1. The meaning of super stainless steel
At the end of the 20th century, stainless steel "super" grades were produced at home and abroad. Different documents on super stainless
The definition of steel is different. Some literatures suggest that high-performance stainless steel is also called super-stainless steel; some literature believes that
High-alloy stainless steel is called super-stainless steel; some literatures believe that: super-stainless steel also includes high-performance,
Special requirements for some low-alloy stainless steels, such as Super 304H chrome-nickel austenitic stainless steel;
According to the literature, super stainless steel refers to pitting resistance equivalent PREN value ≥ 35 (ferritic stainless steel) or ≥ 40 (the Austrian
High-alloyed high-performance stainless steel of stainless steel and duplex stainless steel; some literature further believes that super
Grade stainless steel should also include ultra-high cleanliness, ultra-high uniformity, ultra-fine structure, extra-high surface quality, and excellent
Resistance to harsh localized local corrosion properties, good process manufacturing performance, etc.
2, the common characteristics of super stainless steel
■ It has a finer special component design than the four types of stainless steel;
■ has a high degree of clarity;
■Excellent uniformity (ingredients, organization and properties);
■Excellent performance in more demanding environments than four types of stainless steel;
■ Has good process manufacturing performance;
■ has a high cost performance;
3. Definition of super stainless steel
■Super stainless steel is one of the stainless steels, one of the iron-based alloys with a Cr content of 12-30%.
Super stainless steel must contain more than 12% of Cr, but the Cr content is usually ≤ 30%;
■Super stainless steel is not an iron-nickel-based corrosion-resistant alloy, because the Ni-based corrosion-resistant alloy contains >30% of Ni,
Ni+Fe≥50%; therefore, for Ni-containing super stainless steel, the Ni content must be ≤30%;
■Super stainless steel must have better performance in harsh environments, such as local corrosion resistance such as pitting corrosion
Energy, characterized by pitting resistance equivalent PREN = % Cr + 3.3 (% Mo) + 16 (% N). Usually super austenitic stainless steel
The PREN of super duplex stainless steel should be ≥40, and the PREN of super ferritic stainless steel should be ≥35.
Super stainless steel for special use requirements must have an abnormal breakthrough in the weak link of key performance.
For example, super martensitic stainless steel must be weldable "soft martensitic stainless steel"; super high temperature austenite is not
Stainless steel must break through the creep problem of 600 ° C or more and 300 bar stress.