Cast iron program focuses on research.Reports on an assortment of ongoing research projects that are adding to the already large body of knowledge of cast irons was the focal point of this year's cast iron program. R.W. Heine, University of Wisconsin-Madison “University of Wisconsin” redirects here. For other uses, see University of Wisconsin (disambiguation).
A public, land-grant institution, UW-Madison offers a wide spectrum of liberal arts studies, professional programs, and student activities. , who, for decades, has been a regular contributor to this body of knowledge, this year discussed the high incidence of graphite flotation in ductile iron castings (91-057). This often occurs, he said, because most ductile irons are of hypereutectic hy·per·eu·tec·tic
Having the minor component present in a larger amount than in the eutectic composition of the same components. composition in the range of %C + 1/ 3%Si [is greater than] 4.3. In these irons, the first phase formed during solidification should be primary graphite beginning near the graphite liquidus temperature and with growth continuing down to the beginning of the eutectic solidification temperature. Upon reaching a critical size, the graphite spheroids may float in the molten iron and produce a flotation layer in the upper regions of a ductile iron casting. The carbon percentage in the iron and the saturation level expressed as carbon equivalent are major contributors to the potential for flotation to occur, Heine explained.
He also discussed several base iron compositions to limit the risk of flotation. Thermal analysis of ductile iron revealed that significant solidification events occur in the temperature region above eutectic solidification. "Flotation is the most obvious result of such proeutectic solidification in hypereutectic irons," Heine said. "Casting properties such as solidification expansion or contraction, shrinkage feeding behavior and nodule nodule: see concretion.
In geology, a rounded mineral concretion that is distinct from, and may be separated from, the formation in which it occurs. count, tensile properties, and microstructures are influenced by this proeutectic stage." He suggested that additional research is needed to better understand the problem of flotation and to learn to control it.
C.R. Loper lope
intr.v. loped, lop·ing, lopes
To run or ride with a steady, easy gait.
A steady, easy gait.
[Middle English lopen, to leap, from Old Norse , Jr. and A. Javaid, University of WisconsinMadison, followed with their study on heavy-section ferritic ductile iron castings (91-106). They found that nodule count or changes in nodularity do not necessarily alter yield strength and only moderately decrease tensile strength. On the other hand, they pointed out that elongation values are reduced. The constant yield strength found in ferritic ductile irons, they said, is noteworthy and assures that static design criteria will be met in heavy-section castings even if a full spheroidal spheroidal /sphe·roi·dal/ (sfer-oi´d'l) resembling a sphere.
resembling a sphere. graphite structure is not achieved.
The usage of cored wire has become a popular method of adding reactive, easily oxidized oxidized
having been modified by the process of oxidation.
see absorbable cellulose. and trim elements to molten metal baths, especially in Europe. J. Rotella, SKW SKW Schweizerischer Kosmetik- und Waschmittelverband (Swiss union of cosmetics and detergents)
SKW Strike Warfare Alloys, and R. Mickelson, Burnham Corp., reported on their work in which a high-magnesium ferrosilicon fer·ro·sil·i·con
An alloy of iron and silicon used in the production of carbon steel. alloy (in cored wire) was used to produce ductile iron in an operating production facility (91069). The results of numerous trials showed cored wire to be capable of producing good quality ductile iron in a production environment. The technique was used to desulfurize de·sul·fur·ize
tr.v. de·sul·fur·ized, de·sul·fur·iz·ing, de·sul·fur·iz·es
To eliminate sulfur from (petroleum, for example).
de·sul , nodulize and preinoculate molten iron. As a result of successful trials, the calcium carbide, porous plug desulfurizing system used in conjunction with a cupola was eliminated.
The distribution of nodules Nodules
A small mass of tissue in the form of a protuberance or a knot that is solid and can be detected by touch.
Mentioned in: Leprosy in ductile cast iron (91056) was the subject of a presentation by T. Skaland, Sintel/Div. of Metallurgy, Trondheim, Norway, and O. Grong, Norwegian Institute of Technology The Norwegian Institute of Technology, known by its Norwegian acronym NTH (Norges Tekniske Høgskole), was established in Trondheim in 1910, and existed as an independent technical university for 85 years, after which it was merged into NTNU . The researchers stressed the effects of microstructure on cast iron properties, which, they explained, are determined during solidification and the subsequent solid-state (eutectoid eu·tec·toid
Of or relating to a eutectic mixture or alloy.
A eutectic mixture or alloy.
Relating to a eutectic mixture or alloy. ) transformation. The number and size of graphite nodules, they said, affect the mechanical and thermal properties of ductile cast iron, so it is important to provide a quantitative description of the nodule distribution in these irons.
K.G. Davis and J-G Magny, PMRL/Canmet, studied the tensile strength of 25-mm-thick gray iron plates cast in permanent iron molds and in sand molds (91-119). They found that part strength was controlled mainly by the iron composition, with variables such as pour temperature and mold type producing very minor effects. An expected correlation between graphite flake size and strength was not realized. The authors explained that despite claims that graphite irons cast in permanent molds are stronger than iron of similar composition cast in sand molds, there was no significant difference between the strength of parts cast in the two different molds.
Interest in austempered ductile iron (ADI) remains high despite slow progress in its applications. B. Kovacs, AFC Technical Center, presented his study of the heat treating of ADI (91-075). His work dealt primarily with the effects of austenitization, quenching and austempering on the mechanical properties and microstructure of ADI castings. What he found was that both temperature and time duration of the various stages in the heat treat cycle has a marked influence on both mechanical properties and microstructure. For example, Kovacssaid, a shorter-than-optimum austenitizing time causes the formation of metastable met·a·sta·ble
Of, relating to, or being an unstable and transient but relatively long-lived state of a chemical or physical system, as of a supersaturated solution or an excited atom. and/or unstable austenite aus·ten·ite
A nonmagnetic solid solution of ferric carbide or carbon in iron, used in making corrosion-resistant steel.
[After Sir William Chandler Roberts-Austen (1843-1902), British metallurgist. , which can result in stressing the part during machining. On the other hand, longer-than-optimum austenitizing time causes bainite formation, which reduces the ductility and the impact strength of ADI parts.
While it appears that little attention is given these days to white cast irons, such as NiHard I, IV and high-chrome alloys, G. Laird II, U.S. Bureau of Mines, is studying these irons with the goal of improving their wear properties (91-055). His report systematically explained the effects of composition and heat treatment upon white cast iron microstructures.