In the production of 304 stainless steel pipes, not only the production cost, but also the factors of preventing corrosion and improving product quality must be considered, so solution treatment is adopted in the production process. However, some 304 stainless steel pipe manufacturers will perform another stabilization treatment after the 304 pipe solution treatment. So, why should the 304 stainless steel pipe be stabilized? Next, stainless steel pipe manufacturer Huiyingsteel will take you to explore them one by one.

Definition of Stabilization Treatment of Stainless Steel pipes

Stabilization treatment is also called homogenization treatment, which is for austenitic stainless steel pipes containing titanium or niobium. For 304 stainless steel pipes, there are usually four situations to be stabilized.

Stainless steel pipe needs to be stabilized

The first is the welded pipe with strict requirements for resistance to intergranular corrosion; the second is to use under high temperature (above 350 ℃) conditions; the third is to inspect the unqualified products of the intergranular corrosion test through the sample; the fourth is to carry out large-area repair welding.

Stabilization treatment points of stainless steel pipe

For customers, intergranular corrosion of 304 stainless steel pipes is their greatest concern. Therefore, at this time, the 304 stainless steel pipe with strict requirements on intergranular corrosion needs to be stabilized again after the solution treatment. Adding titanium or niobium to the 18-8 stainless steel tube can eliminate intergranular corrosion, but it is impossible to eliminate it completely.

Because when the content of titanium or niobium is insufficient, there will be some excess carbon and chromium to form chromium carbide, even if the content of titanium or niobium is acceptable. However, due to the presence of a large amount of titanium nitride impurities in the 304 stainless steel pipe, the effective titanium content will still be reduced.

The heating temperature of the stabilized 304 stainless steel pipe should be higher than the temperature at which the chromium carbide is completely dissolved and lower than the temperature at which the titanium carbide or niobium carbide is completely dissolved so that the chromium carbide is completely dissolved, and the titanium carbide or niobium carbide is partially retained.

It is then cooled slowly so that the part of the titanium carbide or niobium carbide that dissolves in the austenite when heated can be fully precipitated during the cooling process. In this way, the carbon is almost completely stabilized in titanium carbide or niobium carbide.

After the 304 stainless steel pipe is treated in this way, the chromium carbide will not be precipitated again, the chromium content in the solid solution can be retained, and the 304 stainless steel pipe will not have the tendency of intergranular corrosion. The temperature of stabilization treatment is usually between 880 and 950°C, and the temperature is kept for 5 to 6 hours. The cooling method can be cooling in air or cooling in a furnace.

Well, I hope that the introduction of the above content can help you better understand the stabilization treatment of stainless steel pipes, and help you learn more about stainless steel pipes. If you want to get more information about stainless steel pipes, you can check our previous highlights:

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