Abstract
Determination of free nitrogen in steel by constant temperature-hydrogen hot extraction method was studied and optimum analytical conditions were established.
1) Lower measured values were obtained with samples that had passed for long time after powdering. 2) The result of 1) was considered to come from the fact that dissolved nitrogen in steel was locked to dislocations and/or formed cluster gradually, thus becoming difficult to be extracted. 3) Higher temperature of environment around samples accelerated these effects, so it must be avoided to heat powdered samples for washing and drying. 4) It is necessary to analyse samples of finer powders soon after powdering. 5) When the sample was analysed under these analytical conditions, free nitrogen could be fully extracted at 400°C.
