Handbook-Non-Ferrous Metals

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WELDING OTHER NON-FERROUS METALS As we said early in this book, almost any metal which can be welded at all can be welded with the oxy-acetylene flame. Titanium is a conspicuous exception to that general rule. For copper, for magnesium and its alloys, and for nickel and its alloys, one of the inert-gas-shielded arc welding processes should always be selected in preference to oxy-acetylene welding if the necessary equipment is available. We shall discuss those metals only briefly in this chapter. However, the copper alloys – brasses and bronzes – are widely used, and can almost always be successfully gas welded, so we shall cover them in greater detail. While only a few people have occasion to weld lead, gas welding is the only logical way to weld that soft metal; a special technique is required, which will be described at the end of this chapter. Copper Alloys – Brasses and Bronzes The major copper alloys fall into three general categories: the copper-zinc alloys, commonly thought of as ”brass”, but frequently labelled ”bronze”; the copper-tin alloys, which are the true ”bronzes”; and the copper-silicon alloys (of which one is brand-named ”Everdur”). In addition, there are aluminum bronzes, and several copper alloys containing up to 30% nickel (”cupro-nickel” and ”nickel silver”, for example). The copper-zinc alloys have from 5% to 40% zinc content. The ”free-cutting” brasses also contain 1-3% lead. Add a little iron and manganese to a high-zinc brass and you get ”manganese bronze”. The copper-zinc alloys can usually be fusion welded only by the oxy-acetylene process. Copper-tin alloys in sheet or plate form are often called phosphor bronze. The term ”phosphor” is derived from the fact that the copper used to make the alloy has been deoxidized by the use of phosphorus. The amount of phosphorus left in the metal after that deoxidation is extremely small. Phosphor bronze may contain as much as 10% tin, or as little as 1.25%. A ”tin-bronze” casting will contain 4.5% to 11% tin. All copper-tin alloys can be oxy- acetylene welded.