Development of a non-destructive technique for the detection of hydrogen embrittlement in high-strength steels

高强度飞机级钢合金必须不含氢，否则可能会发生突然而彻底的失效，即所谓的“氢脆”。最近一个引人注目的氢脆例子发生在旧金山新海湾大桥的30多个3英寸螺栓断裂，因此在交付之前，就需要价值2500万美元的维修。由于腐蚀，氢可以在部件的使用寿命内引入，但它也可以是加工过程中的残留物，例如电镀。在电镀过程中，一些氢不可避免地被引入到钢中，必须在电镀后的短时间内通过热退火(烘烤)去除这些氢；这种方案避免了氢脆，并构成了“正常”的工艺实践。对于非正常的做法，烘焙被推迟或缺席。可以容忍多大的延误？找回碎片的可能性和安全性是可能的吗？只有在能够可靠地确定该部件既不含氢(至少低于某一阈值)，也不存在氢在此期间引起的损坏的情况下。这一合作研究项目将针对工业界有关高强度钢氢脆的实际问题进行。它的目标是确定钢的哪种物理性能受氢的影响最大，并选择或开发一种非破坏性测试方法，使人们能够确定制造的部件没有氢及其相关损害。

High-strength aircraft grade steel alloys need to be free from hydrogen, otherwise a sudden and complete failure, know as "hydrogen embrittlement", may occur. A recent and spectacular example of hydrogen embrittlement occurred when more than 30 3'' bolts at the new Bay Bridge in San Francisco broke, so that even before delivery, 25M$ worth of repairs were required. The hydrogen can be introduced during the service life of the component, due to corrosion, but it can also be a remnant of the processing, for example electroplating. During the plating, some hydrogen is unavoidably introduced into the steel and this must be removed by a thermal anneal (bake) within a short time span following the plating; this protocol avoids hydrogen embrittlement and constitutes "normal" processing practice. For off-normal practice, the bake is delayed or absent. How much delay can be tolerated ? Is it possible and safe to recover the piece ? Only if it can be established reliably that the piece contains neither hydrogen (at least, below a certain threshold) nor damage induced by hydrogen in the interim. This collaborative research project will be undertaken in response to actual questions from industry with regard to hydrogen embrittlement of high-strength steels. Its goal is to determine which physical property of steel is most affected by the presence of hydrogen and to select or develop a non-destructive testing method that allows one to ascertain that a manufactured part is free from hydrogen and its associated damage.