Hydrogen Visualization in Steels Using Ag Decoration Method

Abstract

The relation between hydrogen distribution and metallographic microstructure was investigated by means of Ag decoration technique for a SUS304 austenitic stainless steel, and martensitic and spheroidized SCM440 steels precharged with hydrogen. Preferential distribution of Ag particles was seen on the slip lines of the deformed and hydrogen-charged SUS304 stainless steel, suggesting that the slip lines act as hydrogen trap sites. The martensitic SCM440 steel showed almost no selective Ag deposition, indicative of apparently homogeneous distribution of hydrogen. This is probably because the distribution of dislocations with relatively high concentration and the fine structure including lath boundaries etc. acting as hydrogen traps is homogeneous. The spheroidized SCM440 steel showed almost no Ag deposition on the coarse cementite particles and the Ag particle distribution on the other areas did not show clear selectivity. This result suggests that the hydrogen does not diffuse through the cementite particles. The smallest Ag particle size observed by means of atomic force microscope was in the order of 10 nm. Though the minimum size of the Ag particle does not necessarily indicate the resolution of the hydrogen visualization, Ag decoration technique is useful to observe the hydrogen distribution.

Effect of grain refinement on hydrogen embrittlement behaviors of high-Mn TWIP steel

“…Previous study reported that the diffusible hydrogen atoms tend to accumulate at high stress concentration sites under a load [24]. In addition, Akiyama and Matsuoka [25] confirmed from Ag decoration technique carried out during tensile test that hydrogen accumulated at grain boundaries where some slip lines intercepted in a deformed SUS304 austenitic steel. Plastic deformation gives rise to stress concentration at grain boundaries due to pile-up of dislocations.…”

Behavior of hydrogen in a low carbon high strength steel

“…Silver decoration treatment was performed without stress loading in the present study. Akiyama and Matsuoka [7] reported that Ag particles were observed preferentially at slip lines in the deformed and hydrogen-charged SUS304 stainless steel after silver decoration treatment. We need to conduct silver decoration treatment with stress loading since hydrogen embrittlement occurred when the tensile stress is loaded to the specimen as shown in Fig.…”

“…Silver decoration technique is a method that utilizes reduction reaction of Ag ions in a potassium silver cyanide aqueous solution, caused by hydrogen atoms evolved from the specimen surface [7]. We can distinguish the distribution of hydrogen as the Ag particles on the specimen surface with metallic microstructure.…”

Interfacial hydrogen localization in austenite/martensite dual‐phase steel visualized through optimized silver decoration and scanning Kelvin probe force microscopy

“…Therefore, the only remaining issue for hydrogen mapping is multi‐scale hydrogen mapping consists in a sufficiently high spatial resolution that reveals even evading hydrogen at interfaces such as grain boundaries. Candidate methods for this hydrogen mapping approach include secondary ion mass spectroscopy , hydrogen microprint , and silver decoration technique . In this study, the silver decoration technique was used, since this method ideally enables hydrogen mapping with a nano‐scale spatial resolution (which is determined by the size of the deposited silver particle clusters) across a wide field of view over a millimetre scale to cover the specimen size.…”