Steel nail with a heavy head which is inserted in the mold wall to hasten cooling of the metal at that point.
Unconsolidated sand, sand derived from a rock in which grains separate along their natural boundaries. This includes soft sandstone where little pressure is required to separate the individual grains. See Molding Sand, Naturally Bonded Molding Sand.
A sand containing sufficient bonding material as mined to be suitable for molding purposes. Seldom used today in the metalcasing industry. See Molding Sand.
Navy (USA) Tear Test
A method of evaluating the susceptibility of ship plate to brittle or cleavage type fracture.
Brick with faces arranged so one of the flat faces in inclined toward the other, almost eliminating one end face.
Portland Cement mixed with water only.
Neck Down (Knock-Off, Wafer Core, Washburn, Cameron Core)
A thin core or tile used to restrict the riser neck, making it easier to break or cut off the riser from the casting. See Core.
Reducing the cross sectional area of the metal in an area by stretching.
Reduction in area concentrated at the subsequent location of fracture when a ductile metal is stressed beyond it yield point in tension.
Elongated acicular crystals, tapering at each end to a fine point, as martensite.
Special agents such a boron which markedly increase the hardness of steel.
Negative Quenching (Negative Hardening)
Accelerated cooling in water or oil, from a temperature below the critical range. See Quenching.
Negative Thermoie Heat Exchange
In shell molding, improving the mass-surface ratio by simulating profile geometry of pattern or core cavity on the underside; will boost running temperature of high projections by 25%. See Shell Molding.
Nesh (Hot Short)
A British term applied to metal that is weak and ruptures easily under not working conditions.
A structure in which the grains or crystals of one constituent are partly or entirely enveloped in another constituent; an etched section through the crystals resembles a network.
A mechanical twin in ferrite.
Elementary nuclear particle with a mass (1.00893 mass units) approximately the same as that of a hydrogen atom. It is electrically neutral.
New Jersey Sand
A large number of grades of foundry sands mined in southern New Jersey.
Oxidation-resistant alloy 65% Ni, 20% Fe, and 15% Cr.
An element used for alloying iron and steel as well as nonferrous metals; melting point 1455°C (2651°F). Nickel is also a base metal for many casting alloys resistant to corrosion and high temperature oxidation. Nickel’s chemical symbol is Ni. Its formula weight is 58.69, the specific gravity is 8.90, and nickel’s melting point 1,452°C. See Monel, Nimonic, Inconel, Ni-Hard.
Hard white cast iron containing 4% Ni and 2% Cr. See White Cast Iron.
Nil Ductility Transition Temperature (NDDT)
Determined in the dropweight test. Refers to the absence of the ductile fracture appearance and any reduction in area due to the brittle behavior of the steel. See Ductility.
Class of nickel-base cast alloy resistant to stress and to oxidation at high temperatures. See Inconel.
Standard unit of volume in refractories industries; 9 x 4-1/2, 2-1/2 in brick.
A pipe coupling consisting of a short piece of threaded tubing.
A solution of nitric acid in alcohol use as an etching agent in ferrous metallography.
A surface hardening process involving heating in a atmosphere of ammonia or in contact with a nitrogen-bearing material so as to promote the absorption of nitrogen.
Bubbling nitrogen gas through a metal melt under vacuum (as with valve bronze) to improve tensile properties and pressure tightness.
A synthetic liquid resin sand binder that hardens completely at room temperature, generally not requiring baking, used in the Cold Setting process. See Cold Setting Process.
Metallic elements with surfaces that do not readily oxidize in air; e.g., gold, silver, platinum.
Nodular Fireclay (Burley, Burley Flint)
Rock containing aluminous or ferrogenous nodules, or both, bonded by fireclay.
Graphite or carbon in the form of spheroids, characteristically in malleable and nodular iron.
Cast iron, normally gray cast iron, which has the major part of its graphitic carbon in nodular from. See Ductile Iron.
A device creating noise.
The various frequencies making a noise.
A graph that enables one by the aid of a straight-edge to read off the value of a dependent variable when the value of two or more independent variables are given.
Nondestructive Testing (Inspection)
Testing or inspection that does not destroy the object being tested or inspected.
A negative term, refers to alloy in which the predominate metal or solvent is not iron. See Alloy.
Nonferrous Metal Casting
Metal casting done with a nonferrous metal, in which the molten metal is poured into a mold, cooled, and allowed to solidify. See Nonferrous.
Nonferrous Metal Processing
The processing of a nonferrous metal, such as by melting, alloying, or casting. See Nonferrous.
Concentration of alloying constituents that have low melting points in those portions of a casting that solidify last.
Steel in which the pearlite is completely laminated. See Pearlite.
Heating a ferrous alloy to a suitable temperature above the transformation temperature Ac3, followed by cooling at a suitable rate, usually in still air to a temperature substantially below the transformation range.
Small size ingot with notches to facilitate breakage for remelting.
A test specimen which is notched. Used in impact or fatigue tests.
A two-step basic flake resin with no thermosetting properties, applied to sand in shell molding process as a mold or solution. See Shell Molding.
Pouring spout of the bottom-pour ladle. See Ladle.
A thick-walled tubular refractory shape set in bottom of a ladle through which steel is teemed.
Nozzle Pocket Brick
A refractory shape set in bottom of a ladle containing a recess in which nozzle is set. See Ladle.
Abbreviation for normal temperature and pressure reference point, zero centigrade 760 mm mercury pressure.
The nucleation is the beginning of phase transformation and is indicated by the appearance of a small cluster of atoms or molecules to form the basic crystal structure or small solids called ‘nuclei’. The structure of the crystal may change into one or more unstable intermediate crystals and form critical nuclei of a new solid phase.
The first structurally determinate particle of anew phase or structure that may be about to form. Applicable in particular to solidification, recrystallization, and transformations in the solid state.