Evaluation of Hydrogen Embrittlement for High Strength Steel by Three-Point Bending Test and Application to Zinc Electroplating

Abstract

The hydrogen embrittlement of the SK85 high strength steel sheet was evaluated by three point bending test, and the effect of zinc electroplating and zinc nickel alloy electroplating on the hydrogen brittleness of steel was examined by this method. It was found that the evaluation of hydrogen brittleness for the high strength steel sheet by three point bending test was possible to obtain the effective result. Zinc electroplating made hydrogen brittleness promote by the hydrogen based on the reduction of hydrogen ion during the electroplating, because zinc plating acted as a barrier film for hydrogen evolution from the substrate. The hydrogen brittleness of zinc nickel alloy electroplating was suppressed in comparison with that of zinc plating. It seems that large number of cracks in a film enable the hydrogen diffusion.

Effect of Baking on Hydrogen Embrittlement for High Strength Steel Treated with Various Zinc Based Electroplating from a Sulfate Bath

“…When baking was not performed, H 2 release was confirmed from all the plated specimens. Although the amount of H 2 released varied with the type of plating, the release of diffusible hydrogen 9) related to hydrogen embrittlement at approximately 200°C was confirmed in all the plated specimens. As shown in Fig.…”

Effects of Surface Treatment on Fatigue Property of A5052-H14 and A2017-T4 Aluminum Alloys

“…To observe the impact of hydrogen embrittlement on electroless NiP plating, a three-point bending test was performed using SK85 steel (70 © 4 © 0.5 mm) that had been subjected to high heat treatment, as previously reported. 7) 3. Results and Discussions Table 3 shows the tensile properties of A5052 and A2017 alloys.…”

“…10) We evaluated the hydrogen brittleness of high-strength steel with the zinc-based electroplating on the SSRT three-point bending test and clarified its usefulness. 7) A 5 µm-thick, highstrength steel (SK85, hardness 640HV) film was subjected to the SSRT three-point bending test via electroless NiP plating. Hydrogen embrittlement is characterized by strain rate, and embrittlement is promoted at low strain rates.…”

“…The breaking stress increased slightly when the displacement rate decreased below 0.01 mm/min. This is probably because like ZnNi alloy electroplating, 7,11) diffusible hydrogen, which induces hydrogen embrittlement during the test, penetrated the electroless NiP plating film and was released from the substrate. Thus, the involvement of hydrogen embrittlement was suggested as a factor that hindered the improvement of fatigue strength in electroless NiP plating on A2017 alloy.…”

Inferences of Baking Time on Hydrogen Embrittlement for High Strength Steel Treated with Various Zinc Based Electroplating

“…In the three-point bending test, the load was charged on the barycenter of the test piece, and then we measured load-displacement curves until rupture. Based on the experience gained in previous investigations, we set the displacement rate to 0.01 mm/min [8].…”