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焊接低合金高强度钢时,工件焊后经过一段较长的时间常常出现裂纹。这种裂纹时常与扩散氢有关系,所以亦叫氢裂纹。我们知道,产生氢裂的几个重要条件是:出现了扩散氢,冷却过程中形成了对裂纹敏感的微观组织,存在应力,温度在200℃以下。手工电弧焊时,扩散氢主要来自没有保管好而受潮的焊条。烘干焊条还必须遵守规定。例如低碳结构钢的低氢焊条,使用前必须在230～265℃的炉中烘干2小时;低合金结构钢的低氢焊条必须在370～420℃
Welding low-alloy high-strength steel, the workpiece after welding a long period of time often cracks. This crack is often associated with the proliferation of hydrogen, it is also called hydrogen crack. We know that several important conditions for the generation of hydrogen cracking are: The presence of diffusible hydrogen and the formation of crack-sensitive microstructures during cooling that are stress-dependent and temperatures below 200 ° C. Manual arc welding, the proliferation of hydrogen mainly from the custody of the damp electrode. Drying the electrode must also comply with the regulations. For example, the low-hydrogen steel of low-carbon structural steel must be dried in an oven at 230-265 ° C for 2 hours before use. The low-hydrogen steel of low-alloy structural steel must be dried at 370-420 ° C