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| >> GLOSSARY OF TERMS |
| N |
| NATURAL AGING Spontaneous aging of a supersaturated solid solution at room temperature. |
| NEEDLE CUTTER STEEL Usually supplied quarter hard rolled, extra precision rolled with sheared edges. Carbon content 1.25?Chromium .15. Usually supplied in a 2" width from .002 to .035. Used for cutting the eye of needle and milling the latch in a latch needle, |
| NETWORK STRUCTURE A structure in which the crystals of one constituent are surrounded by envelopes of another constituent which gives a network. |
| NICKEL (Chemical symbol Ni) - Element No.28 of the periodic system; atomic weight 58.69. Silvery white, slightly magnetic metal, of medium hardness and high degree of ductility and malleability and resistance to chemical aid atmospheric corrosion; melting point 2651?F.; boiling point about 5250?F., specific gravity 8.90. Used for electroplating. Used as an alloying agent, it is of great importance in iron-base alloys in stainless steels and in copper-base alloys such as Cupro-Nickel, as well as in nickel-base alloys such as Monel Metal. Its principal functions as an alloy in steel making: (1) Strengthens unquenched or annealed steels. (2) Toughens pearlitic-ferritic steels (especially at low temperature). (3) Renders high-chromium iron alloys austenitic. |
| NICKEL SILVER Copper base alloys that contain 10-45% Zn. and 5-30% Ni. ? |
| NICKEL STEEL Steel containing nickel as an alloying element. Varying amounts are added to increase the strength in the normalized condition to enable hardening to be performed in oil or air instead of water. |
| NITRIDING Process of surface hardening certain types of steel by heating in ammonia gas at about 935-1000?F.., the increase in hardness being the result of surface nitride formation. Certain alloying constituents, principal among them being aluminum, greatly facilitate the hardening reaction. In general, the depth of the case is less than with carburizing. |
| NITRIDING STEEL Steel which is particularly suited for the nitriding process, that is, it will form a very hard and adherent surface upon proper nitriding (heating in a partially dissociated atmosphere of ammonia gas). Composition usually .20-.40 carbon, .90-1.50 chromium, .15-1.00 molybdenum, and .85-1.20% aluminum. |
| NON-FERROUS METALS Metals or alloys that are free of iron or comparatively so. |
| NON-METALLIC INCLUSIONS Impurities (commonly oxides), sulphides, silicates or similar substances held in metals mechanically during solidification or formed by reactions in the solid state. |
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