. Railway mechanical engineer . nd j-ields readily to any strain that may be puton it. Such material is frequently used for tanks, and becauseof its ductility and comparative freedom from damage byheating, is admirably suited for welding. Structural steel,bar steel and boiler plate contain about .15 per cent to .25per cent carbon and have a tensile strength of about 60,000lb., while the soft low carbon material has only about 52,000to 55,000. Ship plate is required to have a tensile strength of in an o.\y-acetylene weld of about 50,000 lb. Neither ofthese materials will weld boiler steel, boil
. Railway mechanical engineer . nd j-ields readily to any strain that may be puton it. Such material is frequently used for tanks, and becauseof its ductility and comparative freedom from damage byheating, is admirably suited for welding. Structural steel,bar steel and boiler plate contain about .15 per cent to .25per cent carbon and have a tensile strength of about 60,000lb., while the soft low carbon material has only about 52,000to 55,000. Ship plate is required to have a tensile strength of in an o.\y-acetylene weld of about 50,000 lb. Neither ofthese materials will weld boiler steel, boiler plate or shipplate, so that the rupture will occur outside the weld whenthe section of the weld is the same as the section of the piece,so that in making tests of welded pieces, it is necessary toknow accurately the character of the material being weldedbecause if \\elder Jones makes a weld in soft tank steel andSmith makes one in bar steel, the first will break outside ^;5^ir* :•. ^^ ■ Jty- - ^^. ■ •^■ •V ?: / ^. ■©■ ■^ ^ 1 Fig. 4—Good oxy-acetylene weld made with Fig. 5—Film of foreign matter, probably Fig. 6—Inter-granular cracl<s in strainedrather high carbon steel. Note presence of oxide, in oxy-acetylene weld. weld. No defects visible before slip bands as in all good welds. straining, showing that films were very thin. from 58,000 to 68,000 lb. and in the heavier sections requiresas high as .30 per cent carbon. It has been found by experience that the higher the carbonthe more difficult it is to get a satisfactor}- weld and themore danger there is of injuring the metal being a metallurgical point of view this is entirely naturaland to be expected. It is also evident that a weld made witha given welding rod or electrode can have only a givenstrength. If this strength is greater than that of the materialbeing welded, the test piece will always break outside of the of the weld and the latter in the weld with a probable
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectrailroadengineering
