Pickling The Forgings

The forgings were then pickled in a hot solution of either niter

cake or sulphuric acid and water at a temperature of 170 deg.F., and

using a solution of about 25 per cent. The solution was maintained

at a constant point by taking hydrometer readings two or three

times a day, maintaining a reading of about 1.175. Sixty forked or

one hundred single rods were placed in wooden racks and immersed

in a lead-lined vat 30 by 30 by 5 ft. long. The rack was lowered

or lifted by means of an air hoist and the rods were allowed to

stay in solution from 1/2 to 1 hr., depending on the amount of

scale. The rods were then swung and lowered in the rack into running

hot water until all trace of the acid was removed.

The rod was finally subjected to Brinell test. This shows whether

or not the rod has been heat-treated to the proper hardness. If

the rods did not read between 241 and 277, they were re-treated

until the proper hardness is obtained.

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