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本文利用S4-10型Stereoscan扫描电镜拉伸试验装置,对阴极充氢的Johnson-Matthey纯铁的形变和断裂微观过程进行了动态观察。主要结果如下: 1.随着氢含量的增加(从5.4cm~3/100g增到31.0cm~3/100g),屈服应力略有增加,流变应力和断裂强度显著增加,而断裂应变明显降低。在氢含量高于18.7cm~3/100g以上时,下屈服点和Lüders带消失。2.氢含量低于10cm~3/100g的试样,裂纹优先在晶内滑移面上萌生形核,沿着亚晶界向前扩展,断裂途径大都是与拉伸轴呈45°方向断开。而氢含量大于16cm~3/100g的试样,裂纹易在晶界上开裂,在晶内呈锯齿形向前扩展,与拉伸轴正交方向断开。3.纯铁氢脆的主要特征是:(1)试样表面上滑移线的明显减少,(2)脆性微观断裂形态的形成和增多。这是由于固溶的氢原子降低塑性形变所致。
In this paper, the deformation and fracture microscopic processes of Johnson-Matthey pure iron filled with cathodes were observed dynamically by using the S4-10 Stereoscan scanning electron microscope tensile test apparatus. The main results are as follows: 1. With the increase of hydrogen content (from 5.4cm ~ 3 / 100g to 31.0cm ~ 3 / 100g), the yield stress increases slightly, the flow stress and fracture strength increase significantly, . When the hydrogen content is higher than 18.7cm ~ 3 / 100g, the lower yield point and Lüders zone disappear. 2. The samples with hydrogen content less than 10cm ~ 3 / 100g preferentially nucleate on the intracrystalline slip surface and extend forward along the subgrain boundaries. Most of the fracture paths are at 45 ° to the tensile axis open. On the other hand, when the content of hydrogen is more than 16cm ~ 3 / 100g, the cracks are easily cracked in the grain boundary, zigzag in the grain expands forwardly and is disconnected from the orthogonal direction of the stretching axis. 3. The main features of pure iron hydrogen embrittlement are: (1) a significant reduction of the slip line on the specimen surface, and (2) the formation and increase of brittle microscopic fracture morphology. This is due to the reduction of the plastic deformation of the solution of hydrogen atoms.