A New approach to the Solidification of Ductile Cast Iron.
<body bgcolor="#FFFFFF"> <A name="etchants"> <Font size=3>Abstracts of:</FONT><BR><FONT size=4> "A New Approach to the Solidification of Cast Iron." </FONT> <Font size=3>Etchants used to revealing the microstructure of ductile Cast Iron.</Font> To support theories on nodule formation in ductile cast iron, much use has been made of traditional microstructures, which were etched with etchants like nital or picral. These microstructures revealed little, however, of the original solidification structure of the material. By using color or tint etchants, the primary solidification structure of the matrix is highlighted and makes it possible to explain the solidification process in a completely different way.<BR> Etchant compositions and techniques are presented.(5 images, total size:95 K.)</A><BR> <A HREF="http://members.lycos.nl/cvdv/etchants.htm">Etchants used to revealing the microstructure of ductile cast iron.</A> <IMG SRC="imagessummary/foto3.gif" width=113 height=115 ALT="Example micro-photograph of tint etched ductile iron"> <A name="fecdiagram"> <font size=3>Abstracts of:</font><BR><font size=4> "A New Approach to the Solidification of Cast Iron." </font><font size=3>The Iron-Carbon double diagram, a fundamentally wrong concept?</font> Serial sectioning of a ledeburitic region in gray iron showed that the isolated pearlite islands are sections through compact branches belonging to primary austenite dendrites that enclose the carbide region. <BR> Microscopic examination of a hyper-eutectic white cast iron, after tint etching, showed that the appearance of primary carbide needles is just an optical illusion, caused by needle-shaped austenite dendrites that enclose these carbide regions. <BR>These findings, which can be easily verified, mean that the concept of the Iron Carbon double diagram must be fundamentally wrong!<BR> (13 images, total size:240 K.)</A><BR> <IMG SRC="imagessummary/primcarbidecomp.gif" width=113 height=105 ALT="Example micro-photograph of primary carbide needle"> <A HREF="http://members.lycos.nl/cvdv/FECDIAGR.htm">The Iron-Carbon double diagram, a fundamentally wrong concept?</A> <A name="primsoldci"><font size=3>Abstracts of:</font><BR><font size=4> "A New Approach to the Solidification of Cast Iron." </font><font size=3>Primary Solidification of Ductile Cast Iron.</font> Serial sectioning of 3-D dendrites, found in heavy pouring basins, showed that all graphite nodules are found within austenite dendrite arms. Based on the existance of a stable graphite austenite eutectic, a new theory was proposed, explaining the formation of graphite nodules in ductile cast iron. The whole austenite phase solidifies dendritic. Its growth and branching determines the distribution and dimension of the graphite nodules. <BR> ( 32 images, total size:630 K.)</A><BR> <IMG SRC="imagessummary/primdendritecomp.gif" width=113 height=111 ALT="Example micro-photograph of 3-D dendrite in ductile iron"> <A HREF="http://members.lycos.nl/cvdv/dltweedis.htm">Primary Solidification of Ductile Cast Iron.</A> <A name="dcitheories"><font size=3>Abstracts of:</font><BR><font size=4> "A New Approach to the Solidification of Cast Iron." </font><font size=3>How theories on nodular graphite formation developed.</font> To re-study theories on nodule formation which are so generally accepted seems to be wasted time. The availability of a fundamentally different theory, however, showed that many "known facts" can now be explained in a different way. The popularity of the "Melt theory" caused the once so important austenite dendrites to disappear. Slowly, however, interest for this "remaining 90%" of the material seems to return. The complete survey leaves more than enough room for alternative views! ( 37 images, total size:265 K.)</A><BR> <IMG SRC="imagessummary/melttheorycomp.gif" width=254 height=84 ALT="Example sketch of nodule formation according to the melt theory"><BR> <A HREF="http://members.lycos.nl/cvdv/partone.htm">How theories on nodular graphite formation developed.</A> <A name="nodoud"><font size=3>Abstracts of:</font><BR><font size=4> "A New Approach to the Solidification of Cast Iron." </font><font size=3>Nodular graphite before it was even invented.</font> A literature survey on the period 1900 to 1948 showed that on many occasions nodular graphite had been found in cast iron. Instead of recognizing the importance of this graphite shape, its appearance was theorized away by applying existing views on graphite formation in cast iron. Those missed changes for an early invention of ductile iron shows that some flexibility in thinking mightbe worth while! (...images, total size..kb).</A><BR> <IMG SRC="imagessummary/piwowarsky.gif" width=113 height=79 ALT="Example photograph of nodule formation in cast iron found in 1925"><BR> <A HREF="http://members.lycos.nl/cvdv/nodoud.html">Nodular graphite before it was even invented.</A> <BR><BR><BR><BR><BR><BR><BR> <A name="hypereutectic"><font size=3>Abstracts of:</font><BR><font size=4> "A New Approach to the Solidification of Cast Iron." </font><font size=4>The Hypereutectic region of the Iron carbon Diagram.</font> The formation mechanism of primary graphite is said to be fairly well known. How differently it becomes, however, when all publications that were presented over the last century on this field are put together....A tremendous amount of facts can be found which points to quite a different mechanism than the simple flotation mechanism that is still popular today! Another indication that our ideas about the solidification of cast iron have to be changed dramatically.</A><BR> <IMG SRC="imagessummary/primgraphitecomp.gif" width=202 height=113 ALT="Example sketch of primary graphite formation in cast iron."><BR> <A HREF="http://members.lycos.nl/cvdv/hypereutectic.htm">Hypereutectic region of the iron carbon diagram.</A> <BR><BR><BR><BR><BR><BR><BR> <A name="primgray"><font size=3>Abstracts of:</font><BR><font size=4> "A New Approach to the Solidification of Cast Iron." </font><font size=3>Primary solidification of gray cast iron.</font> Virtually every publication on primary solidification of cast iron starts by stating that so little attention has been paid on this subject. In this literature survey, the majority of publications that appeared on this field from the twenties on, has been collected and evaluated. It was surprizing to notice that all actions that are taken in daily practice to influence graphite formation in gray cast iron, such as super-heating, pouring temperature, inoculation, desulfurization, vacuum melting etc., also influence the primary structure. It is therefore reasonable to accept the idea that changes in graphite morphology are actually the direct result of changes in the morphology of the primary structure and not the result of growth changes of the graphite itself.</A> <BR><IMG SRC="imagessummary/coolingcurve.gif"width=170 height=113 ALT="Example of cooling curve ."> <A HREF="http://members.lycos.nl/cvdv/primarygray.htm">Primary solidification of gray cast iron.</A> <A name="centci"><font size=3>Abstracts of:</font><BR><font size=4> "A New Approach to the Solidification of Cast Iron." </font><font size=3>100 Years of theories on graphite formation in cast iron.</font> In this literature review, the majority of publications that have appeared during the last century and which explained how and by what mechanism graphite in cast iron is formed, has been collected, rubricized and presented chronologically. </A> <IMG SRC="imagessummary/centcicomp.gif" width=146 height=113 ALT="Overview of ideas on graphite formation in cast iron from 1880 to the present day."><BR> <A HREF="http://members.lycos.nl/cvdv/centci.htm">100 Years of theories on Graphite formation in Cast Iron.</A> <A name="ironcarbondiagram"><font size=3>Abstracts of:</font><BR><font size=4> "A New Approach to the Solidification of Cast Iron." </font><font size=3>The Iron Carbon diagram over the years.</font> A collection of Iron Carbon diagrams which were published from 1897 up till the present day. This collection will gradually be expanded.</A><BR> <IMG SRC="imagessummary/zhukovcomp.gif" width=169 height=156 ALT="Example of Zhukov's Iron carbon diagram (1992)."> <A HREF="http://members.lycos.nl/cvdv/ironcarbondiagrams.htm">The Iron-carbon diagram over the years.</A> <A name="newfecdiagram"><font size=3>Abstracts of:</font><BR><font size=4> "A New Approach to the Solidification of Cast Iron." </font><font size=3>Proposal of a new Iron carbon diagram.</font> If the facts as described in the previous pages are combined with the many unexplained events that occur on and around the liquidus lines in the hypoeutectic and hypereutectic region, a new iron carbon diagram can be drawn, in which supercooling of the austenite phase governs the solidification of cast iron. </A> <IMG SRC="imagessummary/fecnewcomp.gif" width=142 height=118 ALT="Corrections in the iron carbon diagram."> <A HREF="http://members.lycos.nl/cvdv/newfecdiagram.htm"><BR>Click here to load the complete page of: Proposal of a new Iron carbon diagram.</A> <A name="graphiteform"><font size=3>Abstracts of:</font><BR><font size=4> "A New Approach to the Solidification of Cast Iron." </font><font size=3>Proposal of a new and general mechanism for graphite formation in cast iron.</font> Undercooled austenite will be supersaturated with carbon. Excess carbon diffuses through the austenite crystalls and is ejected as graphite at suitable sites. 111 planes act as a template for graphite formation. The final shape of the graphite extrusions is determined by the way austenite dendrites grow and branch.</A> <BR> <IMG SRC="imagessummary/graphiteformationcomp.gif" width=141 height=131 ALT="Example of cooling curve ."><BR> <A HREF="http://members.lycos.nl/cvdv/graphiteformation.htm">Proposal of a new and general mechanism for graphite formation in cast iron.</A> <BR><BR><BR><BR><BR><BR><BR> <A name="interestingurls"><font size=3>Abstracts of:</font><BR><font size=4> "A New Approach to the Solidification of Cast Iron." </font><font size=3>Interesting URL's</font></A> <A HREF="http://members.lycos.nl/cvdv/interestingurls.htm"> Links to related sites</A> </body>