new duplex grades 5

[mcguire]

There are several lean duplex grades which have some attractive features. 2003, for instance, has the pitting resistance of 317L, high strength, and resistance to SCC.
Their releatively low alloy content makes them less expensive than their equivalent austenitic alloys, in this case 317L.

My question is to users of 316 and 317. Have you considered switching to such a grade? If so, has it worked out well?
If not, what has been the problem? If you haven't considered changing, why not?

Michael McGuire

http://stainlesssteelforengineers.blogspot.com/

 

[EdStainless]

I have been less than sucessful in getting prople to change. No one wants any risk. They have all fired the engineers that did the design work, and they don't understand their own equipment well enough to make such decisions any more.
I am working with a few people right now, but it is slow. I am looking applications where they are using cold finished 316 for strength. With AL2003 you can either use it annealed and have the same strength or use it cold finished at much higher strengths and save some weight.

There is some success with LDX2101, but almost all of that has been in plate. You can save money if you are building a large tank and you switch from 304 to 2101.

19D has been used in may small diameter applications, but its corrosion resistance is so poor that in many cases it is Zn coated in order to protect it.

The old workhorse, 2304, is also a plate grade. It works very well in caustic service so the paper guys like it. It is hard to find in other product forms.

(now I step off of soap box)

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[gciriani]

Hi Mike! How do the new duplex grades compare relative to 316L in the following categories (all relevant to my industry, SS luxury goods):
(1) Machining ease (speed of utensil advancement);
(2) Malleability (it correlates well with mirror polishing ability);
(3) Nickel content;
(4) Nickel release (it correlates negatively with allergy potential to the wearer);
(5) Cost;
(6) Hardness after cold work.

 

[mcguire]

Hi Giovani
Let me first send you to the website of Allegheny for their data on 2003.

http://www.alleghenyludlum.com/ludlum/Documents/AL_2003.pdf

These alloys do have lower nickel which is highly alloyed to prevent nickel release. Their machinability should be better than 316L.
I can't guess how well they will polish with their dual phase structure. Ask Allegheny via their site.

Michael McGuire

http://stainlesssteelforengineers.blogspot.com/

 

[EdStainless]

I'll take a crack at this.
Giovani, These alloys are stonger than 3XX alloys. Unless you can take advantage of that in your application they probably don't make sense. They cost about the same as 316 on a per pound basis, even condisering the huge surcharges these days.
The alloys machine well. They take more power to bend, punch or cut, but they are not sticky like 316. They don't machine like steel, but they don't weld to your tooling either.
The hardnesses are nice. We have cold drawn 2003 tubing and had no trouble reaching 140ksi yield, 160ksi UTS. We stil had elongations over 15% and hardness was Rc 36-38.
The lean duplex grades have good chloride cracking resistance. I see a lot of potential for these alloys in hot water applications.

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[gciriani]

Happy 4th of July!

Mike and Ed, thanks for the explanations, and the Allegheny website. I guess I completely overlooked the fact that ferromagnetism is also a no-no (watch components and accessories like the watchbands we produce) have to be non-ferromagnetic. Therefore duplex SS cannot be used in my applications.

I also looked up a stress-strain curve (page 23 figure 21,

http://www.outokumpu.com/files/Group/HR/Documents/STAINLESS20.pdf)

comparing 2205 to 316, which shows the 316 curve to bend much earlier: this should be an indicator of malleability (please correct me if I'm wrong), which is important to attain mirror-polish ability. It is also important for my products to be free of ferrite-delta, since this also affect polishing (when performing buffing, impurities show up as comets, i.e. a minuscule dot with a streak tail).

By the way since you are the experts, can you tell me what curves refer to what axes in figure 24 page 27 of the same document referenced above? (there are continuous, broken, and broken-dotted lines referring to either stress, or elongation axis, but it isn't clear what curve is Rp0.2, Rm and A5).

Giovanni Ciriani
Promotion Group +39-348-155-4029

 

[mcguire]

That's a tough read in figure 24. The downward sloping lines are the eleongation. The dotted lines which increase are yield strength and the solid lines are tensile strength.

I am not aware of the correlation between mirror polishing ability and malleability, so I don't know which specific trait on a stress-strain curve is most important. Malleability is more a colloquial word than an engineering term. I don't know if it relates to total elongation or low work hardening rate or what. Anyone else know?

Michael McGuire

http://stainlesssteelforengineers.blogspot.com/

 

[gciriani]

I agree that malleability is a colloquial term, and that there isn't a measurable number associated with it. Actually I should have said ductility: from a linguistic point of view I'm always confused between malleability and ductility.

Quoting the web page of my previous message, at page 25, 4th line from the bottom:
"Austenitic steels exhibit very high ductility: they have a high elongation and are very tough."

From buffing practitioners I hear that the mirror-polish appearance is obtained by using a wheel that goes at about 1000 m/min (38 mph), which heats and bends the top layer, mobilizing it over the micro irregularities of the surface, and creating therefore a very smooth appearance. Please forgive me for aving highjacked this thread in a different direction.

Giovanni Ciriani
Promotion Group +39-348-155-4029

 

[EdStainless]

In buffing you rely on smearing the outer surface of hte metal. In most applications we try to avoid this since it hurts corrosion resistance.
It would be difficult to smear the duplex since it is strong and you will get additional work hardening.
We mechanically polish to about 10 microinches and then electropolish. You can tell that the lusture is less than in 316, though it takes a high magification to see the duplex structure.
Yes, they are very ferromagnetic. I keep forgetting to mention that up front.

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[unclesyd]

gciriani,
Malleability isn't a bad word to use, especially in your line of work as part of the jewelry business. I'm looking at handbook that says that Gold is the most malleable of all metals, so much so that it can be hammered thin enough to see through. It goes on to list the malleability of different precious metals

The word malleable is used by blacksmiths and the hand forging practitioners. This bunch will tell you right quick that SS isn't at all malleable compared to other metals.

And we always have Malleable Iron and a simple test used to check it as it came out of the furnace was to put a piece under a small trip hammer and see if you could "smush (flatten) it" without it cracking. The furnace was called a Malleablizing (Annealing) furnace.

I think that the term is used more if the material is to hammered, in very broad sense, coined, or embossed and so on. I also have malleability used when discussing high energy rate forming.

EdStainless,
If you were relying on mechanical polishing couldn't you possibly see differential polishing using a duplex. We used an entirely different polishing process between the different stainless steels. The technique for 316 SS vs the one for 420 SS were worlds apart as was the process for 430 SS.

 

[gciriani]

Unclesyd,
I would be very interested in reading the malleability chapter of the handbook you mention. Could you give me the title, author and editor please? (Ciriani@Promotion-Spa.Com) I would also like to find out which austenitic SS is more malleable (I believe it is 316, but you never know).

Giovanni Ciriani
Promotion Group +39-348-155-4029

 

[EdStainless]

Yes, we see a difference between the two phases when we EP. We are using EP to generate a featurless surface. The macro smoothness is secondary.
The mallebility of SS is limited by its strain hardening characteristics. The ferritics work harden less, the high alloy austenitics more.
Cu and Au, (as well as Zn, Ag and a few others) undergo strain recovery at room temp when they are highly worked. In otherwords you don't need to use intermediate anneals for heavy reductions.

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[StoneCold]

mcguire
I have gotten some pricing for 2205 pipe and it is still about twice 316L ERW. (I prefer the seamless but could not get a quote for 2205 seamless). When I saw the higher cost for the pipe I did not look for fittings. Almost all the corrosion resistant applications we have involve piping or tanks. I have not gotten quotes on any 2205 tanks yet but I plan to in the future. I admit my exposure to the duplex stainless is very low so the only one I know anything about is the 2205. We use a ton of 316L pipe and fittings. I would like to switch to either an equivalent or higher grade of duplex for a similar cost but I don't know which one.
I have looked around a little bit for 317L and SMO 254 but most people give you a blank stare when you bring up the subject of more exotic stainless alloys.
Where is a good online source for duplex stainless?

Thanks
StoneCold

 

[mcguire]

StoneCold
2205 has a lot of moly which offsets its lower nickel. Allegheny makes a low moly grade, 2003, which is equivalent to 317L in corrosion resistance and stronger, so it should afford a savings if you can reduce wall thickness.
Same for 2101 from Outukumpu. Both have sites which accept
inquiries. Tell them I sent you.
These grades are priced too high, mainly because stainless producers aren't enlightened marketers. In the end if the alloy savings are real, and they are, then pricing will fall into line.

Michael McGuire

http://stainlesssteelforengineers.blogspot.com/

 

[EdStainless]

StoneCold,
Are you using pipe? like 2"80s in 316L and 2"10s in 2205. You aren't using the same gage are you? There is no sense in that. That is one of the biggest reasons to use duplex.

There is also no point in using seamless tubular, unless for your size it costs less. Sepcify the product correctly, require the right NDT, audit suppliers, and use the product. Poorly made seamless pipe will cause just as many problems as poorly made welded.
Or if you really care you can use tubing. The specs are tighter.

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[StoneCold]

Edstainless
We usually run sch 40s in 316L and we have dropped all our C276 applications to sch 10S. However since almost all of what we do in stainless is 4" or less, if we specify sch 10 fitting a lot of what we get are tapered end sch 40 fittings and there is no cost savings. The availability of true sch 10 fittings even in 316L seems to be poor.

I will try to get some 2205 sch 10 pipe and fitting quotes as well as look at the 2003 and the 2101 grades.

Most of our aplications are low pressure and vacuum, multiuse services that over time chew pin holes in the stainless. Mostly in the welds or heat affected zones.

Thanks for your help and insite into metals.

StoneCold

 

[mcguire]

Sounds like a market opportunity for a clever tubing company, Ed.

Michael McGuire

http://stainlesssteelforengineers.blogspot.com/

 

[EdStainless]

If you are having weld related pinholes I presume that they are in both the pipe seamwelds and in your field welds.
You can require that the pipe be annealed (real anneal)by either setting a maximim level of magnetism, or by requiring an A249 S7 weld decay test.
This can take care of the seamweld, but your field welding methods will need to be tightly controled to help those.

We have a numbe rof customers that we make tubing for, that looks (dimensionally) like 5s pipe, but we make it as tubing.

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[rolledalloy]

My company is stocking the LDX 2101 variety of lean duplex. This alloy with 1.5% Ni and 0.3% Mo nominally is not impacted as dramatically by the high surcharges on Nickel and Molybdenum. As a result this duplex unlike 2205 is lower in cost than 316L in flat products and round bar by about 15% currently. We have plate, sheet and weld products in inventory and we have round bar and SCH 10 pipe on order for those interested.

Machinability on LDX 2101 is much better than with traditional duplexes like 2205 according to the data supplied by Outokumpu. Its machinability is reported to be better than 316L. This may be a result of its higher manganese content (Manganese is substituted for Nickel as an austenitizer).

Jason Wilson

http://www.rolledalloys.com

 

[mcguire]

rolledalloy
I'm trying to make a price comparison of a number of grades for the new stainless book. Can you give a current ratio of the prices of 2101, 2003, 2205, 2507 and AL6XN to that of 304? I realize that surcharges skew this, but that's reality.

Michael McGuire

http://stainlesssteelforengineers.blogspot.com/