Effects of H content on the tensile properties and fracture behavior of SA508-III steel |
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| Affiliation: | Key Laboratory for Anisotropy and Texture of Materials Ministry of Education, Northeastern University, Shenyang 110819, China |
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| Abstract: | SA508?III steel was charged with different hydrogen (H) contents using a high-pressure thermal charging method to study the ef-fects of H content on the tensile properties and evaluate the H embrittlement behavior of the steel. The results indicate that the ultimate ten-sile strength remains nearly unchanged with the addition of H. In contrast, the yielding strength slightly increases, and the elongation signifi-cantly decreases with increasing H content, especially at concentrations exceeding 5.6× 10?6. On the basis of fractographic analysis, it is clear that the addition of H changes the fracture mode from microvoid coalescence to a mixture of river patterns and dimples. Carbides are strong traps for H; thus, the H atoms easily migrate in the form of Cottrell atmosphere toward the carbides following moving dislocations during tensile deformation. In addition, stress-induced H atoms accumulate at the interface between carbides and the matrix after necking under three-dimensional stress, which weakens the interfacial bonding force. Consequently, when the local H concentration reaches a critical value, microcracks occur at the interface, resulting in fracture. |
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| Keywords: | stainless steel tensile properties fracture hydrogen content carbides |
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