Copper Hydrogen Embrittlement (Steam Embrittlement)

Hydrogen in the welding area reacts with oxygen in copper to form water vapor. The vapor cannot escape and forms bubbles that rupture the structure and cause cracks. This mainly happens when the copper contains oxygen, e.g., cast copper. So you need to use clean, low-oxygen material and keep the welding zone dry to prevent hydrogen from entering. If you preheat the area well before welding and cool it slowly, the risk of such cracks drops significantly.