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本文采用焊接热模拟高温充氢试样和实际焊接接头试样进行弯曲试验,并用电视录像方法观察和拍摄了氢致延迟裂纹的动态过程,定量地评定了不同材料、不同扩散氢含量和应变量对氢致裂纹敏感性的影响,研究了试样厚度对裂纹形成和扩展的影响。试验结果表明:①焊接热模拟高温充氢试样的弯曲试验方法可以定量评定含氢量和应变量对氢致裂纹敏感性的影响;②厚度为3mm 和5mm 的弯曲试样,裂纹首先在试样内部形核,内部裂纹的扩展领先于表面塑性变形区,所以厚试样的表面塑性变形区并非是氢致裂纹亚临界扩展过程中裂纹前端的塑性区,因而仅从厚试样的表面现象研究裂纹的动态过程是不适宜的。厚度为2mm 的试样表面先裂,裂纹在试样表面裂得快,可以用它来观察氢致裂纹的动态过程;③对试样断口进行了扫描电镜观察,发现随着试样含氢量的增加,IG 增加,QC 的塑性变形痕迹减小,韧窝变细。
In this paper, the bending test was carried out by using the welding heat-simulating high-temperature hydrogen-filled sample and the actual welded joint sample. The dynamic process of hydrogen-induced delayed crack was observed and photographed by the video recording method. Quantitatively, the hydrogen and densities of different materials, On the impact of hydrogen induced crack susceptibility, the influence of specimen thickness on crack formation and propagation was studied. The results show that: (1) The bending test method of hot-charging high-temperature hydrogen-filled samples can quantitatively evaluate the influence of hydrogen content and strain on the hydrogen induced crack susceptibility; (2) Bending specimens with thickness of 3mm and 5mm The internal nucleation and internal crack propagation are ahead of the surface plastic deformation zone. Therefore, the plastic deformation zone of the thick specimen is not the plastic zone at the crack tip in the subcritical hydrogen-induced crack propagation. Therefore, It is not appropriate to study the dynamic process of cracks. The thickness of 2mm specimen pre-cracking, crack crack in the surface of the specimen quickly, you can use it to observe the dynamic process of hydrogen induced crack; ③ the sample fracture was observed by scanning electron microscopy and found that with the hydrogen content of the sample Of the increase, IG increased, QC traces of plastic deformation decreases, dimples thinning.