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AGA CW Handbook A4_32130-UK
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28 shielding gases for
stainless
steels
contents 7.1 general 7.2 which shielding gases are suited to different steel grades 7.2.1 mig/mag welding 7.2.2 tig welding 7.2.3 root protection selection table 7.1 general
stainless
steels
are high-alloy
steels
which can be divided into different types based on their microstructures. the most common steel types are listed in the table below. ferritic and martensitic
stainless
steels
have strength properties which are similar to unalloyed and low-alloy
steels
. they are excellently suited to use as structural steel and have a high heat resistance. however, these
steels
are not as corrosion-resistant as austenitic stain- less
steels
,which are used most out of all
stainless
steels
. their typical properties include good corrosion resistance and good impact ductility even at low temperatures. high-alloy austenitic
stainless
steels
contain more chromium, nickel, molybdenum and nitrogen, which makes them more corrosion resistant than regular austenitic grades. unlike regular austenitic
stainless
steels
, the ferrite content of the weld is around 5% after welding, the weld is fully austenitic after welding with high-alloy austenitic grades.
steels
type application examples ferritic chemical
industry
, household for example appliances, boilers, exhaust aisi 430 ti, x 3 crti 17, w.nr 1.4510 pipes. x 2 crmoti 18 2, w.nr 1.4521, ss 2326 martensitic mechanical engineering, for example water turbines, steam pipe- aisi 410, x 12 cr 13, w.nr 1.4006, ss 2302 lines, ship propellers. austenitic oil and gas
industry
, chemi for example cal
industry
, paper and pulp aisi 304, x 5 crni 18 10, w.nr 1.4301,
industry
, food
industry
, house - ss 2333 aisi 316, x 3 crnimo 17 13 3, hold items, mechanical engi- w.nr 1.4436, ss 2343 neering, vehicles, medical instruments. high-alloy austenitic oil and gas
industry
, chemical for example
industry
, paper and pulp aisi 317 l, x 2 crnimo 18 15 4,
industry
, flue gas washers. w.nr 1.4438, ss 2367 duplex (ferritic-austenitic) oil and gas
industry
, chemical for example
industry
, seawater technology. aisi 329, x 3 crnimon 27 5 2, w.nr 1.4460, ss 2324 superduplex oil and gas
industry
, chemical for example
industry
, paper and pulp x 2 crnimocun 25 6 3, w.nr 1.4507
industry
, seawater technology. ferritic-austenitic
stainless
steels
are known as duplex
steels
. their benefits include high yield strength and good resistance to stress corrosion, as well as good resistance to general corrosion and spot corrosion.superduplex
steels
were developed from duplex
steels
. in superduplex grades, the corrosion resistance of the steel has been further improved by adding alloy materials such as nitrogen. shielding gases for
stainless
steels
.
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