SA508-Ⅲ钢的氢致脆性行为

采用高温高压气相热充氢方法,将氢充入SA508-Ⅲ钢.在常温下,研究了氢与SA508-Ⅲ钢的拉伸变形行为的交互作用,以澄清钢的氢致脆性机理,为核电用钢的安全设计提供理论依据.结果表明,充氢使钢的屈服强度略升高,而钢的断面收缩率明显降低.充氢后钢的拉伸断口由纯微孔聚集型断口转变为韧窝加河流花样复合型断口.钢的屈服强度升高主要归因于在弹性变形阶段氢对位错的钉扎,从而阻碍了位错开动.然而在塑性变形阶段,氢随可动位错迁移并不断富集于碳化物与基体界面处,当氢浓度达到一定值时,造成碳化物与基体之间的结合强度降低,从而引起钢的塑性降低.

Hydrogen Embrittlement Behavior of SA508-Ⅲ Steel

The gas phase thermal charging method was performed for SA508-Ⅲ steel with H charging at high temperature and high pressure. The interaction between H and the tensile deformation behavior was studied at room temperature to clarify the hydrogen-induced brittleness mechanism and provide the basic data for the steel design of nuclear power plant. The results showed that the yield strength of the steel with H charged slightly increases， and the reduction area obviously decreases. The fracture morphology changes from normal micro-void coalescence fracture to mixture of river pattern and dimple fracture due to H charging. The increase of the yield strength ascribes to the pinning effect of H on dislocation，thus the initiation of dislocation can be resisted.During the plastic deformation process， H moves following the moving dislocations and concentrates at the interfaces between the carbides and matrix. Once H concentration reaches the critical value， the bonding force between the carbides and matrix decreases， resulting that the ductility of the steel decreases.