F44 super stainless steel (marketing department of Shanghai HY Industry Co., Ltd)
F44 is the patented steel number of Avesta Company of Sweden (acquired by Outokumpu in 2001) in 1978, which belongs to 6Mo type super austenitic stainless steel. This kind of steel has extremely high corrosion resistance (better than 904L), and is usually used in seawater desalination and chemical engineering.
Super stainless steel is a stainless steel between ordinary stainless steel and nickel-based alloys. It is specially invented to deal with severe corrosion conditions that ordinary austenitic stainless steel cannot handle (such as high-concentration chloride ion medium or seawater and other environments).
The composition of super stainless steel is characterized by high Cr and high Ni (or high Mo). The content of Cr or Ni is generally 18-26%, the content of Mo is 4-8%, and the pitting equivalent PREN is greater than 40 (or even greater than 42).
This kind of super stainless steel with a PRE equivalent greater than 42 is also called 6Mo stainless steel. Common 6Mo stainless steels include AL-6XN, 654 SMO, 1925 hMo and 25-6Mo. The composition of 254 SMO and AL-6XN is very similar, and they are often compared. The significant difference between the two is the difference in nickel content, and 254 SMO is about 6% lower.
Among 6Mo stainless steels, 254 SMO is the most cost-effective steel grade, but its poor processing performance limits its application to some extent.
chemical composition & Standard（wt%）
Standard |
Outokumpu |
ASTM A182 |
DIN EN 10088-3-2005 |
Grade |
254 SMO |
F44S31254 |
X1CrNiMoN20-18-71.4547 |
C |
≤0.020 |
≤0.020 |
|
Si |
≤0.80 |
≤0.70 |
|
Mn |
≤1.00 |
≤1.00 |
|
P |
≤0.030 |
≤0.030 |
|
S |
≤0.010 |
≤0.010 |
|
Cr |
19.5~20.5 |
19.5~20.5 |
|
Ni |
17.5~18.5 |
17.5~18.5 |
|
Mo |
6.0~6.5 |
6.0~7.0 |
|
Cu |
0.5~1.0 |
0.5~1.0 |
|
N |
0.18~0.22 |
0.18~0.25 |
|
Mechanical properties
Rm （MPa） |
Rp0.2 (MPa） |
A% |
Z% |
≥650 |
≥300 |
≥35 |
≥50 |
