must be prepared and handled with great care, since it is caustic and toxic. Etching is carried out at 120  (278 F) for about 2 min.  Fig. 1. Schematic illustration of the solidification unit of eutectic GI.