The role of hydrogen in welding shielding gas
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Recently, a friend told me that when welding stainless steel, he uses a mixture of nitrogen and hydrogen as a shielding gas for welding. I have a minor question: if hydrogen is present in metals, doesn’t that lead to hydrogen embrittlement? Why would anyone use a hydrogen-containing gas mixture as a shielding gas? What role does hydrogen play in this process? What impact does the hydrogen content have on the results?
I’ve never heard of using hydrogen as a shielding gas; don’t you know that?
Dry hydrogen is commonly used as a reducing protective atmosphere in furnaces for brazing stainless steel; it can reduce the oxide film on the surface of the stainless steel and prevent further oxidation of that surface during brazing. Generally, the dew point of hydrogen is required to be below -40°C, but it is also necessary to consider that the dew point of the shielding gas should be suitable for the brazing temperature and the composition of the base material. The lower the brazing temperature, the more stable the oxide film on the stainless steel surface, which in turn requires a lower hydrogen dew point. The advantage of using hydrogen as a protective atmosphere is that it enables continuous operation of the brazing furnace, facilitating mass production ； No flux is required during the brazing process, and the welded parts remain shiny; no surface cleaning is needed after welding ； It can be used with a wide variety of optional filler metals ； The welding cost is low under mass production conditions. However, when using hydrogen as a protective atmosphere, attention must be paid to production safety; when the air contains 4% to 74% hydrogen, combustion can occur, resulting in **.
Reply to 3# snifflily: Heard about it for the first time. Hydrogen is flammable and explosive, and its penetration into welds is harmful; many carbon steel and alloy steel welds require dehydrogenation heat treatment. Who has the detailed technical explanation mentioned by the original poster? ? ?
This shielding gas is quite special; I’ve heard of it for the first time. I’m not sure what welding method it’s used for Welding it together probably won’t work, right? Keep pushing forward; looking forward to the appearance of experts! ! !