Fracture failure analysis of cover plate bolt of aircraft

doi:10.13251/j.issn.0254-6051.2023.10.046

Abstract

Abstract: A bolt for the wing cover plate of an aircraft fractured after service for some time. In order to find out the fracture mode and cause of the bolt, observation on appearance and fracture surface, metallographic structure examination, hardness testing, energy dispersive X-ray spectroscopy (EDS) analysis, hydrogen content testing and hydrogen embrittlement test were carried out. The results show that the fracture mode of the bolt belongs to delayed brittle cracking induced by hydrogen embrittlement. High material strength of the bolt leads to high sensitivity to hydrogen embrittlement, which is the internal cause for the hydrogen embrittlement fracture. Local surface corrosion leads to hydrogen absorption, which is the direct cause for the hydrogen embrittlement fracture. Such failure can be effectively prevented by adjusting the heat treatment process of the bolts so as to properly reduce their strength under the premise of meeting the design requirements as well as strengthening the corrosion protection for the bolts.

Key words: bolt, ML30CrMnSiA steel, hydrogen embrittlement, fracture, corrosion

CLC Number:

TG115

Yin Xiaojian, Xu Yongchun, Zhang Bing, Feng Derong, Sun Xiaojun, Zhang Qinying. Fracture failure analysis of cover plate bolt of aircraft[J]. Heat Treatment of Metals, 2023, 48(10): 297-301.

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