How to Weld Type 2205 Code Plus T wo ®Duplex Stainless Steel
Outokumpu Stainless
Material Description
2205 is a duplex (austenitic-ferritic) stainless steel that combines many of the best properties of austenitic and ferritic stainless steels. High chromium and molybdenum contents provide excellent resistance to pitting and crevice corrosion. The duplex structure is highly resistant to chloride stress corrosion cracking. 2205 has outstanding strength and toughness and posss good weldability.
The trademark Code Plus T wo ®indicates the commitment, not only to meet the requirements for S31803 as established in ASTM and ASME,but also to meet two additional requirements. The first requirement was that nitrogen should be in the 0.14 to 0.20% range to gain its benefits in higher strength, higher corrosion resistance, greater metallurgical stability, and superior properties after welding. The cond requirement was that all mill products should pass a test for the abnce of detrimental intermetallic phas. The tests
developed by Outokumpu Stainless for this purpo have been formalized as the ASTM A 923 standard test method.
The special requirements now define a new quality of 2205, designated S32205. S32205 is dual certifiable as S31803, but reprents what urs have come to expect of 2205 steel. Both S31803 and S32205 are included in all applicable ASTM product specifications.
The incread strength of S32205, relative to that of S31803, resulting from its higher nitrogen is now being recognized by ASTM and ASME. The ASTM has designated S32205 as 2205.
Forming, Heat Treatment, and Machining Hot Forming
2205 is hot formed in the range 2250–1750°F (1230–955°C). In this range, the material has low mechanical strength and good hot ductility. If slow cooled or held at temperatures between 600 and 1750°F (315–955°C), the combination of strain and temperature can lead to rapid room temperature embrittlement by the formation of sigma pha and other detrimental intermetallic compounds.Full annealing with rapid cooling, ideally water quenching, is recommended after hot forming.
Cold Forming
Becau of its higher strength, 2205 requires higher forces for cold forming than tho typical for austenitic stainless steels. Additional allowance for springback is necessary. Outokumpu Stainless 2
205may be formed on equipment typically ud for forming austenitic stainless steels, once allowance has been made for its higher strength. Designs with 2205 frequently have ud its higher strength to permit reductions of gauge, significantly easing many forming applications. Full annealing and
quenching is recommended after vere cold forming.
Heat Treatment
2205 is annealed at 1900°F (1040°C) minimum with subquent rapid cooling, ideally water
UNS S32205, S31803 (wrought products)UNS S39209 (bare welding wire)UNS J92205 (cast products)ASTM
ASME阅读答案网
Plate, Sheet, Strip A 240, A 480SA-240, SA-480Bar, Billet A 276, A 479
SA-479
辅料英文Pipe, Tubing A 789, A 790, A 928SA-789, SA-790Forgings, Fittings A 182, A 815SA-182, SA-815
英语小知识
Castings A 890Testing
A 923
ASME Code Ca 2186 (Embosd Asmblies)ASME/ANSI B16.34 for A 182, A 240, A 479, A 789, A 790ASME/ANSI B16.5, ASME/ANSI B31.1 Code Ca 153ASME/SFA 5.4, SFA 5.9, and SFA 5.22 P No. 10H, Group 1AWS/A5.4 E 2209-XX, A5.9 ER 2209, A5.22 E 2209T0-X NACE MR0175
Specifications
Type 2205 Code Plus Two® Duplex Stainless Steel 2acquire怎么读
quenching. This treatment applies for both full solution annealing and stress-relief annealing. Machining
2205 may be machined with high-speed steel tooling at the same speeds and feeds as Type 316L austenitic stainless steel. With carbide tooling, positive rake angle, and C-5 and C-6 grades for roughing and finishing, respectively, should be ud. Cutting speeds should be reduced by about 20% from tho typical for Type 316L. The high strength of 2205 requires powerful machines and exceptionally strong and rigid tool mounting. Welding–General Guidelines
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The goal in welding any duplex stainless steel is to obtain fusion and heat-affected zones having the excellent corrosion resistance of the ba metal and sufficiently high impact toughness for the application. 2205 Code Plus T wo®ba metal
has an annealed structure with ferrite content in the range of 30–55%, and is virtually free of intermetallic phas. Welding procedures should be designed to produce this same structure in the weld metal and heat-affected zones. The weld thermal cycle, as well as filler metal and protection atmosphere, will control this structure. Near the fusion temperature, the structure of duplex stainless steels is entirely ferrite. The desired 30–55% ferrite can be achieved only if the cooling rate is slow enough to allow austenite to re-form as the weld cools. If the cooling rate is too slow, however, embrittling intermetallic phas may form in spite of the prence of the optimum ferrite content. Extremely low heat input followed by rapid cooling will produce a predominantly ferritic heat-affected zone with reduced toughness and corrosion resistance. This might occur with a GTAW wash pass or resistance spot welding. On the other hand, excessive time in the 1300–1800°F (705–980°C) range can lead to formation of intermetallic phas having a similar detrimental effect on properties.
Outokumpu Stainless 2205 Code Plus T wo has been produced to assist the welder. One important feature is that 2205 Code Plus T wo has 0.14–0.20% nitrogen, compared to the 0.08–0.20% nitrogen
permitted by ASTM and ASME. This higher nitrogen helps austenite re-form quickly during cooling so that the weld and heat-affected zone
are more easily converted back to the optimal austenitic-ferritic balance. In addition, special quality assurance procedures combined with the higher nitrogen content make 2205 Code Plus T wo more resistant to formation of intermetallic phas. Avesta Welding Products 2205 filler metals, typically designated as 2209, are more highly alloyed with nickel relative to the ba metal to assure a fusion zone with austenite-ferrite balance,toughness, and corrosion resistance similar to tho of the ba metal. With Outokumpu Stainless 2205 ba metal and filler, the welder has a workable range of operating conditions. By following the guidelines provided in properly qualified procedures,the welder can produce economical constructions with consistent, high-quality welds.
Control of Intermetallic Phas
2205 duplex stainless steel can experience
veral precipitation reactions. The intermetallic compound, sigma pha, can precipitate between 1300–1800°F (705–980°C). Carbides can
Figure 1 Time—Temperature Precipitation Diagram
Type 2205 Code Plus Two® Duplex Stainless Steel3
precipitate between 800–1500°F (425–815°C), and “885 (425°C) embrittlement” can occur in
the temperature range of 650–950°F (340–510°C). If 2205 is held for sufficiently long times in any of
the temperature ranges, precipitation reactions will occur. The formation of precipitates can embrittle 2205, reducing its ambient temperature ductility and toughness, and can reduce its corrosion resistance. The rate of the precipitation reactions is dependent on the chemical composition of 2205 and other metallurgical factors. Figure 1 shows a Time-Temperature-Precipitation curve for a 2.25 inch (57 mm) thick 2205 plate with 0.14% nitrogen. The curve corresponds to an ambient temperature impact toughness of 20 ft.-lb. (27J). Time-temperature combinations to the right of the curve have less than 20 ft.-lb. of toughness.罢黜
Low Temperature Impact Tests
Low temperature impact testing may be required by the ASME code (e.g., Section VIII Div. 1 UHA-51), by a customer specification, or a requirement to meet ASTM A 923 Method B, which calls for a single impact test at -40ºF (-40ºC). Many factors may adverly affect the low temperature impact properties of welds, e.g., elevated ferrite content, prence of deleterious phas, and elevated oxygen content. The latter is a factor in welding process that u a flux, and is affected by the type of flux. Welds may not meet the minimum requirements of A 923 Method B, becau the acceptance criteria were established for solution annealed plate, but that does not necessarily mean detrimental intermetallic phas are prent. As a general guideline, it is possible to arrange the wel
ding process in order of increasing impact toughness as follows: SMAW-rutile coating; FCAW; SMAW-basic coating; SAW, GMAW, GTAW. Outokumpu Stainless is willing to assist in choosing the proper welding consumable for the procedure qualifications bad on
test temperature.
Pitting Test
The standard pitting test ud on 2205 is ASTM A 923 Method C. Prior to the creation of A 923, the pitting test was often referred to as “ASTM G 48 Practice B modified.” T esting is done in a ferric chloride solution at a specific temperature, 25ºC for ba material and 22ºC for annealed welds for 24 hours. Other temperatures may be t by customer specifications, sometimes with minor variations to the test method. The performance of welds in this solution may have no correlation to corrosion performance in other media and is not intended as a fitness for rvice test in any specific rvice environment. As with impact toughness, the welding process can influence corrosion performance. The welding process in order of increasing corrosion resistance in this solution are: GTAW; GMAW; FCAW and SAW; SMAW-basic coating; SMAW-rutile coating. The low ranking of the GTAW process is explained by a loss of nitrogen from the weld pool. To counteract this effect, it is po
ssible to either add nitrogen to the torch gas or u an overalloyed filler metal, e.g., Avesta Welding Products P100 (25Cr-9.5Ni-3.6Mo-0.22N).
Joint Design
Some joint designs that can be ud for 2205 are shown in Joint Designs 1–8. The goal of the designs is full penetration with minimal risk of burn-through. Many other designs are possible. For example, when the material thickness exceeds 0.5 inch (12 mm) and it is possible to weld from both sides, the joint designs in Joint Designs 3–5 can be made symmetrical.
The root bead may be deposited using either GTAW (TIG) or SMAW (coated electrodes).
If GTAW is ud, an inert backing gas should be applied when tacking. The root side of a root bead deposited by SMAW should be cleaned after Square Butt Joint Joint Design 1
Type 2205 Code Plus Two ® Duplex Stainless Steel
4welding. A suitable electrode diameter is 5⁄64–3⁄32inch (2–2.4 mm), depending on ba metal thickness, welding position, and accessibility for root-side grinding.
Selection of a joint design should accommodate the following guidelines:
1. It should be easy to achieve full penetration
with a good margin of safety.
2. The welder should keep slag formation and the
weld pool under obrvation.
3. Adequate backing gas shielding should be
provided to avoid root defects harmful to corrosion resistance or mechanical properties.4. Excessive weaving and wide molten pools
should be avoided to prevent excessively high heat input and high stress.
5. Extremely low heat inputs with rapid quenching
should be avoided to prevent predominantly ferritic heat-affected zones.
Joint Preparation Cleaning
Cleaning of joints and adjacent surfaces before welding is good practice for all stainless steels.Dirt, oils, and paint can cau weld defects.
Common solvents such as acetone or mineral spirits can be ud as cleaning agents. Moisture in the joint can cau porosity or weld metal cracking.It is important that joint preparation follow the desired joint design accurately. Large variations in preparation can cau substantial variations in the land thickness or the gap distance, thereby affecting the consistency of the weld. Edge preparation
Square Butt Joint
Joint Design 2
Single V Joint
Joint Design 3
Single V Joint
Joint Design 5
Single U Joint
Joint Design 4
Type 2205 Code Plus Two® Duplex Stainless Steel5
Preheating and Post-Weld Array Heat Treatment
Preheating of 2205 is not normally necessary. It may
be helpful in cold ambient conditions to avoid the
risk of condensation and possible resultant porosity.
In such cas the 2205 may be heated carefully and
uniformly to less than 200°F (95°C), and only after
the weld joint has been thoroughly cleaned.
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If the 2205 is greater than about 0.625 inch
(16 mm) thickness, and welding is to be done with
very low heat input (≤12 kJ/inch, 0.5 kJ/mm),
preheating to the range of 200–300°F (95–150°C)
can be uful. The purpo of this preheating is to
avoid excessively rapid cooling and a resulting
extremely high ferrite content. A similar upper
temperature limit applies to interpass temperatures.
Postweld heat treatment is not normally
论文网站大全necessary. If it becomes necessary for any reason,
it should be done at 1900°F (1040°C) minimum,
followed by rapid cooling. Exposure in the range
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1200–1830°F (650–1000°C) is very harmful to
toughness and corrosion resistance becau of
formation of carbides, or sigma or other
intermetallic phas.
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Interpass Temperature
The maximum interpass temperature for 2205 is
300ºF (150ºC).
Distortion
Controlling distortion of 2205 is not significantly
different from controlling distortion of austenitic
stainless steels. Good practice includes proper
fixturing, cross supports, braces, staggered bead
placement, and weld quence, etc. The edges of
the plate or sheet should be squared, aligned, and
tacked prior to welding. The coefficient of thermal
expansion of 2205 is intermediate to tho for
carbon steel and for austenitic stainless steels such
as Type 304L.
Workmanship, Inspection, and
Quality Assurance
2205 should be welded in accordance with
predetermined fabrication and inspection plans
by skilled and trained operators.
