第四类属超级双相不锈钢型，含高钼和氮，标准牌号UNS S32750（25Cr-7Ni-3.7Mo-0.3N）,有的也含钨和铜,PREN值大于40,可适用于苛刻的介质条件,具有良好的耐蚀与力学综合性 能，可与超级奥氏体不锈钢相媲美。国内外主要双相不锈钢牌号的近似对照见表2。
表1 双相不锈钢（DSS）代表牌号的主要化学成分和孔蚀抗力当量值
|
类别 |
标准 |
商业牌号 |
Chemical Analysis 化学成分1% |
孔蚀当量 |
|
Type |
Sandard |
Trademark |
C |
Cr |
Ni |
Mo |
N |
Cu |
W |
PREN |
PREW |
|
低合金型 |
UNS S32304 |
SAF2304 |
0.03 |
23 |
4 |
0.1 |
0.1 |
0.2 |
|
24 |
|
|
Low alloy |
W.Nr1.4362 |
UR 35N |
|
|
|
|
|
|
|
|
|
|
|
SS 2327 |
|
|
|
|
|
|
|
|
|
|
|
中合金型 |
UNS S31803 |
SAF2205 |
0.03 |
22 |
5 |
2.8 |
0.15 |
|
|
32/33 |
|
|
Middle alloy |
W.Nr1.4462 |
UR 45N |
|
|
|
|
|
|
|
|
|
|
|
SS 2377 |
|
|
|
|
|
|
|
|
|
|
|
|
|
UR45N+ |
0.03 |
22.8 |
6 |
3.3 |
0.18 |
|
|
35/36 |
|
|
|
UNS S31500 |
3RE60 |
0.03 |
18.5 |
5 |
2.7 |
0.1 |
|
|
29 |
|
|
|
WNr1.4417 |
A903 |
|
|
|
|
|
|
|
|
|
|
|
UNS S 32900 |
10RE51 |
0.08 |
25 |
4.5 |
1.5 |
|
|
|
30 |
|
|
|
W.Nr1.4460 |
|
|
|
|
|
|
|
|
|
|
|
|
SS 2324 |
|
|
|
|
|
|
|
|
|
|
|
|
AISI 329 |
|
|
|
|
|
|
|
|
|
|
|
|
|
UR50 |
0.06 |
21 |
7.5 |
2.5 |
|
1.5 |
|
29 |
|
|
|
UNS S32950 |
Carp7Mo+ |
0.03 |
27 |
4.8 |
1.75 |
0.25 |
|
|
35 |
|
|
高合金型 |
UNS S32550 |
Ferralium |
0.05 |
25 |
6 |
3 |
0.18 |
1.8 |
|
37 |
38 |
|
High alloy |
225 |
|
|
|
|
|
|
|
|
|
38 |
|
|
UNS S31250 |
DP3 |
0.03 |
25 |
7 |
3 |
0.16 |
0.5 |
|
37 |
|
|
|
|
UR47N |
0.03 |
25 |
6.5 |
3 |
0.22 |
|
|
38/39 |
|
|
|
W.Nr14507 |
UR52N |
0.03 |
25 |
6.5 |
3 |
0.17 |
1.5 |
|
38 |
|
|
|
|
VS25 |
0.03 |
25 |
6.5 |
3 |
0.18 |
|
|
38 |
|
|
超级DDS |
UNS S32760 |
Zeron100 |
0.03 |
25 |
7 |
3.5 |
0.24 |
0.7 |
0.7 |
40 |
41.5 |
|
super |
|
|
|
|
|
|
|
|
|
|
|
|
duplex |
|
|
|
|
|
|
|
|
|
|
|
|
stainless |
W.Nr1.4501 |
|
|
|
|
|
|
|
|
|
|
|
steel |
|
|
|
|
|
|
|
|
|
|
|
|
|
UNS S32750 |
SAF2507 |
0.03 |
25 |
7 |
3.8 |
0.28 |
|
|
41 |
|
|
|
W.Nr1.4410 |
UR47N+ |
|
|
|
|
|
|
|
|
|
|
|
SS 2328 |
|
|
|
|
|
|
|
|
|
|
|
|
UNS.S32550 |
UR52N+ |
0.03 |
25 |
7 |
3.5 |
0.25 |
1.5 |
|
41 |
|
|
|
W.Nr1.4507 |
|
|
|
|
|
|
|
|
|
|
|
|
UNS.S32740 |
DP3W |
0.03 |
7 |
3 |
0.27 |
|
2 |
39 |
42.5 |
|
