Hydrogen embrittlement fracture of bolts can occur under the combined action of hydrogen, material microcracks and stress. Excess hydrogen is the most basic cause of hydrogen embrittlement fracture of bolts. Hydrogen can cause a decrease in the performance of the bolt material and has a tendency to break the hydrogen brittleness, but it does not necessarily cause the bolt to break. Only when the hydrogen content is too much will the bolt break.
The external condition in which the bolt is hydrogen embrittled is that the bolt is subjected to stress. This stress is a continuation of the slow loading process or static loading. Rapid loading does not allow the material microcracks to rapidly expand under the action of hydrogen and break.
Through the above analysis, we can find that the factors affecting the hydrogen embrittlement fracture of bolts have the following rules: the higher the hydrogen content in the bolt, the more prone to hydrogen embrittlement fracture. The higher the strength of the bolt, the stronger the sensitivity to hydrogen embrittlement. Generally, the tensile strength is above. It is necessary to consider the process of bolting diagram affecting the hydrogen embrittlement of alloy steel bolts. Mechanical processing heat treatment pickling electroplating dehydrogenation chemical oxidation hydrogen embrittlement Breaking problem. The greater the stress of the bolt, the more easily the hydrogen brittle fracture occurs. The more defects of the bolt material, the easier it is to accumulate hydrogen, and the more the fracture source of the hydrogen embrittlement of the bolt. The heat treatment has a certain influence on the hydrogen embrittlement of the bolt. The larger the internal stress generated by the heat treatment, the easier it is to adsorb hydrogen, and the more difficult it is to remove hydrogen. Titanium alloy materials have greater hydrogen embrittlement sensitivity than alloy steels, and titanium is more sensitive to hydrogen than titanium. The test method for the evaluation of hydrogen embrittlement fracture and the hydrogen embrittlement fracture test of the test material to evaluate the hydrogen embrittlement of the material has not yet formed a unified international standard.
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