This work, a part of the investigation on the state analysis of steel, was carried out to develop a systematic method for isolation and determination of nitrogen as solid solution, and various nitride precipitates in a low carbon steel. The procedure is as follows:
The steel sample is connected as an anode and dissolved into 150 ml of 1% NaCl-5% EDTA electrolyte (pH 6) with a current density of 50 mA/cm
2 for 3.5 hr. Remove the anode, and the residue is collected into a beaker by making use of methanol and is allowed to stand for 45 min. Filter and wash with methanol.
Transfer the paper and residue to a beaker, add 100 ml of 2% EDTA solution (pH 5) and shake for 60 m in. Filter and wash with 0.01M EDTA solution and determine nitrogen in cementite from filterate by Distillation-Nessler (photometric) Method.
Return the paper and residue to the beaker, add 30 ml of HCl (1 to 1) and 2 ml of 30% H
2O
2 and boil gently for 10 min. Filter and wash with water and determine nitrogen as nitride (A1N) from filterate by Distillation-Nessler (photometric) Method.
Nitrogen as solid solution and as unstable nitride such as iron and manganese nitride is determined from the electrolyte by Distillation-Titration Method.
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