What’s the difference of duplex material S33205&S31803 ?

Duplex stainless steel is said to offer:
: Greater corrosion resistance, particularly against chloride stress corrosion and chloride pitting corrosion. Higher strength than typical austenitic stainless steels such as Type 304 or 316
.Compared to austenitic stainless steel, the most important changes are that duplex steels have greater resistance
chromium concentration.20-28 percent; a higher molybdenum content up to 5 percent; a lower nickel content up to 9 percent and 0.05-0.50 percent nitrogen
·Both the low nickel content and the high strength (allowing the use of thinner sections) offer significant advantages
savings measures
Applications of duplex stainless steel mainly take place in the two most important industries, i.e. H. in the offshore oil and gas sector for piping systems, manifolds, risers and other components; and in the petrochemical industry for pipelines and pressure vessels.

How is duplex stainless steel better than other stainless steels?

.Duplex steels offer higher strength compared to 300 series stainless steels in addition to better corrosion resistance
For example, 304 stainless steel has a 0.2 percent yield strength of about 280 N/mm2, while a 22 percent yield strength
Cr duplex stainless steel has a basic 0.2 percent yield strength of around 450 N/mm2 and a super duplex grade has a minimum of 550 N/m2
The minimum yield strength values ​​are almost twice as high as for austenitic stainless steel
.Because duplex grades allow for smaller cross-sections, they are attractive where mechanical properties allow temperature are required

What are the various grades of Duplex Stainless Steel?
Duplex stainless steels are often classified into three cateaories based on their resistance to pitting corrosion. as measured by the pittina resistance eauivalent number PREN=percent Cr+33 percent Mo + 16 percent N
Standard Duplex(PRENrange28-38)
Normally, EN 1.4462 is the grade(also called 2205).It is characteristic of mid-range houses and is maybe the most often used nowadays.
The super-duplex(PRENrange:38-45)
Usually,qrades EN 1.4410 and up to so-called hyper duplex grades(PREN:>45) were created subsequently to fulfill special needs of the oil and gas sectors.as well as the chemical industries.They have better corrosion resistance and strenath. but they are more difficult to process because areater levels of CrNiMoNand evenW stimulate the
production of intermetallic phases.which reduces the steel’s impact resistance sianificantly.Faulty processing will lead to poor performance. hence consumers should only work with recognized suppliers/processors.Deepwater offshore oi production is one of the applications.
Grades for leanduplexes(PRENrange22-27)
Grade EN 1 4362. for example.has recently been desianed for less demanding applicationsnotably in the buildina and construction sector.Their corrosion resistance is comparable to that of normal austenitic grade EN 1.4401 (with a little advantage in stress corrosion cracking resistance).and their mechanical qualities are superior.When strength is crucial this may be a huge benefit.This grade can be utilized for bridgespressure vessels and tie bars.
UNS S32205
UNS S32205 is ferritic-austenitic duplex steel having a ferritic-austenitic microstructure.In the annealed state, the alloy contains around 40-50 percent ferrite.
The duplex microstructure combines the touahness of ferritic arades with the corrosion resistance of austenitic arades. t is not unusual to see the metal emploved as a realistic answer to the Achilles’ heel of stainless steelchloride-induced stress cracking.
When compared to 317L stainless steel.UNS S32205 offers better resistance to chloride pitting and crevice corrosion. The alloy has excellent corrosion resistance to saltwater and most sulfuric acid concentrations.UNS S32205 duplex
stainless steel is also resistant to sulfide stress corrosion cracking(sour-gas environments).The large concentrations of chromium. nitrogen,and molybdenum contained in UNS S32205 are largely ascribed to its excellent composition and hence efficiency.

How are UNS 32205 and UNS 31803 different from each other?
The first standard for duplex stainless steel was preserved as UNS S31803.Howevera few of the industry’s major producers were routinely manufacturing this grade to the upper limit of the permissible standard.This mirrored thein intention to maximize the alloy’s corrosion performancewhich was supported by the invention of the AOD steelmakino process,which allowed for finer composition control.Furthermoreit enabled the degree of nitrogen additions to be reaulated rather than simply beina present as a background element.As a result.the best performina duplex grade tried to maximizechromium(cr)molybdenum(Mo)andnitrogenievels(N)
Anew standard.UNS S32205,was created to identify the duplex stainless steel produced at the upper end of the composition range.Duplex stainless steel manufactured to theS32205(F60)caption will completely meet the S31803(F51)caption but not the other way aroundAs a resultS32205 may also be dual-certified as S31803
WorkabilityS31803 and S32205
They have strona thermal strenath in the region of 9501150℃which is comparable to Type 430.However below 900°C it displays a significant rise in strength.Interms of cold workabilitycaution is required since proof stress is high and elongation is poor when compared toType304
Weldability Standards S31803 and S32205
TIG welding, shielded metal arc welding.and plasma welding may all be conducted in the same way as with normal austenitic stainless steelWeldina electrodes are recommendedThere is no need for preheatina or post-heatinaTo avoid the production of intermetallic.the interpass temperature in welding should not exceed 100°℃
Heat Treatment S31803 and S32205
Solution annealing should be carried out at temperatures of 1040℃ or abovefollowed by quenching in water or quick cooling by other methods.
Pickling S31803 and S32205
Picklina uses a combination of nitric acid and fiuoric acid.However.since descalina is more difficult than with Type 304 alkali immersion before acid pickling andif feasibleshot blasting is particularly effective

S31803 ysS32205:Which is better?
UNS S31803 and S32205 are alloyed with more similarities than differences.For starters,they are both stainiess steel with comparable elemental compositions.UNS S31803 and 32205 are both members of the duplex 2205 family,which implies they are approximately egually composed of austenite and ferriteSecond they are both very strong and long lasting alloys. s31803 and S32205 are both used in some of the most difficult and inhospitable manufacturing processes that need materials that can withstand repeated and continuous rides through the wringer
The most visible difference between the two is that UNS S32205 has a larer nitroaen concentration.which adds another laver of protection to an already firm surfaceThe presence of treated nitroaen provides an extra laver of protection aqainst any corrosive substances attempting to attack and eat away at the steel solution.This improved corrosion resistance offers UNS S32205 a minor but considerable advantage over its nearest competitor
The addition of nitrogen has increased its capacity to defend itselfwhich is the frostina on the cake