This study incorporated a hydrogen charging method that introduced sufficient hydrogen to embrittle all of the steels examined here, including conventional DQSK (Drawing Quantity Special Killed) and HSLA (High Strength Low Alloy) steels as well as newer DP (Dual Phase) and TRIP (Transformation Induced Plasticity) grades. Hydrogen effects were observable by increased flow stress, decreased ductility, altered neck geometry, altered fracture mechanisms, and introduction of microcracks. While the DQSK exhibited susceptibility to hydrogen embrittlement after straining, its overall susceptibility was less than for the other steels. Despite the higher strength and presence of freshly formed martensite in the TRIP steels, the susceptibility to hydrogen embrittlement was less than that observed in the dual phase steel, an observation attributed to the finer microstructure along with the presence of retained austenite in the TRIP steels. Hydrogen-induced microcracking initiated at interfaces between ferrite and higher strength constituents (e.g. martensite, carbide, etc.), and propagated into the ferrite. In contrast to the cracking behavior in hydrogen-embrittled fully martensitic steels, crack propagation through the martensite islands in dual phase and TRIP sheet steels, does not appear to be an important fracture mechanism. Hydrogen embrittlement in the steels examined here was reversible. Because of the mitigating effects of paint baking and natural aging may not influence the performance of high strength sheet steels in vehicle structures.
Response to hydrogen charging in high strength automotive sheet steel products
Reaktion auf einen Wasserstoffeinsatz in hochfesten Stählen für Kraftfahrzeug-Blechprodukte
2003
9 Seiten, 9 Bilder, 4 Tabellen, 19 Quellen
Aufsatz (Konferenz)
Englisch
Response to hydrogen charging in high strength automotive sheet steel products
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SAE Technical Papers | 2003
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