MoldMaking Technology

MAY 2017

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Mold Materials 14 MoldMaking Technology —— MAY 2017 This schematic demonstrates the positioning of the as-cast ingot above the molten slag. As melt- ing continues, the molten steel passes through the slag bath and solidifies at the base of the mold. Factors Affecting Toughness There are two primary factors that affect toughness levels. One is the homogeneity of the steel, which is the level of banding or segregation of the alloying elements and/or alloy carbides. The other is micro-cleanliness, which is the amount of undesirable, non-metallic inclusions (NMI). Once the primary melting and ladle metallurgy processes have been completed, the molten steel is cast into ingots. The high melt temperature and the large volume of molten steel poured into each ingot mold results in a relatively slow solidi- fication rate. As the ingot solidifies from the surface towards the core, the nature of the process results in alloy segregation. Essentially, this is a variation in the steel's chemical composi- tion throughout the cross section of the ingot. This alloy segregation may be alleviated to some degree in the production cycle by adding an annealing process that will promote diffusion and also during the mechanical working that occurs during the forging and/or rolling processes. That is, as the ingot is mechanically worked into its final dimensions as a plate, bar, flat and so on, the carbide and alloy net- works are broken down and more uni- formly dispersed. The degree of forging and rolling plays a major role in provid- ing for a homogeneous material. To improve homogeneity and the microstructure of the steel, and to mini- mize the level of non-metallic inclu- sions, an additional step in the manufac- turing process of the mold steel known as electroslag remelting (ESR), or a more advanced variation known as protec- tive/pressurized electroslag remelting (PESR), may be implemented. For nearly 50 years, BORIDE Engineered Abrasives has developed and manufactured abrasive products for industrial and consumer applications. We provide the highest quality abrasive products through our three unique brands, BORIDE Engineered Abrasives, Falcon Tool Company and Adamas Laboratory including Mold Polishing Stones Accessories, Diamond Compounds owders, and General Industrial Tool Room Supplies and Equipment. BorideAbrasives.com · 800.662.0336 · FalconTool.com COMMITTED TO PROVIDING THE HIGHEST QUALITY ABRASIVE PRODUCTS. BorideAbrasives.com FalconTool.com VISIT US AT AMERIMOLD: BOOTH 1110 Electroslag remelting. The ESR pro- cess takes the initially cast ingot and remelts it under very controlled condi- tions. One end of an as-cast ingot is welded to a fixture and held vertically above a mold containing a molten slag bath. The remelting is initiated when the end of the electrode is brought into proximity with the molten slag. The

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