What Drives Iron Casting Scrap Rates?

Since the beginning of the Iron Age 2500 years ago, all molten iron has contained free-oxygen atoms and those atoms have significantly corrupted its melting and pouring properties. Free oxygen contamination occurs in tiny amounts but those few parts per million (PPM) alter the iron’s behavior and properties. Deoxidized iron’s properties are so different – and so much improved – that an almost-new material grade results. Few metallurgists understand the role free-oxygen atoms play in […]

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Exciting New Properties in Molten Iron

All iron melted via conventional techniques contains free-oxygen atoms. The amount of free-oxygen contamination varies depending upon the melting method and materials melted, but some free-oxygen atoms always exist. Free-oxygen atoms are detrimental to the quality of solidified castings. They offer no benefits – only bad consequences from their presence. Primary steelmakers deal with free-oxygen atoms’ presence by adding aluminum and other high-oxygen-affinity materials. A foundry or any manufacturer that melts iron cannot employ the […]

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Eliminating Iron Casting Surface Defects

Casting surface defects seem to come and go regardless of what the gating specialist may accomplish, or what standards the foundry’s QC depart may change or tighten. Casting surface defects may be gaseous, or they may contain precipitated solid material, but generally such defects fall beyond normal quality-control efforts. Some very capable foundries were at a loss to lower scrap rates until they were exposed to some new control techniques. Determining defect characteristics – whether […]

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Melting Iron Without Forming Slag

Regardless of the iron melting technique — EF or cupola — slag will form during the process. Slag consists of oxides that form during the melting cycle. The driving force for oxide formation is the contact of molten iron with the atmosphere, which forms iron oxide, starting the oxidation process. Iron exposed to the atmosphere starts the chemical reaction that forms iron oxide, and it cannot be stopped unless the contact between molten iron and […]

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Evaluating Cupola Melting and Oxidation Losses

Previous articles in this series have pointed out and hopefully will lead to the understanding that iron oxide supplies the harmful free-oxygen atoms so harmful to iron-melting processes. Iron oxide is produced during the cupola melting cycle. It is not contained in the metallic charge ingredients, and it is produced as the melting process progresses. The cupola melt cycle begins with pristine materials, primarily coke and clean metallic scrap. Blast air entering the cupola through […]

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Optimizing Cupola System Design

Cupola melting cannot be optimized until the melting process has been deoxidized. Molten iron oxidation occurs naturally in cupola melting: It cannot be prevented but it can be countered – offset. Previous reports in this series described the methods and an only-recently-available deoxidation material, Mastermelt DeOX, for achieving total molten iron deoxidation – both initial primary oxidation and re-oxidation that occurs if molten iron is unprotected from atmospheric contact. Very significant savings, many times exceeding […]

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Cupola System Design Optimizes Melting Operations

Previous entries in this series examined the roles iron oxide and free-oxygen atoms for cupola melting processes. Both of these are important factors for foundries seeking to maximize cupola operation. Assuming iron-oxide formation within the cupola has been addressed and countered, the next step for the operators is to make the changes necessary to maximize thermal efficiency of the cupola. During the cupola’s melt cycle, coke is combusted to produce heat. Maximum heat generation happens […]

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Controlling Conditions for Cupola Melting

Iron oxide threatens all iron-melting processes. In cupola melting, much greater amounts of iron oxide are produced during the normal melt cycle than are produced in electric furnace melting. This makes iron oxide’s effect much more pronounced in cupola melting. In EF melting, 20%-30% oxidation loss is the extreme of losses encountered. In cupola melting, in the worst-case scenario, the oxidation losses approach 65%. Carbon oxidation losses remain unknown to this day. When a cupola […]

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Maximizing Cupola Performance

Iron melting operations face the same challenge with electric furnaces and cupola furnaces — molten metal oxidation. Oxidation is caused by molten iron’s contact with the atmosphere. Last year in these pages we addressed in detail the factors that contributed to oxidation in EF melting, and the technology to counter it. Cupola melting faces a greater challenge: a much higher volume of iron oxide produced during the melting cycle. In cupola melting, blast air contacts […]

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A Molten Iron Improvement Strategy

The development of high-quality iron castings begins with melting processes and techniques. You control how it is melted, giving you the final call in determining its quality. Everything depends on you. Molten iron contains desirable and undesirable elements. In a ferrous foundry, you control both of these. From the scrap metal that is the raw-material source for much of the melt come residual elements like chrome, manganese, nickel, aluminum, etc., that may compromise the quality […]

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