Abstract
When steel components fail in service due to the intervention of hydrogen assisted cracking, discussion of the root cause arises. The failure is frequently blamed on component design, working conditions, the manufacturing process, or the raw material. This work studies the influence of quench and tempering and hot-dip galvanizing on the hydrogen embrittlement behavior of a high strength steel. Slow strain rate tensile testing has been employed to assess this influence. Two sets of specimens have been tested, both in air and immersed in synthetic seawater, at three process steps: in the delivery condition of the raw material, after heat treatment and after heat treatment plus hot-dip galvanizing. One of the specimen sets has been tested without further manipulation and the other set has been tested after applying a hydrogen effusion treatment. The outcome, for this case study, is that fracture risk issues only arise due to hydrogen re-embrittlement in wet service.
Highlights
High strength steels offer multiple design and cost advantages
These tests were performed in air. It should be noted these averages are calculated on three specimens and, to avoid generating a sense of false accuracy, that these averages are calculated on three specimens and, to avoid generating a sense of false experimental deviations corresponding to the 95% confidence interval on the average have been accuracy, experimental deviations corresponding to the 95% confidence interval on the average have included using the expression (1)
The intention was to elucidate whether the fracture was Hydrogen Embrittlement (HE) affected by internal hydrogen uptake of the bolts during their manufacture, or was an EAC issue affected by external hydrogen uptake of the bolts due to the water condensation on a discontinuity of the zinc coating
Summary
High strength steels offer multiple design and cost advantages Their most publicized application is in automotive components, where their use is being promoted by progressively more restrictive CO2 emission control policies. Components manufactured in these steels favor a reduction in emissions and an improved gas mileage thanks to their lightweight design. Other sectors such as oil & gas are prone to take advantage of high strength steels, such as in jack-ups and mooring chains for offshore platforms [1]. The fastener market benefits from high strength steels in terms of cost competitiveness [2]
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