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Duplex 2205 (S31803) PALL RING
2205 has been available for several years - in general this complies with UNS grade designation S31803. More recently, product has become available complying with the higher corrosion resistant composition UNS S32205, as in table 1. Both these alternatives are known as 2205.
Composition
Grade 2205 has a micro structure of roughly equal amounts of ferrite and austenite, hence the 'duplex' description. The duplex structure of 2205 has the following properties:
- High strength.
- Lower thermal expansion co-effecient than austenitic steels but greater than carbon steels.
- High resistance to corrosion, particularly stress corrosion cracking, corrosion fatigue and erosion.
The high content of chromium and molybdenum and the addition of nitrogen gives the steel further beneficial characteristics:
- High general corrosion resistance.
- High pitting and crevice corrosion resistance.
- Good sulphide stress corrosion cracking resistance.
The addition of nitrogen gives a further increase in pitting and crevice corrosion resistance.
|
Table 1: Composition of 2205 and Alternative Grades (Single Values are Maximum)
|
| Grade |
Common Name |
C% |
Mn% |
Si% |
P% |
S% |
Cr% |
Ni% |
Mo% |
N% |
| S31803 |
2205 |
0.030 |
2.00 |
1.00 |
0.030 |
0.020 |
21.0-23.0 |
4.5-6.5 |
2.5-3.5 |
0.08-0.20 |
| S32205 |
2205 |
0.030 |
2.00 |
1.00 |
0.030 |
0.020 |
22.0-23.0 |
4.5-6.5 |
3.0-3.5 |
0.14-0.20 |
Corrosion Resistance
The grade has excellent corrosion resistance and is superior to grade 316, performing well in most environments where standard austenitic grades may fail. 2205's low carbon content gives the grade a high resistance to intergranular corrosion and has better resistance to uniform, pitting and crevice corrosion due to its high chromium and molybdenum content.
As 2205 is a duplex stainless steel, the grade is also less sensitive to stress corrosion cracking in warm chloride environments, unlike austenitic stainless steels. The grade also has good resistance to stress corrosion cracking when exposed to hydrogen sulphide in chloride solutions.
High mechanical strength combined with excellent corrosion resistance gives 2205 high corrosion fatigue resistance.
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Grade
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Reasons for choosing grade 904L
|
|
316L
|
A lower cost alternative, but with much lower corrosion resistance.
|
|
6Mo
|
A higher resistance to pitting and crevice corrosion is needed.
|
|
2205
|
A very similar corrosion resistance, with the 2205 having higher mechanical strength, and at a lower cost to 904L. (2205 not suitable for temperatures above 300°C.)
|
|
Super duplex
|
Higher corrosion resistance is needed, together with a higher strength than 904L.
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Metal Pall ring Spec.( steel), Carbon steel, SS304, SS316, SS304L, SS316L, etc.
| Model NO. |
Spec. D×H×δ
mm |
Specific surface α
m2/m3 |
Void ratio ε
% |
Piling NO. n
m-3 |
Piling Weight γρ
kg/m3 |
Dry filler factor F
m-1 |
| Dg16 |
16×16×0.5 |
311 |
0.93 |
244000 |
539 |
455 |
| Dg25 |
25×25×0.6 |
233 |
0.937 |
64000 |
489 |
252 |
| Dg38 |
38×38×0.8 |
129 |
0.945 |
18220 |
432 |
153 |
| Dg50 |
50×50×1.0 |
112.3 |
0.949 |
8000 |
395 |
131 |
| Dg76 |
76×76×1.5 |
70 |
0.952 |
2270 |
374 |
81 |
Duplex 2205是一种氮增强型双相不锈钢，用于解决300系列不锈钢遇到的常见腐蚀问题。“Duplex”描述了一系列不锈钢，既不是完全奥氏体，也不是304不锈钢，也不是纯铁素体，如430不锈钢。2205双相不锈钢的结构由奥氏体池组成，周围是连续的铁素体相。在退火状态下，2205含有约40-50％的铁素体。通常被称为工作马等级，2205是双相不锈钢系列中使用最广泛的等级。
双相结构的优点在于它将铁素体合金的优良品质（抗应力腐蚀开裂性和高强度）与奥氏体合金的优良品质（易于制造和耐腐蚀性）相结合。
2205双相不锈钢的使用应限制在600°F以下。延长的高温暴露会使2205不锈钢变脆。
Duplex 2205化学成分
|
Cr
|
Ni
|
Mo
|
C
|
N
|
Mn
|
Si
|
P
|
S
|
|
22.0-23.0
|
4.50-6.50
|
3.00-3.50
|
.030 Max
|
0.14-0.20
|
2.00 Max
|
1.00 Max
|
.030 Max
|
.020 Max
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Duplex 2205性能
|
区分
|
力学性能
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备注
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|
|
|
Ys (Mpa)
|
Ts (Mpa)
|
El (%)
|
Hv
|
2.0t/2B
|
|
标准
|
≥ 450
|
≥ 620
|
≥ 18
|
≤ 320
|
|
一般
|
670
|
875
|
27
|
280
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Duplex 2205物理性能
|
密度
(g/cm)
|
磁性
|
比热
(J/g.C)
|
热导率
100C(W/m.
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热膨胀率
20~100C
(10/C)
|
|
7.8
|
有
|
0.45
|
19.0
|
13.7
|
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