Duplex oteluri inoxidabile

Duplex oteluri inoxidabile

Typically twice the yield of austenitic stainless steels. De obicei de doua ori randamentul din otel inoxidabil austenitic. Minimum Specified UTS typically 680 to 750N/mm2 (98.6 to 108ksi). UTS minime specificate de obicei 680 750N/mm2 (98,6 la 108ksi). Elongation typically > 25%. Alungirea> de obicei 25%.

Superior corrosion resistance than a 316. Superior rezistenta la coroziune mult de un 316. Good Resistance to stress corrosion cracking in a chloride environment. Buna rezistenta la coroziune fisuranta intr-un mediu de clorura.

Duplex materials have improved over the last decade; further additions of Nitrogen have been made improving weldability. Duplex materiale s-au imbunatatit in ultimul deceniu; completarile ulterioare de azot au fost facute imbunatatirea sudabilitate.

Because of the complex nature of this material it is important that it is sourced from good quality steel mills and is properly solution annealed. Din cauza naturii complexe a acestui material este important ca acesta este provin de la fabricile de otel de buna calitate si este corect solutie recopt. Castings and possibly thick sections may not cool fast when annealed causing sigma and other deleterious phases to form. sectiunile turnate si, eventual, groase nu pot cool rapid atunci cand recoapte provoaca sigma si alte faze daunatoare pentru a forma.

The material work hardens if cold formed; even the strain produced from welding can work harden the material particularly in multi pass welding. Intareste material de lucru in cazul in formate la rece; chiar tulpina produse din sudare poate lucra intari materialul in special in sudare trece multi. Therefore a full solution anneal is advantageous, particularly if low service temperatures are foreseen. Prin urmare, o tempera solutie completa este avantajoasa, in special daca temperaturile scazute de serviciu sunt prevazute.

The high strength of this material can make joint fit up difficult. Concentratia ridicata a acestui material poate face potrivi comune pana dificil.

Usable temperature range restricted to, -50 to 280°C Gama de temperatura utila limitat la, -50 la 280 ° C

Used in Oil & Natural Gas production, chemical plants etc. Folosit in Oil & Gas Natural de productie, uzine chimice etc

Standard Duplex Standard Duplex
S31803 22Cr 5Ni 2.8Mo 0.15N PREn = 32-33 S31803 22Cr 5Ni 2.8Mo 0.15N prEN = 32-33

Super Duplex: Stronger and more corrosion resistant than standard duplex. Super Duplex: si mai rezistent la coroziune puternica decat duplex standard.
S32760(Zeron 100) 25Cr 7.5Ni 3.5Mo 0.23N PREn = 40 S32760 (Zeron 100) 25Cr 7.5Ni 3.5Mo 0.23N prEN = 40

Duplex solidifies initially as ferrite, then transforms on further cooling to a matrix of ferrite and austenite. Duplex solidifica initial ca ferita, apoi transforma pe mai departe de racire la o matrice de ferita si austenita. In modern raw material the balance should be 50/50 for optimum corrosion resistance, particularly resistance to stress corrosion cracking. In materii prime moderne, echilibrul ar trebui sa fie 50/50 pentru rezistenta la coroziune optim, in special rezistenta la coroziune fisuranta. However the materials strength is not significantly effected by the ferrite / austenite phase balance. Cu toate acestea, rezistenta materialelor nu este semnificativ efectuate de ferita / echilibrul faza austenita.

The main problem with Duplex is that it very easily forms brittle intermetalic phases, such as Sigma, Chi and Alpha Prime. Principala problema cu Duplex este ca foarte usor face faze fragil intermetalic, cum ar fi Sigma, Chi si prim-Alpha. These phases can form rapidly, typically 100 seconds at 900°C. Aceste faze pot forma rapid, de obicei, 100 secunde la 900 ° C. However shorter exposure has been known to cause a drop in toughness, this has been attribute to the formation of sigma on a microscopic scale. Cu toate acestea mai scurte de expunere a fost cunoscut de a provoca o scadere in tenacitate, acest lucru a fost atribut la formarea de sigma pe o scara microscopica.
Prolonged heating in the range 350 to 550°C can cause 475°C temper embrittlement. incalzire prelungita in intervalul 350 - 550 ° C poate provoca 475 ° C fragilizarea temperament.
For this reason the maximum recommended service temperature for duplex is about 280°C. Din acest motiv temperatura de serviciu maxima recomandata pentru duplex este de aproximativ 280 ° C.

Sigma (55Fe 45Cr) can be a major problem when welding thin walled small bore pipe made of super duplex, although it can occur in thicker sections. Sigma (55Fe 45Cr) poate fi o problema majora atunci cand sudura cu pereti subtiri diametru mic de conducte din duplex super, desi poate sa apara in sectiunile mai groase. It tends to be found in the bulk of the material rather than at the surface, therefore it probably has more effect on toughness than corrosion resistance. Ea tinde sa fi gasit in cea mai mare parte a materialului, mai degraba decat la suprafata, prin urmare, are efect, probabil, mai mult pe duritatea decat rezistenta la coroziune. Sigma can also occur in thick sections, such as castings that have not been properly solution annealed (Not cooled fast enough). Sigma poate aparea, de asemenea, in sectiunile groase, cum ar fi turnate, care nu au fost corect solutie recopt (Nu este racit suficient de repede).

However most standards accept that deleterious phases, such as sigma, chi and laves, may be tolerated if the strength and corrosion resistance are satisfactory. Cu toate acestea majoritatea standardelor accepta ca fazele nocive, cum ar fi sigma, chi si laves, poate fi tolerata in cazul in care puterea si rezistenta la coroziune sunt satisfacatoare.

Nitrogen is a strong austenite former and largely responsible for the balance between ferrite and austenite phases and the materials superior corrosion resistance. Azotul este un puternic austenita fost si in mare parte responsabile pentru echilibru intre fazele ferita si austenita si materiale de rezistenta superioara la coroziune. Nitrogen can't be added to filler metal, as it does not transfer across the arc. De azot nu poate fi adaugat la metal de adaos, deoarece nu se transfera in arc. It can also be lost from molten parent metal during welding. Acesta poate fi, de asemenea, pierdut de la mama metal topit in timpul sudarii. Its loss can lead to high ferrite and reduced corrosion resistance. Pierderea lui poate duce la ferita de inalta si rezistenta redusa la coroziune. Nitrogen can be added to the shielding gas and backing gas, Up to about 10%; however this makes welding difficult as it can cause porosity and contamination of the Tungsten electrode unless the correct welding technique is used. Azot pot fi adaugate la gaz gaz de protectie si suport, pana la aproximativ 10%, insa acest lucru face dificila de sudura, deoarece poate provoca porozitatea si contaminarea Tungsten electrodului exceptia cazului in care tehnica de sudare este folosit corect. Too much Nitrogen will form a layer of Austenite on the weld surface. Prea mult azot vor forma un strat de austenitic pe suprafata sudura. In my experience most duplex and super duplex are TIG welded using pure argon. In experienta mea cea mai duplex si duplex super TIG sunt sudate cu argon pura.

Backing / purge gas should contain less than 25ppm Oxygen for optimum corrosion resistance. Suport / gazul de purjare trebuie sa contina mai putin de 25 ppm de oxigen pentru rezistenta la coroziune optim.

Fast cooling from molten will promote the formation of ferrite, slow cooling will promote austenite. Racire rapida de la topit va promova formarea de ferita, racire lenta va promova austenita. During welding fast cooling is most likely, therefore welding consumables usually contain up to 2 - 4% extra Nickel to promote austenite formation in the weld. In timpul de racire rapida de sudare este cel mai probabil, prin urmare, consumabile de sudura, de obicei, contine pana la 2-4% in plus cu nichel pentru a promova formarea austenita in sudura. Duplex should never be welded without filler metal, as this will promote excessive ferrite, unless the welded component is solution annealed. Duplex nu ar trebui sa fie sudate fara metal de adaos, deoarece aceasta va promova ferita excesive, cu exceptia cazului in componenta sudate este solutia recopt. Acceptable phase balance is usually 30 - 70% Ferrite echilibru acceptabil faza este, de obicei 30 - 70% ferita

Duplex welding consumables are suitable for joining duplex to austenitic stainless steel or carbon steel; they can also be used for corrosion resistant overlays. Duplex consumabile de sudura sunt potrivite pentru aderarea duplex din otel inoxidabil austenitic sau din otel carbon; ele pot fi de asemenea utilizat pentru rezistent la coroziune suprapuneri. Nickel based welding consumables can be used but the weld strength will not be as good as the parent metal, particularly on super duplex. Bazate pe nichel consumabile de sudura poate fi utilizat, dar puterea sudura nu va fi la fel de bun ca metalul de baza, in special pe duplex super.

• Low levels of austenite: - Poor toughness and general corrosion resistance. Nivelurile scazute de austenita: - Poor duritatea si rezistenta la coroziune general.

• High levels of austenite: - Some Reduction in strength and reduced resistance to stress corrosion cracking. Nivelurile ridicate de austenita: - o reducere in forta si rezistenta redusa la coroziune fisuranta.

Good impact test results are a good indication that the material has been successfully welded. Rezultatele bune test de impact sunt un bun indiciu ca materialul a fost cu succes sudate. The parent metal usually exceeds 200J. Metal-mama, de obicei, mai mare de 200J. The ductile to brittle transition temperature is about -50°C. Ductil la temperatura de tranzitie fragil este de aproximativ -50 ° C. The transition is not as steep as that of carbon steel and depends on the welding process used. Tranzitia nu este la fel de abrupt ca din otel carbon si depinde de procesul de sudare utilizate. Flux protected processes, such as MMA; tend to have a steeper transition curve and lower toughness. Flux protejate procese, cum ar fi AMM; tind sa aiba o curba de tranzitie mai abrupta si tenacitate mai mici. Multi run welds tend to promote austenite and thus exhibit higher toughness Multi suduri alerga tind sa promoveze austenita si, astfel, prezinta duritate mai mare

Tight controls and the use of arc monitors are recommended during welding and automatic or mechanised welding is preferred. controale stricte si utilizarea de monitoare arc sunt recomandate in timpul sudarii si automate de sudat sau mecanizata este de preferat. Repair welding can seriously affect corrosion resistance and toughness; therefore any repairs should follow specially developed procedures. sudura de reparare poate afecta serios rezistenta la coroziune si tenacitate; prin urmare, orice reparatii ar trebui sa urmeze procedurile special dezvoltate. See BS4515 Part 2 for details. A se vedea BS4515 Partea 2 pentru detalii.

Production control test plates are recommended for all critical poduction welds. Productia de placi de test de control sunt recomandate pentru toate suduri poduction critice.

Welding procedures should be supplemented by additional tests, depending on the application and the requirements of any application code:- Procedurile de sudare ar trebui sa fie completate cu teste suplimentare, in functie de aplicatie si cerintele oricarei codul aplicatiei: -

• A ferrite count using a Ferro scope is probably the most popular. Un numar de ferita folosind un domeniu de aplicare Ferro este, probabil, cele mai populare. For best accuracy the ferrite count should be performed manually and include a check for deleterious phases. Pentru cele mai bune precizie numarul de ferita ar trebui sa fie efectuate manual si sa includa un cec in fazele de daunatoare.

• Good impact test results are also a good indication of a successful welding procedure and are mandatory in BS4515 Part 2. Rezultatele bune test de impact sunt, de asemenea, un bun indicator al unei proceduri de sudare de succes si sunt obligatorii in BS4515 partea 2.

• A corrosion test, such as the G48 test, is highly recommended. Un test de coroziune, cum ar fi testul G48, este foarte recomandat. The test may not model the exact service corrosion environment, but gives a good qualative assessment of the welds general corrosion resistance; this gives a good indication that the welding method is satisfactory. Testul nu poate model mediu de servicii exact coroziune, dar ofera o evaluare buna qualative a rezistentei la coroziune sudurilor general, acest lucru da o indicatie bine ca metoda de sudura este satisfacatoare. G48 test temperature for standard duplex is typically 22°C , for super duplex 35°C G48 temperatura de testare pentru duplex standard este de obicei 22 ° C, pentru duplex super 35 ° C

Typical Welding Procedure For Zeron 100 (Super Duplex) Procedura de sudare tipic pentru Zeron 100 (Duplex Super)

Pipe 60mm Od x 4mm Thick Position 6G Conducta de 60mm x 4mm Od 6G gros Pozitia

Maximum Interpass 100°C Temperature at the end of welding < 250°C Maxim Interpass 100 ° C Temperatura la sfarsitul sudare <250 ° C

1.6mm Filler Wire 85 amps 2 weld runs (Root and Cap) 1.6mm Filler Wire 85 Amperi 2 ruleaza sudura (Root si Cap)

Arc energy 1 to 1,5 KJ/mm Travel speed 0.75 to 1 mm/sec Arc de energie de la 1 la 1,5 KJ / mm Viteza de deplasare 0.75-1 mm / sec

Recommended Testing Recomandat de testare

1. Ferric Chloride Pitting Test To ASTM G48 : Method A Ferice de testare Coroziune prin puncte de clorura de ASTM G48: Metoda A
2. Chemical analysis of root Analiza chimica a radacina
3. Ferrite count Ferita conta

https://www.gowelding.com/met/duplex.html