ANALYSIS OF THE HYDROGEN CONCENTRATION IN THE HOT-DIP GALVANIZED AND ELECTROPLATED PRODUCTS MADE OF HIGH STRENGTH STEEL

The results of the hydrogen concentration measurements in selected products, made of steel grade 41Cr4, are presented in the following paper. The reason for this project was the failure of the tower structure and the suspicion of brittle fracture caused by hydrogen in one of the hot-dip galvanized products made of steel grade 41Cr4, found in the wreckage of the tower. Due to the fact that the opinion was formulated on the basis of the results of the hydrogen content measurements in broken products, (20 ppm) it was decided to examine this problem more closely. The hot-dip galvanized and electroplated metal elements were subjected to a hydrogen content test. Two types of samples: with and without zinc coating were prepared for analysis. The analysis was performed using an elemental analyser, the LECO ONH836. Diversification of hydrogen content on the sample cross-section was revealed after the profile of its contents was known. It has been found that a high hydrogen content was observed only and exclusively inside the zinc coating. This means that the presence of the Zn coating in the sample affects the accuracy of the measurement of the hydrogen content and can lead to erroneous conclusions about the hydrogen embrittlement or hydrogen charging of steel. The results of the hydrogen concentration in each case should be considered carefully as the total concentration of the hydrogen content is measured, and not only the hydrogen diffusion responsible for the occurrence of hydrogen embrittlement.