00Cr27Mo3Ni2TiNb (S44660) is a steel tube developed by Ti+Nb dual stabilization method by reducing chromium content, increasing nickel content, and improving the plasticity, toughness, weldability, thermal stability, and hydrogen embrittlement resistance of the steel.
00Cr27Mo3Ni2TiNb, together with the aforementioned Cr29Mo4 (Ti, Nb) steel, is also one of the most famous super ferritic stainless steels currently used for heat transfer tubes of seawater condensers in power plants. The results of long-term application show that the performance of this steel is not only better than common stainless steels such as 304 and 316, but also better than copper alloys and copper-nickel alloys, and even comparable to titanium.
In terms of chemical composition, the addition of nickel can reduce the brittle transition temperature of steel, thereby improving the toughness of steel. In addition, the organizational characteristics of 00Cr27Mo3Ni2TiNb steel are the same as those of all super ferritic stainless steels, and the matrix organization of the steel adopts body-centered cubic ferrite organization. When heated at medium temperature (sensitization or welding heat affected zone), intermetallic compounds such as carbon, nitride, and σ will precipitate on the matrix, which will have an adverse effect on the performance of the steel.
The maximum value of the test temperature range refers to the maximum operating temperature allowed in the heat exchanger. If the temperature exceeds this value (i.e. >260°C), long-term use will lead to the precipitation of α' phase in the steel, which will cause the steel to become brittle at 475°C. Therefore, it is necessary to pay attention to the performance changes of the steel when using it for a long time under high temperature conditions.
Super stainless steel pipe
