Carpenter20, Duplex and Super Duplex Materials

Please search the wep for your questions

(Duplex+SS+Chemical) gives the site - 4th in a 445,000 results

http://www.azom.com/details.asp?ArticleID=2870

It has the chemical, mechanical properties and application

same exercise with Super Duplex gives

www.alliancevalves.co.uk/super-duplex/super-duplex-uns-S32750.htm

(10th out of 10,700)

do you want us to do the google search for you ?

Pl come with specific question and not general and you will be appreciated -

I want a flange for HCl what you think is best - Carpenter20, Duplex or Super Duplex or any other

(sorry can not give GA as per my promise to myself )

The quality of problems in CR4 is going down - almost one in three are where the google/wiki is enough.

I liked the question next (the hyd motor , but alas no experience or the vibrating motor - insufficient information but they had at least genuine questions)

Some times I feel I should make a resolution to only answer off topic except on genuine questions - since these questions are anyway off topic by themselves.

Rather than condescend why not offer up some information.

Duplex stainless steels are so called because the alloy structure contains both austenitic and ferritic phases. The result is a stainless steel that combines excellent corrosion resistance, high strength and toughness. A typical duplex would have ~22% Cr, 5 Ni and 3 Mo.

Super Duplex adds additional Cr and Ni (~25% and 8%) for added corrosion resistance and strength.

Hastelloy is a nickel-based super alloy family trademarked by Haynes International. Although all of the alloys mentioned are expensive, in general, the cost of hastelloy can only be justified where the iron-based alloys won't perform.

As previously mentioned Carpenter 20 is a specific alloy. It is a 20%Cr austenitic stainless typically used in hot chloride environments.

Good luck.

I don't know about hot chloride resistance, but Carpenter20 or Alloy20 as it is sometimes called is widely used in the US water treatment industry for handling sulfuric acid used in regeneration service of cation ion exchanger resin. It often appears in project specifications written by many of the US architect/engineering companies.

1."Hastelloy" decribes a family of corrosion-resistant alloys, while "Carpenter 20" is the name of a specific alloy made by Cartech.

2 For additional information on tthese classes of alloys, see the Cartech web-site. You'll have to register, but once you do. you can scroll through their site and get answers to your questions.

Hi Govin,

Stainless steels are also classified by their crystalline structure:

• Austenitic, or 300 series, stainless steels comprise over 70% of total stainless steel production. They contain a maximum of 0.15% carbon, a minimum of 16% chromium and sufficient nickel and/or manganese to retain an austenitic structure at all temperatures from the cryogenic region to the melting point of the alloy. A typical composition of 18% chromium and 10% nickel, commonly known as 18/10 stainless, is often used in flatware. Similarly, 18/0 and 18/8 are also available. Superaustenitic stainless steels, such as alloy AL-6XN and 254SMO, exhibit great resistance to chloride pitting and crevice corrosion due to high molybdenum content (>6%) and nitrogen additions, and the higher nickel content ensures better resistance to stress-corrosion cracking versus the 300 series. The higher alloy content of superaustenitic steels makes them more expensive. Other steels can offer similar performance at lower cost and are preferred in certain applications.^{[citation needed]}

The low carbon version of the Austenitic Stainless Steel, for example 316L or 304L, are used to avoid corrosion problem caused by welding. The "L" means that the carbon content of the Stainless Steel is below 0.03%, this will reduce the sensitization effect, precipitation of Chromium Carbides, due to the high temperature produced by welding operation.

• Ferritic stainless steels are highly corrosion-resistant, but less durable than austenitic grades. They contain between 10.5% and 27% chromium and very little nickel, if any, but some types can contain lead. Most compositions include molybdenum; some, aluminium or titanium. Common ferritic grades include 18Cr-2Mo, 26Cr-1Mo, 29Cr-4Mo, and 29Cr-4Mo-2Ni.

• Martensitic stainless steels are not as corrosion-resistant as the other two classes but are extremely strong and tough, as well as highly machineable, and can be hardened by heat treatment. Martensitic stainless steel contains chromium (12-14%), molybdenum (0.2-1%), nickel (0-<2%), and carbon (about 0.1-1%) (giving it more hardness but making the material a bit more brittle). It is quenched and magnetic.

• Precipitation-hardening martensitic stainless steels have corrosion resistance comparable to austenitic varieties, but can be precipitation hardened to even higher strengths than the other martensitic grades. The most common, 17-4PH, uses about 17% chromium and 4% nickel. There is a rising trend in defense budgets to opt for an ultra-high-strength stainless steel when possible in new projects, as it is estimated that 2% of the US GDP is spent dealing with corrosion. The Lockheed-Martin Joint Strike Fighter is the first aircraft to use a precipitation-hardenable stainless steel—Carpenter Custom 465—in its airframe.

• Duplex stainless steels have a mixed microstructure of austenite and ferrite, the aim being to produce a 50/50 mix, although in commercial alloys, the mix may be 40/60 respectively. Duplex steels have improved strength over austenitic stainless steels and also improved resistance to localised corrosion, particularly pitting, crevice corrosion and stress corrosion cracking. They are characterised by high chromium (19–28%) and molybdenum (up to 5%) and lower nickel contents than austenitic stainless steels. The most used Duplex Stainless Steel are the 2205 (22% Chromium, 5% Nickel) and 2507 (25% Chromium, 7% Nickel) sometimes the 2507 is also called "SuperDuplex" due to the higher Corrosion resistance.

Alloy 20 is a corrosion-resistant nickel-chromium-molybdenum stainless steel alloy developed for applications involving sulfuric acid. Its corrosion resistance also finds other uses in the chemical, food, pharmaceutical, and plastics industries. Alloy 20 resists pitting and chloride ion corrosion and its copper content protects it from sulfuric acid.

It is also known as Carpenter 20. Cast versions are designated CN7M.

This is article from Wikipedia...

http://en.wikipedia.org/wiki/Stainless_steel

Very Nice Information..Thanks for sharing..

Rajendra Piyush Skytech Csteel Asiad Maruti Stolt GTPL Metaltube