Hydrogen-as-a-probe applied to investigate the influence of extraction and preparation methods on TDS spectra of 13CrMo4-5 samples

Abstract

Thermal desorption spectroscopy (TDS) provides rich information on the desorbed hydrogen flow rate activated at different heat energy levels, supporting high-resolution assessment of small-scale features that are preferential trapping sites. TDS spectra are also highly sensitive to hydrogen uptake from the sample’s extraction and preparation methods, whose influence requires further evaluation. In this research, hydrogen-as-a-probe is applied to evaluate the influence of extraction, surface grinding, dwelling time, plate thickness, and sample thickness on TDS spectra of 13CrMo4-5 steel. Validation of TDS results confirms that all hydrogen present in the sample before the TDS measurement, including metallurgical hydrogen and hydrogen uptake from the studied methods, is desorbed during the first heating cycle. Results indicate that peaks 1 and 3 are negligibly influenced by the studied methods. Peak 2 and total hydrogen concentration are significantly influenced by sample extraction and surface grinding methods, which provide the main outcomes of this work. Methods based on severe solid-state distortion, like machine cutting and grit P320, present an increased total hydrogen content of 99% and 142%, respectively. Dwelling time and plate thickness have small influence on hydrogen content. Reducing the sample thickness results in less total hydrogen concentration at a rate of 5.7 at.ppm/mm.