Science: Weld It!

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Today the U.S. is building ships, soon at a rate of two or even three a day, with speed and economy that was inconceivable in World War I—and building them better.

Today 1040's tight machine-tool bottleneck is being broken.

Tomorrow the U.S. may begin building steel airplanes as light as today's welded aluminum planes.

All these things have become possible because of steady but unadvertised advances in the science and art of welding. For the use of welding has made the major difference between the U.S. arms smithing of 1941-42 and 1917-18.

In sheer racket the shipyards of 1918 were rivaled only by the Western Front, for into every 10,000-ton freighter were battered over a half-million rivets. In many modern ships nearly all these rivets have been eliminated. Result is that shipyards today are much quieter, and to gapers outside their guarded walls the chief evidence of activity within is the firefly flashing of arc welders clambering among the hulls.

Even the steel frames of factories and shipways now abuilding are quietly welded together. Silenced for good is the awful din of the structural riveter who clattered up against the U.S. sky in the '20s, a splendid symbol and at the same time an infernal nuisance.

Technological Revolution. Unlike soldering, welding does not consist merely of sticking two objects together with metal glue. Instead it fuses them into one piece, almost as if they were recast. The village blacksmith did a crude form of welding when he heated two iron rods to the melting point and hammered them together till they fused, but modern welding is a much more efficient operation.

Commonest form of welding used today is arc welding. An arc welder has for his tool a device that holds a pencil-sized metal rod carrying a heavy (around 200 amps) electric current of low voltage. When he brings the rod close to the metal to be welded, the current leaps across the near-contact, forming a blinding arc whose temperature—some 6,500° F.—melts both the rod and the metal being welded into tiny molten pools which quickly cool into solid metal. Since the welder's rod (called an electrode) melts down like a candle, he carries a quiverful of rods with him as he works.

A welded product is strongest at its welds. Reason: as the high-grade steel in the melting electrode is deposited, it is protected—as the mill-rolled steel which is being welded was not protected—from contamination by the air's oxygen and nitrogen. These are excluded by another gas formed by the electrode's coating (paper pulp and sodium silicate), which shields the melting metal from the air.

So hot is the welding arc that if it is held more than an instant on one spot, it will eat a hole through a thick steel plate. With his brilliant sputtering arc always in motion, a masked welder "knits" a seam by laying molten steel deposits endlessly atop each other.

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