In daily life, the stainless steel ANSI B16.5 socket weld flange is mainly used to connect the pipeline and maintain the pipe sealing performance, which is convenient for the replacement of a certain section of the pipeline, Open and inspect pipeline and facilitate the closure of a certain section of pipeline. But in the welding process of the socket weld flange, It's cracking, After the hardness test, it was found that the cracked socket flange was about 80 times higher than the intact socket flange in Leeb hardness, why?
Stainless steel socket flange material is 20#, 304, 304L, 321, 316, 316L, 310S and so on. Pressure rating: 0.6Mpa to 32Mpa, 150Lb to 2500Lb, PN0.25-PN42.0.
Under normal circumstances, the welding current is too large, so that the heat-affected zone of the welding organization reaches the upper transition temperature, and the post-weld cooling rate is too fast, similar to the normalizing process. Causes the socket flange to have a high hardness, a tendency to harden and crack. Can the stainless steel socket flange be lined with carbon steel-lined stainless steel?
An external pressure equipment, its socket flange and equipment socket fitting flange and manhole, whether the use of carbon steel lining stainless steel, with lining it? If it is a non-vacuum external pressure should be no problem, but it should also pay more attention to the substrate, because the substrate will interfere with the lining once it is destroyed. If it is a vacuum, it should be noted that the lining of the stainless steel socket flange is firmly bonded to the substrate because it is possible to vacuum the lining. Therefore, in addition to the edge of the circle welding, it may be necessary to do some plug welding to ensure. The degree of bonding between the liner and the substrate must be high, and the liner must be tested for airtightness after the liner is welded.
What is the difference between stainless steel socket flange forgings and castings: After the metal is forged, it can improve its microstructure and mechanical properties. After the casting structure is deformed and recrystallized due to metal deformation after hot working of the forging method, the original coarse dendrite and columnar grains become equiaxed recrystallized grains with fine grain size and uniform size, so that the original segregation in the steel ingot is reduced. Loosening, porosity, slag inclusions and other compaction and welding, the organization becomes more compact, improving the metal's plasticity and mechanical properties.