焊缝中氢的扩散行为及影响因素

Behavior and Effect Factors of Hydrogen Diffusion in Weld

扩散氢会在焊缝中引起氢脆、延迟裂纹等,导致结构产生低应力断裂。为了研究氢的扩散行为,采用水银法和气相色谱法测定了逸出的扩散氢量,并采用真空抽取法测试了不同温度下残余氢的释放量。试验表明,扩散氢量不受焊道数量的影响,它的逸出时间随焊道数的增多而增长,逸出速度随合金含量的增多而降低。随着焊后冷速的降低,冷却过程中逸出的氢增多,测定出的扩散氢量减少;测氢试样在100～200℃保温时,逸出氢的总量变化不大,但逸出时间随温度的升高而明显缩短。残余氢量与扩散氢量的多少无关,它与焊缝的含氧量、组织和硬度等有关系。

Diffusible hydrogen in the weld caused hydrogen embrittlement, delayed cracks, leading to fracture at low stress. In order to research the diffusion behavior of hydrogen, mercury method and gas chromatography was adopt to measure the diffusible hydrogen amount. And residual hydrogen amount was measured at different temperature by vacuum extraction method. Result shows that diffusible hydrogen amount have no relation to the numbers of weld, and the more weld numbers, the longer escaping time; the more alloy content, the lower escaping velocity. After welding, the slower cooling rate, the more escaping hydrogen amount, so the less diffusible hydrogen amount could be measured. Between 100 and 200 ℃, the escaping hydrogen amount is stable, but the escaping time declines while temperature is higher. Except diffusible hydrogen amount, residual hydrogen amount is related to oxygen content, microstructure and hardness.