夹杂对氢鼓泡形成的影响

INFLUENCE OF INCLUSIONS ON INITIATION OF HYDROGEN BLISTER IN IRON

通过粘接低熔点合金后拉伸,可使纯铁表面氢鼓泡被剖开,露出内部断口形貌．扫描电镜观察和能谱分析表明,氨鼓泡是含H_2的空腔,大多数(88%)鼓泡核附近存在夹杂．这表明含H_2空腔择优在夹杂界面处形成,当鼓泡中氢压产生的应力超过原子键合力(有可能被氢降低)时,裂纹从鼓泡核壁形成,产生断裂花样,氢进入已开裂的鼓泡就使它通过裂纹扩展而不断长大,直至鼓泡破裂,内部氢压释放．

The upper part of hydrogen blister on the surface of α-Fe can be tear off through sticking a layer of melting Cu-Ag alloy and extending, then the fracture surface of the blister can be analyzed by SEM and EDS. The results show that the hydrogen blister is a void with H2 and inclusions appeared at about 88% of the blister nucleus, meaning the void formed preferentially at the interface of inclusions and matrix. When the hydrogen pressure in the blister is larger than that of the cohesive strength, which may be decreased by hydrogen, crack will initiate from the wall of the blister, resulting in fracture surface in its interior. With hydrogen entering into the blister, hydrogen blister grows through crack propagating until it breaks and the hydrogen pressure is released.