外文翻譯--優(yōu)化工藝參數(shù)對(duì)蠕墨鑄鐵微觀組織和性能的影響（英文）

1、Journal of Alloys and Compounds 476 (2009) 728–732Contents lists available at ScienceDirectJournal of Alloys and Compoundsjournal homepage: www.elsevier.com/locate/jallcomOptimization of the process parameters affecting

2、the microstructures and properties of compacted graphite ironSugwon Kim a,?, S.L. Cockcroft b, A.M. Omran aa Division of Advanced Materials Engineering, RCIT, Chonbuk National University, Jeonju 561-756, Republic of Kore

3、ab Department of Materials Engineering, University of British Columbia, Vancouver, Canadaa r t i c l e i n f oArticle history:Received 7 August 2008Received in revised form11 September 2008Accepted 14 September 2008Avail

4、able online 11 November 2008Keywords:Compacted graphite iron (CGI)Alloying elementsMechanical propertiesResidual Mg%Fading timeNodularitya b s t r a c tThis paper investigates various methods of producing compacted graph

5、ite iron (CGI). The process param-eters affecting the mechanical properties and microstructures of CGI were studied. These parametersinclude the chemical composition, holding time, temperature and thickness of the castin

6、g. The resultsindicated that the nodularity increased with increasing percentage of residual Mg, whereas increasingthe Cu content was found to sharply increase the amount of pearlite within the CGI. The amount of Mgdecre

7、ased with excessive hold times and the optimum was found to be approximately 4 min for producingcasts containing between 0.008% and 0.012% residual Mg. Increasing the temperature resulted in some lossor fading in the Mg

8、content and increasing the casting thickness resulted in a decrease in the nodularity.In terms of the mechanical properties, both the tensile strength and hardness were found to increase withincreasing residual Mg conten

9、t and nodularity. Empirical equations were proposed to indicate a relationbetween the nodularity (%), the residual Mg (%) and other parameters.© 2008 Elsevier B.V. All rights reserved.1. IntroductionCompacted graphi

10、te iron (CGI) is a promising engineeringmaterial containing graphite precipitates having a short, stubby,compacted shape with rounded edges in a matrix basically simi-lar to steel [1]. CGI possesses distinctive mechanica

11、l and physicalproperties which are intermediate between those of grey cast ironand ductile cast iron. CGI provides at least 70% higher tensilestrength, 35% higher elastic modulus and approximately double thefatigue stren

12、gth of conventional grey cast iron [2]. Because of theseattributes and its good thermal shock resistance, CGI has foundapplication in the manufacturing of automotive engines, machineparts and rolls for various applicatio

13、ns. In comparison, grey cast ironsuffers from thermal fatigue resulting in a shorter fatigue life and itmay also experience severe heat distortion [3]. In order to controlthe geometry of the compacted graphite within the

14、 CGI structure,it is necessary to carefully control the chemistry and processing asis the case for spheroidal graphite iron (SGI).An acceptable CGI is one in which there is no flake graphite (FG)present in the structure

15、and the amount of spheroidal graphite (SG)is less than 20% – i.e. 80% of the graphite is compacted. Alloying? Corresponding author. Tel.: +82 63 270 2298; fax: +82 63 270 2305.E-mail address: ksw@chonbuk.ac.kr (S. Kim).e

16、lements, such as copper, tin, molybdenum and even aluminum,can be used to change the as-cast matrix from a ferritic matrix toa pearlitic one [5,8–10]. Graphite structure modifiers (nodulizers)include magnesium (Mg) and r

17、are earth metals (cerium, lan-thanum, and so on) [1,4]. Also, titanium extends the working rangeof magnesium in controlling the compacted shape of graphite, butalso inhibits the formation of pearlite in the matrix [2,3,7

18、]. Addi-tional factors affecting the formation of compacted graphite includethe holding time of the liquid metal following modifier addition, thecooling rate during solidification, pouring time and pouring tem-perature [

19、3,5]. These factors also interact with each other and affectthe resulting matrix structure.Regardless of the alloying elements used, the high ferritizingtendency of CGI iron should be taken into account [11]. Cu is oneof

20、 the alloying elements which promotes the formation of pearlitein cast iron [2,6]. However, in several studies, a fully pearlitic struc-ture could not be obtained even at 1.7% Cu when using high-puritycharge materials [5

21、,12,13]. To produce a pearlitic matrix, therefore,it may be necessary to add higher than usual levels of alloyingelements or to make multiple additions of two or three elements[2,14,15]. For example, tin is considered a

22、strong pearlite stabilizerand in one study, a structure containing 95% pearlite was obtainedwith 0.13% Sn [2].The current study was carried out to provide technical datafor the production of CGI with a view to reduce the

23、 incidence of0925-8388/$ – see front matter © 2008 Elsevier B.V. All rights reserved.doi:10.1016/j.jallcom.2008.09.082730 S. Kim et al. / Journal of Alloys and Compounds 476 (2009) 728–732Fig. 3. The effect of holdi

24、ng time on the residual Mg content.Fig. 4. The effect of temperature at 1400 ?C on residual Mg% at different holdingtimes.where Mg is the residual magnesium content in percent and x isthe thickness of the casting in mm.3

25、.2. The effect of the fading timeThe effect of holding time at 1400 ?C (defined as the timebetween when the nodulizer is added to the melt and when thecasting is poured) on the residual Mg% is shown in Fig. 3. It canbe s

26、een that there is a general trend of decreasing residual Mg% (orfading of the residual Mg%) with increasing hold time. Up to approx-imately 3 min the rate of fading is relatively low. At times larger thanFig. 5. The effe

27、ct of holding time on residual Mg% for different methods of injectionmethod.Fig. 6. The effect of Cu contents on Pearlite% for different cast section thicknesses.3 min the fade rate appears to increase up to 7 min, at wh

28、ich timethere is less than 0.001% Mg present in the melt. From this figure,holding times in the range of 4–5 min are required for producingcastings containing from 0.01 to 0.012 of residual Mg%. The changein rate of fadi

29、ng is speculated to be due to fact that initially thereis an input of Mg associated with the Fe–Si–Mg nodulizer goinginto solution, which offsets the loss. Based on the data presentedFig. 7. SEM micrographs for a CGI all