Heat Treat, Penetration Highlighted.Of the 10 Steel Committee (Div. 9) presentations, the majority focused on preventing defects and treating steel castings to enhance quality. In their presentation (154), S. Kuyucak, P. Newcombe and R. Zavadil, CANMET/Materials Technology Laboratory, discussed austenitic manganese steels [1.2% carbon, 13% manganese (Mn)], which suffer from intergranular embrittlement Embrittlement A general set of phenomena whereby materials suffer a marked decrease in their ability to deform (loss of ductility) or in their ability to absorb energy during fracture (loss of toughness), with little change in other mechanical properties, such . They explored the effect of heat treatment (solution annealing annealing (ənēl`ĭng), process in which glass, metals, and other materials are treated to render them less brittle and more workable. and water quench quench, v to cool a hot object rapidly by plunging it into water or oil. quench to put out, extinguish, or suppress; to cool (as hot metal) by immersing in water. ) and residuals (aluminum, nitrogen and phosphorus) on impact toughness. Experiments were performed on test blocks cast in Grade B3 and Grade C Mn steel. The authors found that a step-down in annealing temperature did not significantly improve toughness in 1- and 3-in. sections, but reduced distortion in 1-in.-thick plates. As-cast impact toughness increased with larger grain size. Quench water temperatures offered a convenient way to check quench efficiency. A higher temperature anneal To take the brittleness out of metal, plastic or certain carbon composites. Performed in the preparation of new products or in their restoration, annealing is accomplished via a heat treating process. can recover some toughness lost due to high nitrogen and aluminum content. Data suggested that more phosphide phosphide Any of a class of chemical compounds in which phosphorous is combined with a metal. Phosphides exhibit a wide variety of chemical and physical properties. Phosphides that are rich in metal have high melting points and are hard, brittle, and chemically inert; these eutectic formed at lower temperature near the solidus with increasing phosphorous phos·pho·rous adj. Of, relating to, or containing phosphorus, especially with a valence of 3 or a valence lower than that of a comparable phosphoric compound. content. In their exploration of steel penetration in sand molds (130), J.O. Barlow, K.D. Hayes, T.S. Piwonka and D.M. Stefanescu, Univ. of Alabama-Tuscaloosa, developed mathematical models to predict mechanical and chemical penetration. The chemical penetration model shows that when no carbon is present in a green sand mold, penetration always will occur. Foundry experiments demonstrated the validity of their models. Variables that most affect mechanical penetration are metallostatic head, metal velocity and mold aggragate grain size. To eliminate this penetration, the authors recommended a mold coating, decreased flow rate into the mold and aggregates that are less susceptible to wetting. |
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