Quantitative evaluation of detection efficiency of the hydrogen microprint technique applied to steel

The detection efficiency of a hydrogen microprint technique (HMT) applied to steel specimens was examined experimentally. Amounts of hydrogen released from the specimen surface were measured by an electrochemical hydrogen permeation method, and the amounts were also evaluated by means of HMT under the same charging conditions as employed for the permeation test. Detection efficiency of conventional HMT was found to be as low as about 1%, but nickel plating of the steel surface was found to increase this efficiency remarkably. This high efficiency by nickel plating was achieved only when the relative humidity of an experimental atmosphere was controlled to 80% or higher. The thus-modified HMT showed a detection efficiency of about 40%. (C) 2002 Elsevier Science Ltd. All rights reserved.