Potential risk of hydrogen embrittlement of Zn-Ni coated high strength steel
نام عام مواد
[Thesis]
نام نخستين پديدآور
Md Saimon Islam
نام ساير پديدآوران
Montoya, Arturo
وضعیت نشر و پخش و غیره
نام ناشر، پخش کننده و غيره
The University of Texas at San Antonio
تاریخ نشرو بخش و غیره
2016
مشخصات ظاهری
نام خاص و کميت اثر
85
يادداشت کلی
متن يادداشت
Committee members: Govindaraju, Madhavrao; Maldonado, Victor
یادداشتهای مربوط به نشر، بخش و غیره
متن يادداشت
Place of publication: United States, Ann Arbor; ISBN=978-1-369-44024-9
یادداشتهای مربوط به پایان نامه ها
جزئيات پايان نامه و نوع درجه آن
M.S.
نظم درجات
Mechanical Engineering
کسي که مدرک را اعطا کرده
The University of Texas at San Antonio
امتياز متن
2016
یادداشتهای مربوط به خلاصه یا چکیده
متن يادداشت
Within the aircraft industry, high strength steels have been used for aircraft components (e.g., main landing gear, fasteners, etc). These steels have traditionally been protected using cadmium electroplating. As a result of the carcinogenic nature of cadmium, its use has been severely restricted. Electroplated ZnNi has been identified as a replacement material for the cadmium coating. Demonstration plating lines have been implemented in both Air Force and NAVAIR depots. However, the effects of hydrogen generated from differences in electrochemical potential between the ZnNi coating and exposed steel at a defect site have raised concern. The objective of this work is to determine the potential effect of hydrogen on the susceptibility of ZnNi coated 4340 steel to Hydrogen Embrittlement. In this work, susceptibility of the substrate AISI 4340 steel to HE as a function of cathodic potential will be shown. Slow strain rate tests (SSRT) of smooth bar samples made of high strength AISI 4340 are being conducted to determine susceptibility to HE. In the first set of SSR experiments, bare steel samples were exposed to a NaCl immersion environment while being held at one of five different electrochemical potentials. The effect of potential on time to failure and other properties will be explored. A second set of SSR tests were performed under atmospheric exposure conditions at 84% RH. This value of RH is above the deliquescence point of NaCl and was controlled within the enclosed SSR test cell using a saturated solution of Sodium Sulfate at the bottom of the cell. NaCl salt was deposited on the SSR sample gauge section by a salt spray technique. Filter paper soaked in saturated NaCl solution was used to act as a salt bridge for the reference and counter electrodes under atmospheric condition. The effect of electrochemical potential on the cracking behavior of the atmospherically exposed samples will also be described. SEM characterization of the fractured samples was performed to validate embrittlement. Results from this effort will be used by both the Air Force and Navy to assess the need for enhanced risk based inspection of ZnNi coated steel parts. Engineering modeling was done for different defect sizes on the sample and results were used to validate engineering modeling approaches to predict corrosion and cracking performance during system design.
موضوع (اسم عام یاعبارت اسمی عام)
موضوع مستند نشده
Mechanical engineering; Materials science
اصطلاحهای موضوعی کنترل نشده
اصطلاح موضوعی
Applied sciences
نام شخص به منزله سر شناسه - (مسئولیت معنوی درجه اول )