The National Geographic Magazine, Volume 81National Geographic Society, 1942 - Geography Indexes kept up to date with supplements. |
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Page 476
... steel . Later the red - hot steel is shaped , in the grip of relentlessly squeezing rollers or under the pounding of one - ton to 100 - ton forging hammers so delicately handled that their skilled operators could crack an egg without ...
... steel . Later the red - hot steel is shaped , in the grip of relentlessly squeezing rollers or under the pounding of one - ton to 100 - ton forging hammers so delicately handled that their skilled operators could crack an egg without ...
Page 477
... steel by use of ammonia , a con- stituent of urine . Tank armor , for instance , is " nitrided " in hot am- monia gas . The sur- face picks up nitrogen which case - hardens the steel . Electricity Strengthens Tanks In a new process for ...
... steel by use of ammonia , a con- stituent of urine . Tank armor , for instance , is " nitrided " in hot am- monia gas . The sur- face picks up nitrogen which case - hardens the steel . Electricity Strengthens Tanks In a new process for ...
Page 479
... steel less likely to break . Mixed with molten steel , it finds and removes weakening oxygen and unites with harmful sulphur to form man- ganese sulphide , which is less objectionable . Into every ton of steel goes at least 121⁄2 pounds ...
... steel less likely to break . Mixed with molten steel , it finds and removes weakening oxygen and unites with harmful sulphur to form man- ganese sulphide , which is less objectionable . Into every ton of steel goes at least 121⁄2 pounds ...
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