Term of Award

Fall 2024

Degree Name

Master of Science in Applied Engineering (M.S.A.E.)

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Department of Manufacturing Engineering

Committee Chair

JingJing Qing

Committee Member 1

Mingzhi Xu

Committee Member 2

Haijun Gong

Abstract

This research investigated the liquid metal embrittlement (LME) of hot-dipped galvanized structural steel. The relationship between stress and failure time was analyzed to evaluate the potential presence of a critical stress threshold beyond which LME may occur. A testing apparatus to induce axial stress was designed and assembled in-house. A36 low carbon steel was tested in this study. Different deadweight loadings were applied to the testing sample along the axial direction. The test temperature was maintained by a programmable furnace while the sample gauge section was submerged in a molten zinc bath. Failure time and total displacement of the steel samples were determined using the testing apparatus. Tests without zinc were performed for comparison. Variation parameters of the tests included axial stress and the presence/absence of zinc. Based on results, the samples tested in the zinc bath exhibited shorter failure times versus the samples tested without zinc for a given stress. The difference between failure times for samples tested with and without zinc increased as the stress decreased. At higher stresses, the samples tested without zinc displayed higher total displacements upon failure than the samples tested without zinc. Failure displacements of samples tested with zinc appeared to increase with failure time. No determinate trend was identified for samples tested without zinc. The samples tested with zinc at higher stresses exhibited lower failure displacements and shorter failure times compared to the samples without zinc, indicating LME. Interrupted testing combined with tensile testing and fractography analysis confirmed the occurrence of LME. For lower stresses, samples tested with zinc had significantly shorter failure times and increased failure displacements versus the samples tested without zinc. It was noted that lower stresses resulted in both longer failure times and sample exposure times to zinc. It was hypothesized that the longer failure times and sample exposure times at lower stresses was due to zinc corroding the steel and reducing the gauge section, producing higher effective stresses and total displacement. Based on the data, a stress range was tentatively identified beyond which LME may occur for A36 steel. Due to variations present in sample grip length, the displacement data was used for qualitative analysis. Further analysis is required to validate the trends in displacement data.

OCLC Number

1478265188

Research Data and Supplementary Material

No

Download

Share

COinS