利用高温显微镜，对碳钢氢腐蚀裂纹的愈合过程进行原位、 实时观察，通过录象记录了整个裂纹愈合实验过程.结果表明，裂纹在加热到630℃左右时， 发生明显愈合而变小变细.实验中造成的CH4气体散失和内部裂纹表面化使得实验结果与真 实情况有一定的偏差，观察得到裂纹闭合的临界温度630℃低于实际裂纹闭合温 度.发生氢蚀裂纹愈合的机制是热扩散，动力是氢蚀气泡长大导致的塑性变形能Es.在 Fe、C和H原子扩散足够快的情况下，氢蚀裂纹愈合的条件是Es大于2γ/r(γ为界面 表面张力，r为气泡半径或裂纹半长).
The in-situ observation of hydrogen-attacked cracks healing in carbon steel had been done by high-temperature microscope.The whole cracks healing process was recorded at the same time.The results show that the c racks became obviously thinner when heated under 630℃.The escaping of methane a nd inner crack exposure on specimen surface make a certain difference between th is experiment and true condition,the analysis indicates the cracks healing tempe rature in experiment is lower than actual system.The healing of hydrogen attacke d cracks is closely related to heat diffusion of Fe and C atoms in steel.The dri ving force of crack healing results from the plastic deforming energy Es i nduced by the growth of hydrogen attacked bubbles or cracks.The critical conditi on of healing of bubbles or cracks is Es ≥2γ/r (where γ is the surface tension,r is the radius of bubbles or half length of crack).
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