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Welding Techniques Employed: In connection with the use of higher-strength steels, other steels of special characteristics, any material intended for low-temperature service, or where special welding procedures are required, it is recommended that a set of plans showing exact location and extent of application, together with a description of the material and special welding techniques employed, be placed aboard the vessel. The use of aluminum alloys will be considered for approval for the structural parts of the hull.
Arc Welding.—In the arc-welding processes, an arc is struck between the electrode and the work. Although there are some arc-welding processes in which a carbon or a bare wire is used as an electrode, these are not extensively used in practice. In order to improve the ductility of the molten metal in the arc, techniques must be devised which will eliminate the air from the weld zone so that the molten iron cannot react '.vith the nitrogen and oxygen in the air. If iron :tride, for example, is formed, the metal in the »eld may be brittle and have low ductility.
All of the grades covered in 44.5, 44.7 and 44.9 are intended for fusion welding, but welding technique is of fundamental importance and welding procedure is to be in accordance with approved methods. See Section 30. |
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