In 2013, as the eastern span replacement of the San Francisco-Oakland Bay Bridge was drawing to a close, 277 vertical steel rods to improve the seismic stability of the replacement were tested under tension using three-inch-diameter bolts. Within two weeks, 32 of the steel rods had snapped. 277 of these rods were used in the $6.5 billion construction project, but only 96 were accessible. Metal testing suggested hydrogen embrittlement during the manufacturing of the rods may have caused the failures. Thankfully, this was able to be corrected before the bridge opened, but it was a major setback in the construction.
Hydrogen embrittlement is a serious concern in construction and manufacturing, with steels and iron being among the most vulnerable materials. Due to their small size, hydrogen atoms are capable of permeating solid metals. They can also be introduced through various manufacturing steps, such as when the metal is molten or during welding, electroplating, or cleaning. In excess, the presence of hydrogen can weaken the metal, making it more prone to cracking and failure. Hydrogen embrittlement tends to cause catastrophic fracture failures, making it vital that it is caught before weakened material is used and put under stress.
Proper precautions can prevent most hydrogen embrittlement, focused mainly on minimizing contact between the metal in question and hydrogen sources during production and post processing. Hydrogen embrittlement can be prevented. Process parameters must be optimized to allow the metal to remain at temperature long enough so that the hydrogen can diffuse out of the metal during a process called low hydrogen annealing. This is usually a lengthy process that requires the proper amount of time and temperature for the hydrogen involved.
Laboratory testing to determine the quantity of hydrogen in metals is therefore a vital part of quality control. Whether it is testing material during the fabrication process to prevent hydrogen embrittlement or before a heat treatment to determine the minimum time necessary for baking, having a hydrogen determinator like the H836EN in your lab is critical to any steel or iron production. Fill out the form below to learn how the H836EN can determine hydrogen in steel and iron in our latest app note.