The stainless steel heat exchange tube is one of the heat exchange elements of the heat exchanger. The quality and performance characteristics of the heat exchange tube will affect the heat exchange work and efficiency. Therefore, in order to make better use of the heat exchange tubes, the heat exchange tubes need to be carefully selected and handled correctly. The treatment of stainless steel heat exchange tubes mainly includes heat treatment, grinding treatment, pickling passivation and so on. Among them, heat treatment is particularly important.
So how is the heat treatment of stainless steel heat exchange tubes done?
By changing the structure of the stainless steel tube through heat treatment, the processing performance can be changed. For example, the 304 stainless steel heat exchange tube has a low carbon mass fraction, even if normalizing is used, it is difficult to achieve the required surface roughness of the gear shaper and reduce the tool life. Instead, low-carbon martensite and iron cord structure are obtained after incomplete quenching, which improves the hardness. Not only the surface roughness meets the requirements, but the service life of the stainless steel heat exchange tube is also increased by 3 to 4 times, so in order to better use the stainless steel heat exchange tube, it needs to be heat treated.
Therefore, proper selection of heat treatment process can effectively improve the grinding performance of steel, such as strictly controlling the mass fraction of carbon in the carburized layer (not exceeding W=1.10%) and eliminating network carbides. The protective gas non-oxidizing continuous heat treatment furnace is widely used in the heat treatment of stainless steel heat exchange tubes abroad, and can be used for intermediate and final heat treatment of the finished product during the production process. Because a bright surface without oxidation can be obtained, the traditional pickling process is eliminated. The use of this heat treatment process not only improves the quality of steel pipes, but also overcomes environmental pollution caused by pickling.
Note: Seamless heat exchanger tubes: ASTM A179 Standard require minimum-wall thickness, seamless cold-drawn low-carbon steel tubes for tubular heat exchangers, condensers, and similar heat transfer apparatus.