| Dear mustaffi, Mostly Duplex and super duplex are TIG welded using pure argon, (Some recommend adding of 10% nitrogen to the shielding gas and backing gas for the balance between ferrite and austenite phases and the material superior corrosion resistance, however this make welding difficult as it can cause porosity and contamination of the tungsten electrode unless the correct welding technique is used,to much nitrogen will form a layer of Austenite on the weld surface). Backing / Purging gas should contain less than 25ppm oxygen recommended for optimum corrosion resistance. With regards. P.B.R -------Original Message------- Hi All Can anybody can tell me, what it's the best gases to proceed welds for TIG process on Duplex Steel Material Regards Mus |
Introduction The colour formed when stainless steel is heated, either in a furnace application or in the heat affected zone of welds, is dependent on several factors that are related to the oxidation resistance of the steel. The heat tint or temper colour formed is caused by the progressive thickening of the surface oxide layer and so, as temperature is increased, the colours change. Oxidation resistance of stainless steels However, there are several factors that affect the degree of colour change and so there is no a single table of colour and temperature that represents all cases. The colours formed can only be used as an indication of the temperature to which the steel has been heated. Factors affecting the heat tint colours formed Steel composition The chromium content is the most important single factor affecting oxidation resistance. The higher the chromium, the more heat resistant the steel and so the development of the heat tint colou...
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