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

高强度航空级钢合金需要不含氢，否则可能会发生突然的完全失效，即“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上，超过30个3英寸的螺栓断裂，甚至在交付之前，就需要价值2500万美元的维修费用。氢气可以在组件的使用寿命期间引入，由于腐蚀，但它也可以是加工的残留物，例如电镀。在电镀过程中，一些氢不可避免地进入钢中，必须在电镀后的短时间内通过热退火（烘烤）除去。该方案避免了氢脆，构成了“正常”的加工实践。对于非正常练习，烘培延迟或缺席。我们能容忍延误多久？是否有可能且安全的取回碎片？只有当可以可靠地确定该部件不含氢（至少低于某一阈值），也没有在此期间由氢引起的损坏时，才可以。该合作研究项目将针对工业中有关高强钢氢脆的实际问题进行。其目标是确定钢的哪些物理特性受氢气的影响最大，并选择或开发一种无损检测方法，使人们能够确定制造的部件不受氢气及其相关损害的影响。

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.