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adopted allowed annealed anvil bar iron become cool become heated become quite cool blister steel borax breaking in hardening brightened carbon case-hardening cast iron cast steel cause central steel centre charcoal chasers cherry-red heat chisel circular cutters circular saws cold chisel compression consequently convenient crack cutting degree of heat dipping drills edge endways entirely quenched flat forging fracture fusible hammer hardening and tempering heated to redness hollow fire ignited fuel immersed inch kinds of articles kinds of tools less liable loam lump malleable mandril hole metal method necessary obvious oil or tallow open fire piece of iron piece of steel placed plate prevent previous to hardening prussiate of potash red heat red-hot lead required to harden rimers rings or collars round sal ammoniac saws screw taps shear steel sides soft steel articles sufficient suitable surface steel swage thickness tongs toughened unequal uniformly heated water foremost wrought iron
Page 79 - ... glass, when cautiously heated and slowly cooled, ceases to present the polarizing effect, and the steel similarly treated ceases to be hard ; and may we not therefore indulge in the speculation, that in both cases a peculiar crystalline structure is consequent upon the unannealed or hardened state ? In the process of hardening steel, water is by no means essential, as the sole object is to extract its heat rapidly, and the following are examples, commencing with the condition of extreme hardness,...
Page 94 - ... clay- They are then placed in the fire, and kept at a light red heat for half an hour, when the contents of the box are emptied into water- Delicate articles, like files, may be preserved by a saturated solution of common salt, with any vegetable mucilage, to give it a pulpy consistence The carbon here spoken of is nothing more than any animal matter, such as horns, hoofs, skins, or leather, just sufficiently burned to admit of being reduced to powder- The box is commonly made of iron, but the...
Page 28 - By this test it will be easy to select such pieces of iron or steel as possess the greatest degree of uniformity ; as the smallest vein of either upon the surface, will be distinguished by its peculiar sign. The hardness and polish of steel may be united, in...
Page 146 - A convenient mode of tempering a great number of articles nt once, and of heating them uniformly, however irregular their shape, is to put them into a proper vessel with as much oil or tallow as will cover them, and then to place them over the fire, or the flame of a lamp, until a sufficient heat is given.
Page 9 - ... in the state of carbonic acid gas. As the carbon and oxygen thus go off, the iron becomes more infusible ; it gets thick or stiff in the furnace ; and the workmen know by this appearance that this is the time to remove it from the fire, and to submit it to the action of the hammer, or the regular pressure of large steel rollers, by which the remaining impurities are forced out, and the metal is rendered malleable, ductile, and totally infusible.
Page 161 - ... hollow jaw, the tongs will then grip them all ; any quantity may be hardened as expeditiously as a single article, if there be sufficient lead. Another thing to be observed is, that the surface of melted lead becomes quickly covered with a skin, which is the effect of the air on the surface, and it wastes the lead so fast that it becomes an object of importance to those who use much lead to check its formation, or to convert it when formed into the metallic state again. Charcoal converts the...
Page 82 - ... form. A rod of good steel, in its hardest state, possesses so little tenacity, that it may be broken almost as easily as a rod of glass, of the same dimensions. This brittleness can only be diminished by diminishing its hardness ; and in the proper management of this point, for different purposes, consists the art of tempering. The colours which...
Page 87 - ... cannot become more heated, consequently the temper cannot become more reduced." But those tools in which a portion only is tempered, and in which the heat for tempering is sup1 Edcs, 80. plied by conduction from other parts of the tool (as described at p. 293), " must be cooled in the water directly the cutting part attains the desired colour, otherwise the body of the tool will continue to supply heat and the cutting part will become too soft.
Page 64 - Malleable iron-castings are at the opposite extreme of the scale, and are rendered externally soft by the abstraction of their carbon, whereby they are nearly reduced to the condition of pure malleable iron, but without the fibre which is due to the hammering and rolling employed at the forge.
Page 195 - ... is lifted by a powerful crane and placed in a perpendicular position in an upright furnace ; an iron coil about 6 inches in depth and about one inch larger in diameter than that of the tube, is placed upon the fire-bars, at the bottom of the furnace, for the tube to rest upon ; beneath this iron coil is placed a piece of plate-iron to prevent the cold air, as it passes through the bars, coming in contact with the extreme end of the tube, and in order to obtain a uniform temperature at the extreme...