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James Alloys can now offer a complete range of Lean Duplex products
James Alloys and our dedicated partners are delighted to announce the introduction of a complete new range of ”LEAN DUPLEX” products.
We can now supply “LEAN DUPLEX” in all forms from round, flat bars, sheets, plates, square tubes, rectangular tubes plus a wide range of sections including channels, angles T sections, beams and even wire products for more specific details on our products please visit our products page
In addition to the supply of the raw material we can also offer a full semi fabrication service with the material where we can laser cut, etch, fold or machine the material prior to delivery, for further information of our fabrication services please visit our fabrication page
Introduction
Stainless steels are used predominantly for their corrosion resistance in moderate to highly aggressive environments. For construction purposes, carbon steel normally is the common choice due to low cost, long experience, applicable design rules and a large variety of strength classes. However, different stainless steel types can also provide a very wide range of mechanical properties and they have the advantage of no need for surface protection. Duplex stainless steels in particular, with twice the mechanical strength of conventional austenitic and ferritic stainless steels, have a potential for use in constructions. Since the introduction of this family of steels about seventy years ago, they have been widely used.
Lean Duplex Stainless Steels (LDSS) are a subset of the duplex family that has seen significant growth and development over the last years. The drivers for this development have been soaring raw material costs along with increasing demand for improved corrosion resistance and strength. Today there are four different LDSS grades available on the market and new ones are being developed.
LDSS have been used or are being considered as substitutes for stainless steel types 1.4301 and 1.4404 in various applications. Some examples of industry end users are structural supports for the onshore and offshore oil & gas industry, architectural & building, desalination equipment, wastewater treatment facilities, pulp & paper, chemical processing, automotive & transportation, etc. The list keeps growing as more industries become aware of the advantages of LDSS
Corrosion aspects
LDSS' resistance to localized corrosion, such as pitting and crevice attack, is similar to type 1.4404 or 1.4571. A numerical relationship between pitting resistance and alloying content has been developed to compare the four LDSS to common austenic stainless steels (Fig.1). This numerical relationship is known as pitting resistance equivalent number or PREN (PREN = Cr + 3.3 x %Mo + 16 x %N).
Pitting and crevice corrosion resistance
|
PREN |
|||||||||||
| EN | Type equivalent |
C | Si | Mn | P | S | Cr | Ni | Mo | N | ||
max |
|
|
|
|
||||||||
1.4301 |
304 |
0,07 |
1,0 |
2,0 |
0,045 |
0,030 |
17,0-19,5 |
8,0-10,5 |
--- |
≤ 0,11 |
||
1.4404 |
316L |
0,03 |
1,0 |
2,0 |
0,045 |
0,030 |
16,5-18,5 |
10,0-13,0 |
2,0-2,5 |
≤ 0,11 |
||
- |
2001 |
0,03 |
1,0 |
4,0-6,0 |
0,040 |
0,030 |
19,5-21,5 |
1,0-3,0 |
0,1-0,6 |
0,05-0,17 |
||
1.4162 |
2101 |
0,04 |
1,0 |
4,0-6,0 |
0,040 |
0,030 |
21,0-22,0 |
1,35-1,7 |
0,1-0,8 |
0,20-0,25 |
||
1.4362 |
2304 |
0,03 |
1,0 |
2,0 |
0,035 |
0,015 |
22,0-24,0 |
3,5-5,5 |
0,1-0,6 |
0,05-0,20 |
||
- |
2003 |
0,03 |
1,0 |
2,0 |
0,030 |
0,020 |
19,5-22,5 |
3,0-4,0 |
1,5-2,0 |
0,14-0,20 |
||
1.4462 |
2205 |
0,03 |
1,0 |
2,0 |
0,035 |
0,015 |
21,0-23,0 |
4,5-6,5 |
2,5-3,5 |
0,10-0,22 |
||
LDSS are “leaner” alloys than the standard type 1.4462 duplex stainless steel and cannot equal its corrosion resistance, especially in high chloride environments, but they have a much better resistance than 1.4301 and in most cases perform as well as, or better then 1.4404. As a result, LDSS are suitable for use in a wide range of applications and environments.
Advantages – Lean Duplex Stainless
● Corrosion Fatigue Resistance
● Up To 3 Times The Strength Of Type 316L
● Improved Mach inability
● High Energy Absorption
● Low Thermal Expansion
● Stress Corrosion Cracking (SCC)* Resistance
● Pitting Resistance
● Crevice Corrosion Cracking Resistance
● Intercrystalline Corrosion Resistance
● Erosion/Corrosion Resistance
Conclusions
Material selection is a more important consideration than ever before because of project planning difficulties resulting from raw material surcharge volatility. Switching to innovative alloys like LDSS offers economic value in terms of reduced raw material surcharge as well as improved mechanical properties.
Structural sections like beams, channels and angles made of LDSS achieve equivalent performance at a lower cost. The high performing structural sections satisfy the needs of the engineers and designers for light, innovative and cost-effective structures in stainless steel which at the same time fulfil the criteria of safety and durability.
